Acknowledgements

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Food and Nutrition Bulletin, vol. 11, no. 3

(c) The United Nations University, 1989

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Introduction: Vitamin-A deficiency and child health and survival

Reynaldo Martorell

From the early days of its discovery, vitamin A has been popularly known as the anti-infection vitamin [1]. This was due to the evidence that quickly accumulated from animal models which showed that vitamin A deficiency led to impaired immunocompetence and to increased susceptibility to and duration and severity of infections. Documentation of these effects in humans lagged far behind; in fact, it is only recently that well-conducted studies have been initiated.

The Committee on International Nutrition Programs (CINP) was formed in 1970 to provide guidance to the Office of Nutrition of the US Agency for International Development (USAID) on scientific questions relevant to international nutrition programmes. The ClNP's interest in vitamin-A deficiency and child health and survival has had a long history. For example, in 1976 the CINP issued a report entitled Possible Health Benefits of Vitamin A Prophylaxis Programs in Addition to the Prevention of Xerophthalmia and Blindness [1]. The report reviewed the literature and concluded that it was not known whether providing vitamin A to deficient human populations would result in health benefits other than those associated with the eyes. In a report that same year entitled Priorities for Research on Avitaminosis A and Xerophthalmia, the CINP identified, as one of four priority areas, the need for epidemiological studies of avitaminosis A and its relation to infection [2]. The committee went on to offer specific suggestions for studies of vitamin A and immunity and for assessing the impact of vitamin-A control programmes on infection.

A number of important studies carried out subsequent to the publication of these two reports supported a link between vitamin A and child survival.

Studies in Indonesia suggested an association between vitamin-A deficiency and mortality in children with signs no more severe than the World Health Organizations categories of XNC (night blindness) and XIB (Bitot's spots) [3]. In a subsequent community trial, children living in Indonesian villages without a programme of vitamin-A supplementation were found to have a mortality rate 35% greater than those in a control village with a programme 14]. Few studies have created as much interest and debate in the international health and nutrition community as this one. Questions have been raised regarding the validity of the findings because of issues involving design and measurement [5].

The possibility that child mortality in developing countries can be so dramatically reduced by means of a simple and cheap intervention is encouraging if it can be confirmed. There is a marked contrast between the relative ease and low cost of implementing an effective programme of vitamin-A supplementation (i.e. providing two doses of 200,000 IU orally to children a year) and the requirements for other approaches to improving health and survival, such as water and sanitation programmes or the eradication of protein-energy deficiency, which even at their best do not usually show the type of immediate and dramatic effects on mortality that were observed in Indonesia. Given the potential policy implications of the Indonesian findings, the CINP felt it was important to determine whether the mortality effects observed could be replicated in other settings using the best possible epidemiological methods.

The late director of the Office of Nutrition of USAID, Dr. Martin Forman, also saw the need for further research, and at his request the CINP established a Subcommittee on Vitamin A Deficiency Prevention and Control. In August 1986 the subcommittee conducted a workshop that culminated in the report Methodologies for Field Trials of Vitamin A Supplementation [5], which dealt primarily with methods for assessing the impact of vitamin-A supplementation on child mortality in order to provide scientific and technical guidance for the design of the several field trials planned by USAID to verify that impact in developing countries.

Subsequently, the Office of Nutrition requested that the subcommittee explicitly consider the mechanisms that might explain the hypothesized effects of vitamin A on mortality. To this end, a workshop was held on 28 April 1988. The five papers that follow are a result of this workshop.

The first represents the subcommittee's technical recommendations for conducting studies of the mechanisms through which vitamin A might affect mortality, and refers primarily, but not exclusively, to studies of vitamin A and infection. The subcommittee's recommendations took into account the papers presented at the workshop, the general discussion which these generated, and subsequent deliberations by its members. The other four papers were presented at the workshop.

Drs. Chandra and Vyas's review of animal and human research on vitamin A and immunocompetence and De Luca and McDowell's review of the effects of vitamin-A status on hamster tracheal epithelium in viva and in vitro indicate that vitamin A plays a number of physiological functions that contribute to host defence. These two papers offer reasonable mechanisms that would explain a relationship between vitamin-A deficiency and increased incidence and severity of infection.

The studies of vitamin-A deficiency and risk of respiratory and gastrointestinal infections are critically reviewed by Dr. Forman, who points out that, despite some strong epidemiological support for an association between vitamin-A deficiency and infection, the issue remains clouded by design and measurement problems. In the fifth paper, Dr. Porter reviews ethical issues relating to nutrition field trials. Ethics is always a consideration in research involving humans, and in the case of studies of vitamin A and child health and survival, ethical discussions have loomed large. For example, the Subcommittee on Vitamin A Deficiency Prevention and Control could not come to a consensus regarding the designs to be recommended for trials of vitamin-A supplementation and mortality, and two of its members wrote minority reports questioning the majority's endorsement of controlled trials, a type of study where a control population does not receive vitamin-A supplementation. The majority felt rigorous scientific designs were preferred in order to quickly establish whether or not vitamin-A supplementation to deficient populations has a significant impact on child health and survival as suggested by the Indonesian findings. Some of the recent vitamin-A studies funded by USAID have also generated heated discussions of ethical issues and have had to be modified as a result.

Vitamin-A deficiency is widespread but unevenly distributed among developing countries. For those countries in which vitamin-A deficiency is a public health problem, there are effective programmes that can be implemented, including supplementation, fortification, horticulture, and nutrition education. These must compete for funding with programmes for ameliorating or eradicating other health and nutrition problems. Governments must make difficult choices in selecting the mix of programmes to be implemented; clearly, impact on child health and survival ought to be a salient consideration. Thus it is important for us to know with certainty what effects vitamin-A improvements would have and under what conditions. These answers are best obtained through adequately designed and carefully conducted clinical and epidemiological studies. It is hoped that the work of the Subcommittee on Vitamin A Deficiency and Control and the contributions of the scientists whose papers are included here point in the right directions.

References

1. National Research Council. Possible health benefits of vitamin A prophylaxis programs in addition to the prevention of xerophthalmia and blindness. Report of the Committee on International Programs, Food and Nutrition Board. Washington, D.C.: National Academy of Sciences, 1976.
2. National Research Council. Priorities for research on avitaminosis A and xerophthalmia. Report of the Committee on Intemational Programs, Food and Nutrition Board. Washington, D.C.: National Academy of Sciences, 1976.
3. Sommer A, Tarwotjo I, Hussaini G. Susanto D. Increased mortality in children with mild vitamin A deficiency. Lancet 1983;2:585-88.
4. Sommer A, Tarwatjo I, Djunacdi E, et al. Impact of vitamin A supplementation on childhood mortality: a randomized controlled community trial. Lancet 1986; 1:1169-73.
5. National Research Council, Subcommittee on Vitamin A Deficiency. Vitamin A supplementation: methodologies for field trials. Washington, D.C.: National Academy Press, 1987.

Research priorities for investigation of the influence of vitamin-A supplementation on morbidity

A statement

by the Subcommittee on Vitamin A Deficiency Prevention and Control

The Subcommittee on Vitamin A Deficiency Prevention and Control of the Food and Nutrition Board's Committee on International Programs conducted workshop on Strategies and Priorities for Research on the Influence of Vitamin A Supplementation on Morbidity on 28 April 1988. The purpose of the workshop was to consider the influences of vitamin A on the immune system, the role of vitamin A in the differentiation and maintenance of epithelial tissue, the current research and recent findings on vitamin A and morbidity, and the ethical dimensions of such research.

This report was written by the subcommittee subsequent to the workshop and represents the consensus of its members. It does not give equal weight to all hypotheses considered at the workshop but emphasizes those relating vitamin A to infections within the context of field studies. In addition, the report includes a detailed discussion of methods of assessment of vitamin-A status. It does not discuss the ethical issues in any great detail because these were discussed very thoroughly in its previous report and in Dr. Porter's paper below (pp. 36-40).

The following hypotheses were addressed at the workshop:

• Marginal vitamin-A deficiency adversely affects the integrity of epithelial tissue.
• Marginal vitamin-A deficiency lowers resistance to infection by affecting the immune system.
• Marginal vitamin-A deficiency is a risk factor for the increased incidence and severity of diarrhoeal and respiratory infections.
• Vitamin-A supplementation to populations in which vitamin-A status is marginal increases immunocompetence and reduces the incidence and severity of diarrhoeal and respiratory infections.

The word marginal is used to describe the range of vitamin-A deficiency of interest to the subcommittee; it refers to the subclinical stage preceding the appearance of night blindness and the conjunctival and corneal changes characteristic of xerophthalmia. Although it is difficult to define marginal vitamin-A deficiency adequately, it is nonetheless clear that in countries where xerophthalmia is a significant public health problem a large proportion of children are afflicted with marginal deficiency. The World Health Organization considers prevalences of corneal xerosis and keratomalacia (X2 + X3A + X3B)* in excess of 0.01% to indicate a significant public health problem affecting large numbers of children [1]. In such areas, many more children will show less severe clinical signs (X1A, X1B) and night blindness (my), and even more will have low plasma vitamin A, low vitamin-A stores in the liver, and vitamin-A-deficient diets. Xerophthalmia is known to be associated with diminished host defences and increased risk of infection. Similarly, marginal vitamin-A deficiency may lower resistance to infection, a possibility that needs to be confirmed and quantified through adequately designed studies. Because so many children are likely to be affected by marginal vitamin-A deficiency, the study of this condition and its implications constitutes a significant research priority.

The subcommittee's first report considered effects of vitamin A on mortality and provided advice on the conduct of field studies designed to test the hypothesis that vitamin-A supplementation lowers child mortality rates [2]. Mortality studies require very large samples in order to achieve satisfactory statistical power.

The study of morbidity related to vitamin A is more feasible since infections occur more frequently and fewer subjects need be studied. Mortality and morbidity studies are complementary. The demonstration of an effect of vitamin-A supplementation on the incidence and severity of gastrointestinal and respiratory infections would strengthen the persuasiveness of findings on mortality because such a demonstration would provide a plausible pathway leading to the mortality effects. Similarly, the demonstration of effects of marginal vitamin-A deficiency on epithelialtissue differentiation and maintenance and on immunocompetence would further validate both morbidity and mortality findings.

Research gaps

The subcommittee has assessed progress to date in regard to morbidity effects and has determined that further research is required. Salient research gaps are as follows.

Immuncompetence

Vitamin-A deficiency both in man and in laboratory animals impairs immunological responses [3]. Although not all of the immune responses have been tested in man, the consensus of results in published studies indicates that the following parameters are altered. Reduced vitamin-A intake and low serum-rehnol concentrations are associated with decreased delayed hypersensitivity response, lower serum-antibody response to some antigens, decreased lymphocyte response to mitogens, decreased natural-killer-cell activity, delayed rejection of grafts, changes in complement level, and phagocyte dysfunction. Several published reviews are available [4-6]. In animals deficient in vitamin A, morbidity and mortality increased after infectious challenge 13]. The significance of these findings in humans remains to be established.

In general, changes in immunocompetence often precede obvious infection and can be viewed as a functional index of nutritional deficiency. Changes in immune responses may mediate heightened susceptibility to infection in populations deficient in vitamin A.

More information should be obtained through research in the following areas:

• epithelial-tissue integrity and barrier function in vitamin-A-deficient individuals, particularly in marginal stages of deficiency, including examination of the effect of vitamin-A supplementation;
• the pattern of recovery of immunocompetence following either small, frequent physiological amounts of vitamin A or massive pharmacological doses of vitamin A;
• secretory immunoglobulin and cell-mediated immune responses to immunization and the extent of protective immunity achieved in vitamin-A-deficient groups;
• investigation of the mechanism(s) by which vitamin-A deficiency alters immunocompetence;
• examination of the quantitative and temporal relationship between vitamin-A status and different indices of immune function.

Morbidity

The literature suggests that marginal vitamin-A deficiency is associated with increased incidence or severity of infections (or both). The evidence seems to be much stronger for respiratory than for gastrointestinal infections. The interpretation of the results to date is difficult because studies have failed to fully document vitamin-A status or to control for factors associated with both vitamin-A deficiency and the risk of infection.

An example is the need to control for environmental sanitation. Vitamin-A-deficient children may be from lower-income families with poorer housing and sanitary facilities. Children with adequate vitamin-A status, even when living in the same communities, may be from better-off homes. Thus, failure to control for environmental sanitation would overestimate the importance of vitamin A for morbidity. Similarly, vitamin-A deficiency generally coexists with other nutritional problems that are thought to affect the risk of morbidity. Studies of marginal vitamin-A deficiency and morbidity must at least control for protein-energy malnutrition and other deficiencies such as of zinc and iron.

Further research is recommended in the following areas:

• Identification of the extent to which the incidence and severity of infections are affected by marginal vitamin-A deficiency.
• The relation of marginal vitamin-A deficiency to specific types of morbidity: What types of morbidity are most affected by vitamin-A deficiency? What is the natural outcome of commonly occurring infections in the community and the role of immunocompetence in mediating the outcome? Are there different effects of vitamin-A supplementation or depletion on different infections - for example, on measles, rotavirus, and bacterial or viral pneumonias?
• Interaction of vitamin-A status with other deficiencies (for example, protein-energy, zinc, and iron) in regard to effects on morbidity.
• Interaction of vitamin-A status with factors related to socio-economic status, such as level of exposure to infection and access to health services.
• Effectiveness of massive doses of vitamin A versus lower doses given daily or weekly, adverse effects of massive doses, and mechanisms responsible for these different effects.

Indicators of vitamin-A status

In its first report [2], the subcommittee noted the importance of adequately characterizing the vitamin-A status of study populations. Such data will allow for stratification by vitamin-A status if required in the data analysis and will increase flexibility in extrapolating the results to other populations. The report also noted the problems in the measurement of vitamin-A status that require further methodological work:

• Biochemical indicators: How reliable and accurate are serum concentrations of vitamin A as indicators of overall vitamin-A status? How useful is the relative dose-response test?
• Cytological indicators: How useful is impression cytology as an index of vitamin-A status? Can buccal cytology be used instead of conjunctival cytology?
• Clinical history: How accurate are historical reports of night blindness?
• Dietary histories: How well do dietary histories for consumption of vitamin-A-rich foods actually correlate with vitamin-A intake and vitamin-A status?

Vitamin-A status is determined by total body stores and can be thought of in relative terms as deficient, depleted, adequate, excessive, or toxic. Deficient, excessive, and toxic concentrations are manifested by clinical signs and symptoms or by biochemical measures interpretable both for individuals and populations. Quantitative measurement of intermediate levels of vitamin A (depleted and adequate) is problematic and in need of research.

Vitamin-A status is also affected by absorption and other factors that increase metabolism, including infection and protein-energy malnutrition. Such factors should be considered in the design of studies to investigate the impact of vitamin A on morbidity.

Field-applicable indicators of marginal vitamin-A status currently recognized include serum concentrations, the relative dose-response test, and conjunctival-impression cytology. Each of these has limitations in feasibility and practicality in the field as well as in quantitative interpretation. Detailed discussions of methodologies for clinical histories and dietary histories are not specific to studies of vitamin A and morbidity and thus will not be discussed in detail here.

Serum concentrations

The interpretation of serum concentrations of vitamin A as reflectors of status on an individual and population basis have been discussed in a previous publication [2]. In the past, the interpretation of population distribution curves was largely based on comparisons with non-representative population surveys from developing countries from which cutoff points for deficient, low, and acceptable levels were derived [7]. Recently available are age- and sex-specific distribution curves for representative, relatively well nourished populations living in the United States [8; 9]. Although these reference curves appear to be independent of ethnic differences, they are influenced by environment [10; 11], and their usefulness as a universal reference needs to be validated. The most appropriate reference curve for serum levels for field studies of vitamin A and morbidity would be from a representative population known to have adequate body stores while living in an environment characteristic of an at-risk population. Studies are needed to establish appropriate reference curves for populations residing outside the United States and in high-risk areas. To obtain such references, distribution curves established before and repeated after large-dose supplements - for example, 30 days after a 200,000IU supplement - would be appropriate. These curves could then be compared with the US reference curves to determine whether there are differences.

Relative dose-response test

Whereas to demonstrate a rise in homeostatically controlled serum concentrations in response to increased intake or supplementation requires serially obtained samples with an intervening period for stabilization, the relative dose-response (RDR) test can detect depleted stores with only a five-hour interval between dosing and sampling [12; 13]. This test, modified to suit various conditions, has been successfully applied in both clinical and field-survey conditions. It has been validated by an intravenous procedure for dosing coupled with direct liver biopsy in a limited number of children with liver disease and adults [14;15]. The number of direct quantitative validation studies needs to be expanded to obtain greater assurance as to the range and confidence intervals of the association of a positive RDR test with vitamin-A concentrations in the liver. However, this can be accomplished only under specialized clinical circumstances, not in field studies in developing countries. Indirect validation with a before-and-after supplementation procedure also needs to be extended to population groups in which heavy intestinal parasitism, malabsorption, and protein-energy malnutrition are common. In addition, a proposed adaptation of the RDR method using didehydroretinol (DR, or vitamin A₂), a natural derivative of retinal (vitamin Al, the common form of vitamin A in foods and formed in the gut from carotenoids) [16], needs to be tested in human populations. If the DR adaptation proves reliable in human populations, only a single blood sample after five hours might be required, making the test much more feasible for field morbidity studies [17]. The RDR approach to assessment of depletion requires additional validity tests under field conditions to verify that mild to moderate protein-energy malnutrition, infections, or other conditions that may lower absolute serum concentration do not impede this short-term response and hence limit the applicability of the test for reliably indicating depletion of body stores.

Conjunctival-impression cytology

The histologically based conjunctival-impression cytology (CIC) test requires fewer logistical and technological resources than a direct biochemical determination of vitamin A. In theory, this increases its practicality for field studies in developing countries [18|. Validation against liver biopsies and the RDR test has been reported in a clinical setting among a very limited number of children with liver disease [19]. These studies suggest that the absence of goblet cells in the impressions corresponded to a liver concentration of <20 microg per gram, or a positive RDR, or both. Additional quantitative validation studies are needed but, as with the RDR, can be accomplished only under special clinical conditions. In a larger field study conducted in Guatemala, the CIC evaluated against the RDR was reported to lack sensitivity although it was specific [20; 21]. This field validation trial needs to be repeated. The effect of potential confounders such as concurrent eye infections, e.g. conjunctivitis and trachoma, should also be studied. The report of a strong linear correlation between abnormal CIC and relative plasma concentrations is not consistently reported by others under clinical or field conditions and needs confirmation [18]. Interpretation of the histological picture relative to degrees of vitamin-A depletion needs to be standardized.

Research needs in relation to vitamin-A assessment are as follows:

• Population reference curves of serum vitamin-A concentrations should be validated for developing countries.
• The relative dose-response test should be further validated under appropriate field conditions.
• Field trials to validate the conjunctival-impression cytology technique should be repeated.
• Standardization of the interpretation of histological findings for conjunctival-impression cytology relative to vitamin-A status is needed.

Indicators of nutritional status

The following issues related to indicators of nutritional status should be considered in designing studies of vitamin A and morbidity:

• What is the nature of the relation among nutritional status indicators and morbidity and immunocompetence? Is the relation linear, or are thresholds evident?
• While wasting is known to be related to increased risk of morbidity, the relation with stunting is less clear and should be explored further. In particular, studies should assess whether the process of stunting (linear growth retardation) is associated with diminished immunocompetence and increased morbidity.
• How should feeding histories be recorded, and which variables are most essential (i.e., duration of exclusive breast-feeding, type and timing of supplementary feeding, and duration of breastfeeding)?

Indicators of morbidity

• What are the validity and reliability of different methods of morbidity measurement?
• What is the definition of a "case" or episode?
• What are the diagnostic criteria for causal agents?

Measures of immunocompetence

The following measures of immunocompetence may be considered in the evaluation of vitamin-A-deficient individuals and populations before and after any proposed intervention. The rationale for choosing these four tests is based on the consistency of abnormalities observed in published studies and will be discussed further in the subcommittee's next report. The ultimate choice will be dictated by the nature of the study and practical considerations such as the availability of laboratory facilities and costs.

• delayed hypersensitivity,
• lymphocyte response to mitogens,
• salivary-immunoglobulin-A concentration,
• natural-killer-cell activity.

It would be important to role out the confounding effect of concurrent or recent infection on the basis of clinical findings and estimation of complement-reactive protein and endotoxins in the blood.

Strategies for research

The subcommittee recognizes that no single research design and set of procedures can or should be followed in a variety of settings in different countries with differing social contexts and resource limitations that affect feasibility. Nonetheless, the subcommittee wishes to present some guidelines that may prove useful in designing future studies.

Choice of population

It is desirable to test the major hypotheses in populations with various levels of vitamin-A nutriture.

Choice of deign

The subcommittee strongly recommends that double-blind randomized studies with placebo controls be used where feasible (as always, with due consideration for scientific and ethical issues). A controlled study is likely to yield information of greater scientific validity than a non-experimental study (e.g. a case-control study). Thus, experimental studies are preferable for unequivocally testing the hypotheses of interest.

In its previous report [2], the subcommittee reviewed theoretical and practical aspects of controlled trials. It noted, for example, that baseline comparability is ensured on average by random assignment of treatment and control interventions. The choice of the level of randomization - by individual, household, or community - is a matter of balancing considerations of study size with feasibility. If cluster sampling is used, appropriate statistical methods should be followed.

The likelihood of strict baseline comparability can be improved by randomization within strata on factors that relate to the outcome variables and that vary substantially among units to be randomized. Adequate stratification increases the precision of estimates, but must be weighed against the added field work that may result.

If strict comparability at baseline is not achieved in unstratified studies, adjustments are still possible during data analysis either by stratification or by regression analyses. This is possible, of course, only if the appropriate data have been collected at baseline.

The subcommittee recognizes the value of non-experimental studies and believes that they should be conducted where experiments are not feasible. Case-control studies, in particular, seem appropriate for studies of marginal vitamin-A status and risk of morbidity.

Case definition for such studies may present problems, however. If a case is defined as a child with diarrhoea at a given time and a control as a child without, the definition of a case will be weak as a result of the ephemeral nature of diarrhoea. Case definition could be improved by collecting histories of past infections; recall biases should be dealt with on the basis of the type of data. Another possible approach would be to select cases on the basis of marginal vitamin-A status, identify matched controls, and measure outcome through longitudinal follow-up. Such a design raises ethical issues related to the failure to treat those with identified clinical conditions. The subcommittee concurs with Feachem [22], who holds that such studies are unethical.

A major problem in case-control studies is the difficulty of satisfactorily matching for characteristics known to affect both the outcomes and vitamin-A status in the same direction. Case-control studies carried out to date have been equivocal because of poor matching. Variables to be matched should include age, sex, anthropometric and socio-economic status, nutritional status (anthropometric indicators of protein-energy malnutrition, indicators of iron and zinc deficiency, and other indicators where appropriate), environmental sanitation, and access to health care.

Content of the proposal

Below are listed issues which should be addressed in the design of proposals for future studies of vitamin-A supplementation and its relation to morbidity.

Specify the hypothesis

Research proposals should clearly state whether the hypothesis is to test the effect of marginal vitamin-A status on morbidity or to test the effect of vitamin-A supplementation on morbidity outcomes. If the hypothesis concerns testing the effect of marginal vitamin-A status, quantitative measures of depletion of vitamin A will be needed. The stated hypothesis should also indicate whether there is any intent to test the mechanisms by which vitamin-A deficiency or supplementation may lead to changes in morbidity - for example, by changes in immunocompetence. It should also state whether the intent is to study only morbidity per se or also severity of illness.

Specify sampling considerations and population description

• What type of population will be studied? What information is available that may be significant for vitamin-A studies?
• Is randomization to be done on the basis of the village or on an individual level?
• If randomization is on the level of village or cluster, how will cluster sampling affect estimates of sample size?

Specify expected effects

• What magnitude of effect on incidence or duration of morbidity is expected from vitamin-A supplementation? Is there any experimental basis for this estimate?
• How would different assumptions about the expected magnitude of the impact on morbidity affect sample size?

Specify methods

• Morbidity experience (for example, how will the frequency and duration of diarrhoea or respiratory disease be quantified?). Will attempts be made to identify causative agents?
• Data-collection plans.
• Indicators to be used for vitamin-A status (biochemical, clinical, dietary).
• Nutritional status (including feeding history, dietary history, and protein-energy, zinc, and iron nutritional status).
• Socio-economic status (for example, income, occupation, possessions, housing, education, exposure to infections, and access to services).
• Immunization status for immunizable diseases (especially measles).
• Intervening mechanisms such as immunocompetence.

Describe quality-control and data-management procedures

• What quality-control procedures will be implemented to ensure adequate coverage of the targeted population and satisfactory data quality?
• What data-management procedures will be used to ensure the availability of adequate information for analysis?

Specify the analysis plan

This should detail the specific methods to be used to test the study hypotheses and should, in addition, address the following issues:

• How will the analysis adjust for possible confounding factors such as nutritional status and socioeconomic status?
• What indicators will be used to quantify the key variables in the analysis (for example, vitamin-A status, nutritional status, socio-economic status, morbidity status)?
• Which indicators will be treated as dichotomous variables and which as continuous variables?
• If cluster sampling is used, how will adjustments be made for design effects when calculating confidence intervals?
• How will the analysis deal with multiple data points collected on the same individual? For example, if height and weight data are collected at several points, which measurements or combinations of measurements will be used to define nutritional status?
• What assumptions will be made in the statistical analysis, and what will be the effect of likely deviations from these assumptions?

This report is intended to provide guidance for developing programmes to assess the impact of vitamin A on child morbidity. It also gives an overview of the research priorities in this area, focusing on field studies of the impact of vitamin A on infectious diseases.

Subcommittee on Vitamin A Deficiency

Prevention and Control

Reynaldo Martorell (Chairman), Food Research Institute, Stanford University, Stanford, California

Abdelmonem A. Afifi, School of Public Health, University of California, Los Angeles, California

Guillermo Arroyave, School of Family and Consumer Sciences, San Diego State University, San Diego, California

Ranjit Kumar Chandra, Directory of Immunology, Memorial University of Newfoundland and Janeway Child Health Centre, St. John's, Newfoundland, Canada

Frank Chytil, Department of Biochemistry, School of Medicine, Vanderbilt University, Nashville, Tennessee

Samuel Preston, Population Studies Center, University of Pennsylvania, Philadelphia, Pennsylvania

Mervyn W. Susser, Columbia University, New York, New York

Frederick Trowbridge, Division of Nutrition, Center for Health Promotion and Education, Centers for Disease Control, Atlanta, Georgia

Barbara A. Underwood, National Eye Institute, National Institutes of Health, Bethesda, Maryland

Virginia H. Laukaran, Staff Officer, Food and Nutrition Board

Susan Berkow, Staff Officer, Food and Nutrition Board

Frances Peter, Deputy Director, Food and Nutrition Board

Jean Shirhall, Editor

References

1. World Health Organization. Control of vitamin A deficiency and xerophthalmia. Report of a joint WHO/ UNICEF/USAID/Helen Keller International/IVACG meeting. WHO technical report series, no. 672. Geneva: World Health Organization, 1982.
2. National Research Council-National Academy of Sciences, Food and Nutrition Board. Vitamin A supplementation: methodologies for field trials. Report of the Subcommittee on Vitamin A Deficiency Prevention and Control. Washington, D.C.: National Academy of Sciences, 1987.
3. Beisel WR. Single nutrients and immunity. Am J Clin Nutr 1982;35:417-68.
4. Chandra RK, ed. Nutrition and immunology. New York: Alan R. Liss, 1988.
5. Keusch G. Nutrition and infection. In: Remington JS, Schwartz MN, eds. Current clinical topics in infectious diseases. New York: McGraw-Hill, 1984:106-23
6. Vyas D, Chandra RK. Vitamin A and immunocompetence. In: Watson RR, ed. Nutrition, disease resistance and immune function. New York: Marcel Dekker, 1984:325-44.
7. Arroyave G. Chichester CO, Flores H. et al. Biochemical methodology for the assessment of vitamin A status. Washington, D.C: Vitamin A Consultative Group, Nutrition Foundation, 1982.
8. Pilch SM, ed. Assessment of vitamin A nutritional status of the US population based on data collected in the Health and Nutrition Examination Surveys. Prepared for the Center for Food Safety and Applied Nutrition. US Food and Drug Administration Contract No. FAD 233-84-2059. Bethesda, Md, USA: Life Sciences Reseach Office, Federation of American Societies for Experimental Biology, 1985.
9. Pilch SM, ed. Analysis of vitamin A data from the Health and Nutrition Examination Surveys. J Nutr 1987;117:636-40.
10. Looker AC, Johnson CL, Woteki CE, Yetley EA, Underwood BA. Ethnic and racial differences in serum vitamin A levels of children aged 4-11 years. Am J Clin Nutr 1988;47:247-52.
11. Looker AC, Johnson CL, Underwood BA. Serum retinal levels of persons ages 4-74 years from three Hispanic groups. Am J Clin Nutr 1988;48: 1490-96.
12. Flores H. Campos F. Araujo CRC, Underwood BA. Assessment of marginal vitamin A deficiency in Brazilian children using the relative dose-response procedure. Am J Clin Nutr 1984;40:1281-89.
13. Loerch ID, Underwood BA, Lewis KC. Response of plasma levels of vitamin A to a dose of vitamin A as an indicator of hepatic vitamin A reserves in rats. J Nutr 1979;109:778-86,
14. Amédée-Manesme O. Mourey MS, Hanck A, Therasse J. Vitamin A relative dose response test: validation by intravenous injection in children with liver disease. Am J Clin Nutr 1987;46:286-89.
15. Amédée-Manesme O. Anderson D, Olson JA. Relation of the relative dose response to liver concentrations of vitamin A in generally well-nourished surgical patients. Am J Clin Nutr 1984;39:898-902.
16. Tanumihardjo SA, Olson JA. A modified relative dose-response assay employing 3,4-didehydroretinol (vitamin A2) in rats. J Nutr 1988;118:598-603.
17. Olson IA. Indicators of vitamin A status. Bull Xerophthalmia Club 1988;38:3.
18. Natadisastra G. Wittpenn JR, West KP, Muhilal, Sommer A. Impression cytology for detection of vitamin A deficiency. Arch Ophthalmol 1987;105:1224-28.
19. Amédée-Manesme O. Luzeau R. Wittpenn IR, Hanck A, Sommer A. Impression cytology detects subclinical vitamin A deficiency. Am J Clin Nutr 1988;47:875-78.
20. Gadomski AM, Kjolhede CL, Wittpenn J. Bulux 1, Rosas AR, Forman MR. Conjunctival impression cytology (CIC) to detect subclinical vitamin A deficiency: comparison of CIC with biochemical assessments. Am J Clin Nutr 1989;49:495-500.
21. Kjolhede CL, Gadomski AM, Wittpenn J. et al. Conjunctival impression cytology (CIC): feasibility of a field trial to detect subclinical vitamin A deficiency. Am J Clin Nutr 1989;49:490-94.
22. Feachem RG. Vitamin A deficiency and diarrhoea: a review of interrelationships and their implications for the control of xerophthalmia and diarrhoea. Trop Dis Bull 1987;84:RI-R16.

Vitamin A, immunocompetence, and infection

Ranjit K. Chandra and Devhuti Vyas

The interactions between nutrition, immunity, and infection have been the focus of much recent work. It has been observed that protein-energy malnutrition (PEM) is associated with impaired immunocompetence [1-3], including depressed cell-mediated immunity, phagocyte dysfunction, decreased levels of complement components, reduced mucosal secretory antibody responses, and lower antibody affinity. At the same time, the complexity of clinical malnutrition is recognized. This has led to the examination of immunological effects produced by single nutrient deficiencies.

Among other nutrients, vitamin A has a profound effect on immune responses in man and laboratory animals. In humans, vitamin-A deficiency seldom occurs in isolation; it is usually associated with varying degrees of PEM. In many countries there is a high prevalence of xerophthalmia and night blindness among infants and children suffering from PEM. However, the numerical association between PEM and xerophthalmia varies enormously in different geographical regions of the world, from 75% in Indonesia to 32% in India, 1%-6% in Latin America, and 1%-2% in Lebanon and Uganda. However, it is possible that patient selection and subjective diagnostic criteria have influenced the reported low prevalences. Besides low dietary intake, reduced absorption of vitamin A in PEM can further aggravate its deficiency. Oral water-miscible vitamin A is absorbed in an erratic fashion in children with kwashiorkar. A study carried out in South Carolina showed that 50% of underprivileged preschool children of a poor income group had either low or marginal levels of serum vitamin A [4]. Thus, vitamin-A deficiency is not completely restricted to underprivileged or developing countries but has worldwide prevalence and is the third most frequent nutritional problem after

PEM and iron deficiency. It is the most frequent cause of preventable blindness. This has led to international efforts at prevention by periodic massive doses using oral or injectable vitamin A. The rapidity with which vitamin A is absorbed is one of the determinants of early recovery from night blindness and xerophthalmia.

Vitamin A and infection

High death rates among PEM children parallel their vitamin-A status: children dying of PEM have lower levels of vitamin A than the survivors [5]. Most of the deaths are due to respiratory and gastrointestinal infections. It was observed in one study that the overall mortality rate in victims of PEM was 15%, whereas it was as high as 80% if malnutrition was associated with xerophthalmia [6]. The association between hypovitaminosis-A and bacterial and viral infections in humans and various species of animals has been reviewed [7-9]. Many pathological mechanisms probably contribute to the increased risk of infection in vitamin-A deficiency, including tissue changes and altered specific and non-specific immunity. Furthermore, infection itself can aggravate vitamin-A deficiency.

Other than its well-recognized role in rhodopsin synthesis and vision, vitamin A also regulates differentiation of epithelial tissues and inhibits keratinization. In hypovitaminosis-A, the secretory epithelia of respiratory tract and salivary and prostate glands show keratinization; this change offers less resistance against penetration of infectious agents and makes the individual susceptible to infections. Our recent studies indicate that bacteria bind to respiratory epithelial cells in greater numbers in vitamin-A-deficient subjects than in healthy controls (table 1) [10]. Increased mortality has been noted in children with mild vitamin-A deficiency [11]. Vitamin-A deficiency and infections aggravate each other, as the deficiency predisposes the host to infection, which in turn decreases the intestinal absorption of the vitamin [12]. Infection can even precipitate the symptoms of deficiency in an individual with marginal levels of the vitamin. In partially vitamin-A-deficient rats, even a subclinical load of malarial parasites has been shown to precipitate deficiency symptoms at a faster rate and resulted in more severe parasitaemia [13]. Vitamin-A-deficient patients sometimes develop xerophthalmia in only one eye, possibly because of the presence of infection in one site. Nasal mucosa of vitamin-A-deficient chicks keratinized only in areas of virus infection [14]. From these observations, one can deduce that the effects of deficiency are compounded if there is an accompanying infection. In germ-free environments, vitamin-A-deficient rats live for a relatively long time; it is believed that the vitamin requirement is low in the absence of stress of infection [15].

TABLE 1. Clinical data and bacterial binding to epithelial cells

Group	Number			Age (months)	Serum retinol (m mol/L)
	Total	Boys	Girls		Mean	Range
I	14	8	6	22 ± 3	2.234 ± 0.28a	1.413-3.351
II	10	6	4	24 ± 4	1.117 ± 0 14b	0.733-1.397
III	12	7	5	20 ± 3	0.419 ± 0.10c	0.139-0.698

 

Group	Dietary Vitamin A (retinol equivalents)	Ocular signs (number of subjects)			Weight for height (% of standard)	Bacteria per epithelial cell
		Xerophthalmia	Bitot's spots	Corneal opacity
I	321±44a	0	0	0	81±4	4.8±0.6a
II	201±29b	4	2	1	77±3	7.9±1.0b
III	186±22b	9	6	4	74±5	10.3±0.8c

Data are given as mean ± SE.
Values in the same column designated by different superscript letters differ significantly from each other at a probability level of .01 or less.

Mucosal immunity

Secretory antibody response, mucosal cell-mediated immunity, and non-specific barrier functions are important host defences. The disastrous effect of infection in vitamin-A-deficiency state may be due to the increased pathogenicity of infectious agents and/ or reduced immunocompetence of the host. Hypovitaminosis impairs tissue integrity by permitting keratinization of mucociliary linings. In the intestine, a reduction in the number of goblet cells and in mucus production disrupts non-specific defence mechanisms of the gastrointestinal tract. Impaired barrier function increases the systemic spread of infectious agents. By exposing vitamin-A-deficient rats to the nematode Angiostrongylus cantonensis, it was shown that the penetration power of the larvae increased and the animals had a higher worm burden and shorter survival period [16]. The observed effect was not due to inanition, as the animals were tube fed with a vitamin-A-deficient diet. Vitamin-A-deficient chicks after Newcastle disease virus infection had 100 times more virus in the throat swabs than normal non-deficient chicks [17]. The high frequencies of respiratory and gastrointestinal tract infections in PEM may in part be due to tissue changes resulting from associated vitamin-A deficiency.

Reduced levels of secretory IgA (slgA) have been observed in the saliva, nasopharyngeal secretions, duodenal fluid, and tears in malnourished children [18-21]. slgA antibody response to polio virus and measles vaccines is impaired [18]. Intraepithelial Iymphocytes and slgA-secreting plasma cells have been shown to be numerically lower in malnourished patients [22]. Also, levels of slgA in the intestinal fluid of rats on vitamin-A-deficient diets were reported to be very low compared with those in normal animals: rats given 5 mg retinoate per gram of diet showed a maximum of 180.2 mg of slgA per millilitre of intestinal fluid, and withdrawal of retinoic acid resulted in a low level of 46.0 mg of slgA per millilitre [23]. Moreover, it was also shown that supplementation to the deficient animals of 500 mg of retinyl palmitate per day, for just two days, increased the levels of slgA to 148.5 mg per millilitre of intestinal fluid. Intestinal cells of the deficient animals did not show any decrease in immunofluorescence for secretory component in the initial period of deficiency, but, after eight days and more, decreased intensity of fluorescence staining was observed. In addition, vitamin-A-deficient animals showed poor anti-dinitrophenyl response to 2,4-dinitrophenylated bovine gamma globulin (50 mol DNP per mole BOG) fed through tap water after initial priming with an intraperitoneal injection. In fact, only one of seven deficient rats showed a detectable anti-DNP activity, but three of four control animals responded to the antigen. The only deficient rat that responded to the antigen had significantly low levels of antibody (7.4 pmol antibody combining site per millilitre of intestinal fluid) compared with that of controls (18.9 pmol antibody combining site per millilitre).

There are few data on cell traffic in vitamin-A deficiency. Mesenteric Iymph node lymphocytes (MLNL) are precursors of intestinal IgA-secreting plasma cells and have a tendency to localize selectively in the gut mucosa. Protein-deprived rodents show reduced localization of MLNL in the gut. McDermott et al. [24] have shown that PEM and vitamin-A deficiency alter the capacity of MLNL to localize in the gut. Weanling rats were fed a low-vitamin-A diet until growth ceased, but there was no evidence of xerophthalmia or alteration in intestinal mucosa. Labelled Iymph node cells of normal or vitamin-A-deficient animals were injected into normal or vitamin-A-deficient recipient animals. Localization to the gut was decreased irrespective of the nutritional status of the recipients. However, the separate effects of vitamin A and PEM were not clearly dissected out in this study [25]. Reduced homing of MLNL in PEM and vitamin-A deficiency might be one of the reasons for reduced sIgA levels in this nutrient deficiency.

Increased keratinization, low levels of mucus secretion, and decreased numbers of goblet cells in the intestine in vitamin-A deficiency, together with reduced slgA secretion and reduced local antibody response, act synergistically to make the deficient individual vulnerable to a variety of gastrointestinal and respiratory infections. In addition, because of compromised systemic immunocompetence, such an individual may succumb to repeated and chronic infections [26; 27].

Phagocytes

Once the infectious agent crosses the anatomic barriers of skin and mucous membrane and enters the body, phagocytes deal in a non-specific way with certain bacteria and fungi before antigen-specific cellular and humoral immune mechanisms come into play. Large doses of vitamin A given to normal mice have been shown to offer non-specific resistance to grampositive and gram-negative bacterial and fungal infection [28]. A decreased mortality rate and low levels of bacteraemia were reported after challenge with Pseudomonas aeruginosa, Listeria monocytogenes, and Candida albicans. It was concluded that this increase in resistance is non-specific and might result from an augmented capacity of phagocytes (macrophages) to deal with these agents. However, there was no change in the uptake of colloidal carbon or aggregated human serum albumin by the reticuloendothelial system. The effect could not be due to changes in the organisms themselves, since vitamin A did not alter in vitro growth rates of the three microorganisms.

Hof and Emmerling [29] also observed a 100-fold increase in resistance to infection with L. monocytogenes. This was seen during the early stage of infection and was therefore attributed to increased functional capacity of the phagocytic system in rats treated with vitamin A. However, it should be noted that very large toxic doses (4 x 15,000 IU) of retinoic acid had to be used ro achieve such protective effects. Vitamin-A-deficient and PEM rats were shown to have a reduced number of glass-adhering cells (macrophages), and, moreover, these phagocytes had decreased ability to clear infection with a malarial parasite, Plasmodium berghei. Oral supplementation of vitamin A to deficient rats after infection has been shown to augment the recovery process [14]. Survival time after infection was shorter in vitamin-A-deficient animals than in pair-fed animals, but in control animals no death occurred during the experimental period of five weeks.

Lymphoid tissue

An impaired immune system is one of the factors that add to the vulnerability of vitamin-A-deficient individuals to infection. Usually vitamin-A deficiency occurs concomitantly with PEM, and in experimental animals vitamin-A deficiency causes inanition. There is ample evidence of reduced immunocompetence in PEM [1-3]. If PEM is accompanied by vitamin-A deficiency, the deficiency adds significantly to susceptibility to infection because of its additional detrimental effects on Iymphoid tissues and organs [30-35].

A diet deficient in vitamin A has been shown to cause atrophic changes in the thymus and spleen in rats [30]. Pair-fed rats that developed PEM also showed atrophic changes in bath tissues, but the magnitude of change was much greater in the vitamin-A-deficient group. The cortical region of the thymus of vitamin-A-deficient animals becomes devoid of Iymphocytes. The spleen also shows atrophy of germinal centers. However, Chandra and Au [31] observed only a slight difference in weight of the thymus and spleen from vitamin-A-deficient and pair-fed control animals, though the weights were significantly different Mom those of control animals fed ad libitum (table 2). These results suggest that the observed effect is mainly due to anorexia and malabsorption associated with vitamin-A deficiency. Similarly, Nauss et al. [36] also observed that weights of the spleen and thymus of vitamin-A-deficient and pair-fed controls were comparable but were lower than those from controls fed ad libitum.

TABLE 2. Organ weights

	No.	Thymus	Spleen
Group	of	weight	weight
	rats	(mg)	(mg)
Vitamin-A-deficient	6	181 ± 39	317 ± 41
Pair-fed control	6	208 ± 28	339 ± 47
Ad libitum control	6	281 ± 40	387 ± 59

Source: Ref. 31.

Involution of the thymus and bursa of Fabricius have been observed in vitamin-A-deficient chicks [33]. Chickens on a vitamin-A-deficient diet from the time of hatching showed atrophic changes in Iymphoid tissues. After 30 days on a vitamin-A-deficient diet, the epithelium of the bursa of Fabricius became pseudo-stratified, or cystic, and was disorganized compared with normal tissue. Follicles also displayed irregularity and fibrosis. The medulla showed invasion by heterophil cells, which replaced Iymphocytes. Panda and Combs [37] also observed a decrease in weight of bursae in vitamin-A-deficient chicks. Infection of deficient chicks by Newcastle disease virus caused further regression of bursae, interfollicular fibrosis, epithelial metaplasia, and keratinization. Follicles showed loss of lymphocytes and invasion of polymorphonuclear leukocytes and eosinophils five days after infection, and the medulla showed debris of disintegrating cell nuclei. These atrophic changes were progressive, and after nine days of infection, bursae of vitamin-A-deficient chicks were significantly different from those of vitamin-A-deficient non-infected controls. The thymus of vitamin-A-deprived chicks showed invasion of polymorphonuclear cells and loss of cortical width. After one day of virus infection, thymic corpuscles increased in size and number, and the cortex decreased in size and showed cell debris. These changes were progressive: Three days after infection a complete loss of cortex became evident, as shown by a reticular epithelial mesh, and thymic corpuscles showed dilation and degeneration. After seven days the organ appeared devoid of thymocytes and showed thymic corpuscles, degenerating cells, thick-walled vessels, and vacuoles containing polymorphonuclear cells. Atrophic changes were modest in the noninfective vitamin-deficient state [33]. Thus, vitamin deficiency and infection had synergistic effects on the Iymphoid tissue, thereby increasing the severity of the course of infection.

It is evident that vitamin-A deficiency causes atrophic changes in Iymphoid tissue. At the same time, a high dose of retinoic acid (1,000 fig per mouse per day for seven days) also resulted in reduction in body weight and spleen weight; it affected cell populations in the spleen and thymus, but the bone marrow was more or less resistant to this toxic effect. The thymus and spleen showed 95% and 50% reduction in cellularity respectively when high doses of retinoic acid were used [34].

T cells

In clinical practice, it is difficult to sort out the individual effects of vitamin-A deficiency from those of other nutrient deficiencies. The frequent presence of PEM confounds the picture. Thus, the reported reduction in the number of T cells [35] may well be due to concomitant PEM rather than to vitamin-A deficiency itself. In rodents fed a low-vitamin-A diet, the level of serum thymic factor is unaltered [32]. A decreased total leucocyte number has been observed in vitamin-A deficiency; the differential count revealed a relative increase in neutrophils and a decrease in the number of Iymphocytes. The mitogenic response of splenic Iymphocytes of vitamin-A-deficient rats to phytohaemagglutinin, concavalin A, and Escherichia coli lipopolysaccharide is reported to be less than one-third that of control and pair-fed animals [31; 36], although the mitogenic response of thymic Iymphocytes to concavalin A was comparable in vitamin-A-deficient, pair-fed, and control animals studied by 3H incorporation. Vitamin-A supplementation for three days was shown to increase circulating Iymphocytes and to restore the mitogenic response of splenic Iymphocytes to normal levels [36]. Decreased 3H incorporation by thymacytes and splenocytes was also reported in vitamin-A-deficient and PEM rats [30].

Decreased nucleic acid synthesis and mitogenic response (table 3) may be due to defective synthesis of membrane receptors. Marked changes in glycoprotein synthesis have been observed in vitamin-A deficiency [38; 39], and similar changes in membrane glycoproteins of lymphocytes (R. K. Chandra and V. Kumar, unpublished data) may contribute to impaired cell-mediated immunity seen in vitamin-A deficiency. Alternatively, if changes in T cells in vitamin-A deficiency are accompanied by increased suppressor T cells, then decreased mitogenic response would also result.

TABLE 3. Mitogen stimulation response

Stimulation index
PHA (µg)a	Vitamin-A- deficient rats (N = 6)	Pair-fed controls(N = 6)	P value
0.2	20.7 ± 8.8	87.8 ± 39.5	<.05
0.5	37.5 ± 19.0	104.8 ±36.4	< .01
2.0	38.7 ± 31.9	121.8 ±57.5	<.01

Source: Ref. 31. a. Amount of phytohaemagglutinin (PHA) in each well of microtitre plate.

In human volunteers, a modest supplement of beta-carotene is associated with increase in the number and function of CD4+ helper T cells. If this translates into enhanced resistance, it would have immense clinical significance. Vitamin-A supplementation has been shown to augment cell-mediated immune response, and injections of 150 IU per gram per day for five days accelerated the onset and decreased the duration of skin-graft rejection in mice [40]. Mice treated with 150 mg of vitamin A and sheep red-blood cells (SRBC) simultaneously and challenged 3-21 days later with the same antigen by subcutaneous injection into the pinna showed increased cell-mediated immune response measured as an increase in the thickness of the ear [41]. Conversely, it has been reported [34] that mice treated with 25 and 50 mg of retinoic acid, primed with SRBC, and then challenged later with SRBC into the footpad did not show any increase in levels of cell-mediated immune response measured as an increase in footpad diameter. Moreover, 100 and 300 mg of retinoic acid slightly suppressed the delayed hypersensitivity reaction. The discrepancy in the results of the two groups of investigators might be due to differences in the design of the experiment, particularly the dosage of retinoic acid and the time of its administration. In one study [41], vitamin A and SRBC were injected simultaneously, and, in the other [34], retinoic acid was injected for 1-6 days and the animals were primed with SRBC on day 10. Retinoic acid was shown to have no stimulatory effect on the mixed lymphocyte reaction in mice [34].

B cells

Vitamin A also modified the humoral response, especially to T-dependent antigens. The number of plaque-forming cells in vitamin-A-deficient rats was lower than in pair-fed animals (table 4) [31]. Haemagglutinin titre against diphtheria and tetanus antigens were found to be reduced in vitamin-A-deficient rats as compared with pair-fed controls [30]. Another study showed increased haemagglutinin titre to SRBC in mice after treatment with 600 IU of vitamin per gram of body weight per day for five days, either before or shortly after sensitization with antigen [40]. The response to vitamin-A treatment was highly significant: the relative reciprocal titre of haemagglutininin the controls was 64 and in the vitamin-A-treated animals was in the range 1,024-4,096.

TABLE 4. Plaque-forming cell response

Direct PFC per spleen (10 -3)	Vitamin-A- deficient	Pair-fed controls	P value
rats (N = 6)	(N = 6)
Background	0.39 ± 0.08	0.24 ± 0.09	<.05
Day 5 after	17.5 ± 4.8	56.4 ± 9.0	<.01

Source: Ref. 31.

Cohen and Cohen [42] have also reported increased plaque-forming cells to SRBC in vitamin-A-treated mice. They showed that intraperitoneal administration of 1,000 IU of vitamin A per day for four days increased plaque-forming cells. The maximum effect (a fivefold increase) was observed with a dose of 300 IU per day for four days; the toxic dose of 9,000 IU per day did not increase antibody-forming cells in the spleen of mice. Increased antibody production to 2,4-dinitrophenyl conjugate of ovalbumin after two subcutaneous injections of either 2,000 or 5,000 IU of vitamin A was also observed in mice [42].

Partial vitamin-A deficiency in chicks reduces agglutinin titre against Salmonella pullorum antigen [35]. Uhr et al. [43] have reported an immunosuppressive effect of vitamin A in guinea pigs. They did not find any increase either in the clearance of bacteriophage ox174 from the circulation or in the production of antibodies to it. However, they observed prolonged production of 19S antibodies if vitamin A was injected simultaneously with antigen [44]. Dennert and Lotan [34], in studies in vitro, observed 80% reduction in plaque-forming cell response of spleen cells from retinoic-acid-treated mice, and 10^-5-10^-9 M concentration of retinoic acid during sensitization of spleen cells to SRBC was shown to completely suppress the induction of plaque-forming cells. In viva studies showed no effect of 100, 300, and 1,000 fig of retinoic acid for five days and sensitization with SRBC on day 4 on the number of plaque-forming cells in the spleen after eight days.

In mice, the simultaneous administration of vitamin and tetanus toxoid resulted in an enhanced antitoxin response. The effect of three different doses of vitamin A (3,000, 25,000, and 30,000 IU) in mice on the antitoxin response to tetanus toxoid indicated a direct relation of the response to the dose of vitamin [45]. Comparable doses of vitamin A given to children would have had undesirable side effects. At the dose level of 30,000 IU, mice showed signs of toxicity. However, these investigators did not observe any significant effect of 200,000 IU of vitamin A on the production of antitoxin to tetanus toxoid in a field trial involving Bangladeshi children.

Complement

In PEM, in addition to a decrease in cell-mediated and humoral immune responses, haemolytic complement activity of the serum is depressed. Vitamin-A deficiency has been shown to aggravate the disastrous effects of PEM on immunocompetence. However, in rats, vitamin-A deficiency did not have any additive effect on serum complement levels in PEM. Contrary to the case with PEM, in which complement levels decrease [1-31, vitamin-A deficiency has been shown to enhance complement levels [46]. In addition to this, Azar and Good [47] have shown suppression of serum complement haemolytic activity 24 hours after a large dose of vitamin A is administered.

Adjuvant effects

Vitamin A acts as an adjuvant at non-toxic doses and enhances cell-mediated and humoral immune responses. Injections of vitamin A increased the cellularity of redonal Iymph nodes.[48]. The vitamin has also been shown to stimulate antibody production to bovine gamma globulin, which would otherwise have resulted in immunological paralysis [49]. The adjuvant property of vitamin A was thought to be due to its membrane-labilizing effect on Iysosomes. Lysosomal membrane labilization can induce Iymphoid cell proliferation [50]. Vitamin A has been shown to enhance cell-mediated immune response when administered simultaneously with or close to the antigen challenge. Moreover, injection of vitamin A at a site remote from that of the antigen was shown to be ineffective in enhancing cellular immunity [40; 41], suggesting that the draining Iymph node might be the site of adjuvant action of vitamin A. Taub et al. [48] reported on the adjuvanticity of vitamin A. Two days after injection of 0.5 mg of vitamin A in liquid paraffin in the right footpad, the popliteal Iymph node showed enlargement and hypercellularity of paracortical areas. After six days, the germinal centres were observed in the cortex, and the medullary region showed slight expansion and a few place cells. Vitamin A was shown to work as a classic adjuvant without any antigenicity. The formation of germinal centres after vitamin-A administration was not as pronounced as with other adjuvants, such as alum-precipitated bovine gamma globulin, Freund's complete adjuvant, and pertussis coccobacillus. Enlargement of the Iymph node and increased Iymphocyte traffic after vitamin-A treatment close to the time of antigen treatment may help to augment immune response by increasing contact between lymphocytes and antigens. Allison and Davies [51] have also shown cellular proliferation and blast transformation in thymus-dependent areas of a draining Iymph node after vitamin-A administration.

Concluding remarks

The world-wide prevalence of isolated vitamin-A deficiency and its occurrence in association with other nutritional deficiencies, especially PEM, and with infection has stimulated considerable recent work on the role of vitamin A in host resistence. Vitamin A subserves a number of important physiological functions that contribute to effective immunocompetence. Moderately large doses of beta-carotene have an immunostimulatory effect and can reverse the suppression produced by pharmacological agents such as cortisone. It acts as an adjuvant and influences both cell-membrane and intracellular composition and function. This applies to Iymphocytes and monocytes. Thus, it is reasonable to expect that vitamin-A deficiency is associated with an increased incidence of infection and that its prevention or treatment will result in decreased illness. This may be due to epithelial changes and improved cell-mediated and mucosal immunity. Recent work [26; 27; 52-55] has affirmed the critical role of beta-carotene and vitamin A in optimum immunocompetence. At the same time, massive doses of vitamin A if given for prolonged periods may have a deleterious effect.

Acknowledgements

Our work has been supported by Health and Welfare Canada, the Medical Research Council, Ross Laboratories, Sandoz Nutrition, and the Carnation Company.

The present article is based on an earlier review article l27].

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Effects of vitamin-A status on hamster tracheal epithelium in viva in vitro

Luigi M. De Luca and Elizabeth M. McDowell

This paper highlights what is known about how vitamin A and the retinoids control epithelial morphology and function. The system of choice is the tracheal epithelium of the Syrian golden hamster. This species was originally selected by Saffiotti et al. [1] in their studies of chemical carcinogenesis of the respiratory tract because it is relatively resistant to respiratory infection. The system was then rendered more amenable to in vitro investigation by Sporn et al. [2], who defined conditions for maintaining the trachea in organ explant culture, as well as the tissue's requirement for retinoic acid (RA) in the maintenance of normal mucociliary differentiation. Following in viva observations [3; 4], McDowell et al. have recently used epithelial cell culture techniques to define the mucous cell as the target of vitamin A [5].

In vivo effect of vitamin-A status on the hamster tracheal epithelium

The final effect of nutritional deficiency of vitamin A on the tracheal epithelium is the replacement of ciliated cells and normal mucous cells (fig. 1) by squamoid cells (altered mucous cells), which normally characterize the epidermoid type of differentiation. Figure 2 shows the extent of such replacement, which results in the near occlusion of the tracheal lumen. Accumulation of bacteria and other external material influences survival of the animal, which eventually succumbs to infection.

The terminal stage is preceded by primary effects of the deficient diet. Careful monitoring of the changes in body weight and serum retinal levels allowed the definition of a stage of "minimal morphological change," which preceded the loss of body weight [3; 4; 6]. Measurement of the cell-division rates in the mucous and basal cells during the development of vitamin-A deficiency revealed that the rates (mitotic rates) were lowered in a non-uniform manner. The replication of mucous cells was profoundly reduced compared with that of the basal cells during the stage of "minimal morphological change." This is clearly shown in table 1.

This work leads to the conclusion that vitamin-A deficiency depresses epithelial cell division before epidermoid metaplasia formation is evident. If vitamin-A deficiency continues, however, the altered mucous cells regain the capacity to divide and the epithelium is replaced by flat "squamoid cells." These cells generally arise as a consequence of cell injury, whether caused by carcinogen exposure, mechanical injury, or, as in this case, nutritional deficiency (fig. 3). It is clear, then, that squamoid cells (but not columnar mucous cells) can survive and multiply in the absence of vitamin A. Reversal of squamous metaplasia to the normal mucociliary phenotype of the tracheal epithelium is only possible in the presence of vitamin A or one of its biologically active analogues.

TABLE 1. Proportions and mitotic rates of tracheal basal, mucous, and ciliated cells of control and vitamin-A-deprived hamsters

Cell type	Control	Vitamin-A-deprived	P value
Proportion of total (%)
Basal	28.7 ± 2.5	39.7 ± 2.7	<.0001
Mucous	59.3 ± 2.6	53.1 ± 1.9	<.001
Ciliated	11.0 ± 3.1	6.8 ± 1.8	<.05
Mitotic rate (% of total)a
Basal	0 61 ± 0.13	0.29 ± 0.35	<.062
Mucous	2.42 ± 1.19	0.15 ± 0.10	<.01
Ciliatedb	0	0
Mitotic rate (% of own cell type)c
Basal	2.14 ± 0.48	0.72 ± 0.91	<.01
Mucous	4.06 ± 1.97	0.29 ± 0.2	<.01
Ciliatedb	0	0

Source: Ref. 4 Reproduced by permission.

The data for vitamin-A-deprived cells were derived from epithelia showing minimal changes after five weeks on diet. Foci of stratification and/or epidermoid metaplasia (about 5% of all epithelial cells) were excluded from the analysis.
a. Mean percentage of total number of epithelial cells counted in cross-section of two tracheal rings per hamster (about 1,600 cells). Each hamster received 3H-thymidine and colchicine six hours before sacrifice.
b. Ciliated cells do not divide.
c. Mean percentage of total number of basal cells or mucous cells.

Administration of retinyl acetate to vitamin-A-deficient hamsters, again, primarily affects cell division of the mucous cells (fig. 4). Within three days their cell-division rate returned to normal levels. The number of preciliated cells, which are progeny of replicating mucous cells, was restored to normal levels, but vitamin-A repletion had no effect on the replication of the basal cells.

The first unequivocal conclusion from this in viva work is that vitamin A is necessary to maintain normal rates of mucous cell division in the tracheal epithelium.

FIG. 4. Relationship between the proportion of. preciliated cells and the mitotic rates (M.R.) of mucous cells and basal cells All data represent mean percentages of the total number of epithelial cells counted. Control values were 0.39% for the proportion of preciliated cells and 0.61% and 2.2% for the mitotic rate of basal cells and mucous cells respectively.

In vitro cell culture work

Recent work is] has permitted observation of the effects of vitamin-A depletion in cultured epithelial cells from hamster tracheas. The cells recapitulated the development of normal epithelium during seven days of culture. In the presence of retinoic acid, the mucous cells divided at a high rate and the progeny rapidly matured to fully differentiated mucous and ciliated cells (fig. 5). Smaller cells were also visible in the culture and probably represented basal cells found in viva. The study compared the morphology and cell-division rates of the cells in the presence and absence of retinoic acid. It is clear from figure 6 that deficiency of vitamin A markedly lowered the ability of the larger mucous cells to divide.

FIG. 6. The effect retinoic-acid (RA) depletion on ³H-thymidine-labelled nuclei of small (basal) and large (secretory) tracheal epithelial cells - percentages of each kind of cell. The large cells were very flat in RA- cultures on days 2 and 4, and so it was possible to discriminate between the nuclei of the two kind of cells

When cells grew in the absence of retinoic acid on collagen substrate, they failed to mature into normal columnar mucous cells and, instead, showed the squamous type of differentiation characteristic of vitamin-A deficiency in vivo and of organ-cultured epithelium (fig7).

This in vitro work confirms the notation that retinoic acid in required for cell division and differentation of mucous cells.

The control of mucus production by vitamin A

In conjunction with the lowered rate of mucous cell division, vitamin-A deficiency also causes a decrease in periodic-acid Schiff base (PAS)-positive cells, which indicates less production of mucus. Whether this precedes or follows the decrease in cell division is unclear, but it certainly appears to precede the enhancement of keratin production in the trachea.

Squamous metaplasia is not observed in the small intestine, even in severe vitamin-A deficiency [7]; however, mucin biosynthesis, as measured by the incorporation of 3H-glucosamine, is decreased [8]. We were able to raise an antibody to the purified goblet cell glycoprotein [9]. Indirect immunofluorescence studies clearly indicated the presence of a cross-reactive antigen in a variety of rat epithelial tissues. Vitamin-A deficiency caused a marked drop in the amount of cross-reacting antigen in a variety of epithelial tissues, including the trachea [10]. Therefore, we can conclude that, in addition to cell division of mucous cells, vitamin A also controls mucus production.

Vitamin-A control of keratin gone expression

A later event during the progression of vitamin-A deficiency is keratin gene activation and consequent keratin production. A co-ordinated expression of acidic and basic keratins takes place in vitamin-A deficient hamster tracheas [11]. These keratins are not readily detectable in hamsters fed vitamin A or in tracheas cultured in the presence of retinoic acid. Notwithstanding the morphological similarity between the epidermis and the squamoid epidermoid tracheas, keratin gene products expressed in vitamin-A-deficient tracheas are not the same as in the skin. One outstanding difference is that keratin 1 (67,000 daltons), a prominent epidermal keratin, is not produced in vitamin-A-deficient tracheas [11].

Carcinogenesis

Exposure to chemical carcinogens, such as benzo[a]pyrene and 7,12-dimethylbenz[a]anthracene, causes similar squamous metaplastic lesions in the trachea [12]. When tracheas from four-week-old hamsters fed a normal diet were cultured in the presence of either benzo[a]pyrene or 7,12-dimethylbenz[a]anthracene for two weeks without retinoic acid, they developed squamoid metaplastic lesions. These lesions were not visible when retinoic acid was included in the medium containing the carcinogens (F. L. Huang et al., in preparation). Thus, clearly, retinoic acid is capable of repairing the squamoid metaplasia caused by carcinogen exposure. The squamoid lesions caused by the presence of the carcinogen were also positive by immunofluorescence with keratin antibodies (F. L. Huang et al., in preparation).

Importance of nutritional status in histogenesis: The concept of exotrophism

Organisms capable of synthesizing various essential nutrients are said to be prototrophic for those nutrients. Neurospora is an organism that is prototrophic for pantothenic acid, among other nutrients. When Neurospora is treated with a mutagenic dose of ultraviolet radiation, the result may be the establishment of a requirement for pantothenic acid in the offspring, which is said to have become a "pantothenic-acid auxotroph." Utilizing this approach, Beadle and Tatum [13] have elucidated the steps involved in the biosynthesis of various essential nutrients. Thus, auxotrophism is defined by the need for the exogenous supply of a nutrient in the presence of a mutated phenotype [14].

The mucociliary tracheas, or other epithelia, need vitamin A to maintain their differentiation. The tracheal squamoid cell, which prevails under conditions of vitamin-A deficiency, however, apparently does not need the vitamin. We propose to call this squamous cell "exotrophic" for vitamin A, that is, as having escaped the vitamin-A-requiring status normally characteristic of the columnar epithelium of the trachea. In the presence of vitamin A, this cell is replaced by the normal columnar cells. If, however, the supply of the vitamin is scarce, a conditional "vitamin-A exotroph," that is the squamoid cell, may persist at the site. This exotroph may become permanent by the action of a mutagenic agent, which would fix the exotrophic state, as shown schematically in figure 8. It is then possible to postulate that, when subject to the action of carcinogens and/or tumour-promoting substances, fixed exotrophic cells might divide and contribute to a tumour.

Figure 8

What is the advantage of the exotrophic state to the tumour cell? Quite simply that it has bypassed the requirement for the essential substance and thus the stringency of normal growth control. A cell can become more autonomous as it bypasses the requirements for more essential nutrients. The end result would be a cell that has been liberated from the usual constraints of regulatory substances and that may eventually prevail over other, normally regulated cells.

We and others have examined hepatoma cells and have found that, in general, they contain very little if any retinyl palmitate, whereas the surrounding hepatic host tissue contains normal concentrations of retinyl palmitate [15]. Transplanted hepatomas, whether minimally or maximally deviated from normal, are devoid of retinyl palmitate, whereas the host rat liver tissue and regenerating liver contain normal levels of the vitamin (table 2). Naturally, the lack of detectable retinyl palmitate in hepatoma tissue may be due to a variety of reasons, which are not mutually exclusive, among which are the following:

• The hepatoma cell may destroy vitamin A as it comes in contact with it, as suggested by the findings of Muto et al. [16] that some hepatomas may form anhydroretinol from retinol. - The deficiency may be the result of defective transport for retinol.
• A hepatic retinol exotroph may be the stem cell of hepatomas.

TABLE 2. Retinyl palmitate of hepatoma, host rat and regenerating liver postnuclear membranes (nanograms per milligram of protein)

	Liver	Tumour
20-1-1	580 ± 30	<1.6
16-2-1	513 ± 52	<1.6
7787-1-1	400 ± 21	<1.6
9618A-1-1	942 ± 2.2	<1.6
44-1-2	547 ± 21	<1.6
5123D-1-1	150 ± 3.8	<1.6
3924A-1-1	177 ± 59	<1.6
7800-1-1	73 ± 1.8	<1.6
5123 tc 1-2	363 ± 6.7	<1.6
7777-2-1	243 ± 38	<1.6
Primary cystic tumour	302 ±28	<1.6
Regenerating liver
24 hours	113 ± 7
48 hours	100 ±10

Summary and conclusions

In this paper we have suggested the new concept of exotrophic cells, i.e. cells that have conditionally escaped the need for an essential nutrient, such as vitamin A. These exotrophs might become fixed by a mutation and eventually contribute to the tumorigenic phenotype.

The discovery of the retinoic acid receptor (RAR) has opened up new horizons in the search for the mechanism of action of retinoic acid [17; 18]. It is intriguing that a second retinoic acid receptor, RARE, is abundantly expressed in hepatoma tissue and not in normal liver; Benbrook et al. [191 suggest that the erroneous expression of the RARE might contribute to tumour development in liver. How and whether these findings relate to the vitamin-A-deficient status of hepatoma cells remains to be understood.

References

1. Saffiotti U. Montesano R. Sellakumar AR, Borg SA. Experimental cancer of the lung: inhibition by vitamin A of the induction of tracheobronchial squamous metaplasia and squamous cell tumors. Cancer 1967;20:85764.
2. Sporn MB, Dunlop NM, Newton DL, Smith JM. Prevention of chemical carcinogenesis by vitamin A and its synthetic analogs (retinoids). Fed Proc 1976;35: 1332-38.
3. McDowell EM, Keenan KP, Huang M. Effects of vitamin A-deprivation on hamster tracheal epithelium: a quantitative morphologic study. Virchows Arch B 1984;45:197-219.
4. McDowell EM, Keenan KP, Huang M. Restoration of mucociliary tracheal epithelium following deprivation of vitamin A: a quantitative morphologic study. Virchows Arch B 1984;45:221-40.
5. McDowell EM, Ben T. Coleman B. Chang S. Newkirk C, De Luca LM. Effects of retinoic acid on the growth and morphology of hamster tracheal epithelial cells in primary culture. Virchows Arch B 1987;54:38-51.
6. Strum JM, Latham PS, Schmidt ML, McDowell EM. Vitamin A deprivation in hamsters: correlations between tracheal epithelial morphology and serum/tissue levels of vitamin A. Virchows Arch B 1985;50:43-57.
7. De Luca LM, Little EP, Wolf G. Vitamin A and protein synthesis by rat intestinal mucosa. J Biol Chem 1969; 244:701-08.
8. De Luca LM, Schumacher M, Wolf C. Biosynthesis of a fucose-containing glycopeptide from rat small intestine in normal and vitamin A-deficient conditions. J Biol Chem 1970;245:4551-58.
9. De Luca LM, Schumacher M, Nelson DP. Localization of the retinol-dependent fucose-glycopeptide in the goblet cell of the rat small intestine. J Biol Chem 1971 ;246:5762-65.
10. De Luca LM, Maestri N. Bonanni F. Nelson DP. Maintenance of epithelial cell differentiation: the mode of action of vitamin A. Cancer 1972;30:1326-31.
11. Huang FL, Roop DR, De Luca LM. Vitamin A deficiency and keratin biosynthesis in cultured hamster trachea. In Vitro 1986;22:223-30.
12. Harris CC, Sporn MB, Kaufman DG, Smith JM, Jackson FE, Saffiotti U. Histogenesis of squamous metaplasia in the hamster tracheal epithelium caused by vitamin A deficiency or benzo [a]pyreneferric oxide. J Natl Cancer Inst 1972;48:743-61.
13. Beadle GW, Tatum EL. Genetic control of biochemical reactions in Neurospora. Proc Natl Acad Sci 1941; 27:499-506.
14. Ayala FJ, Kiger JA Jr. Modem genetics. 2nd ed. Menlo Park, Calif, USA: Benjamin/Cummings, 1984.
15. De Luca LM, Brugh M, Silverman-Jones CS. Retinyl palmitate, retinyl phosphate, and dolichyl phosphate of postnuclear membrane fraction from hepatoma, host liver, and regenerating liver: marginal vitamin A status of hepatoma tissue. Cancer Res 1984;44:224-32.
16. Muto Y. Moriwaki H. Antitumor activity of vitamin A and its derivatives. J Natl Cancer Inst 1984;73:1389-93.
17. Petkovich M, Brand NJ, Krust A, Chambon P. A human retinoic acid receptor which belongs to the family of nuclear receptors. Nature 1987;330:444-50.
18. Giguere V, Ong ES, Segui P. Evans RM. Identification of a receptor for the morphogen retinoic acid. Nature 1987;330:624-29.
19. Benbrock D, Lernhardt E, Pfahl M. A new retinoic acid receptor identified from a hepatocellular carcinoma. Nature 1988;333:669-72.

Research priorities and strategies for investigation of the influence of vitamin-A supplementation on morbidity

Michele R. Forman

This paper reviews recent clinical and field research in vitamin A and morbidity and examines, primarily, the epidemiologic evidence for the association between vitamin-A deficiency and morbidity. Since I have been requested to discuss the findings from the most significant work, this review is not exhaustive and is based on an epidemiologist's view of significance. From the available literature, most vitamin-A research focuses on the following morbidities: respiratory disease, diarrhoeal disease, and measles complications, of which respiratory and diarrhoeal infections and corneal ulcers are the most common in less-developed communities. The research was designed as either longitudinal cohort studies of pre-school-aged children or hospital-based trials.

For this review, several criteria were used to evaluate individual studies, including the following:

• the strength of the association or effect;
• whether important factors related to vitamin-A status and to morbidity were controlled in the analysis;
• the identification of positive or negative findings and whether any systematic bias could have altered those findings, which are usually computed as an estimate of effect, such as a relative risk; and
• the appropriateness of, as well as the ability to implement, the study design.

A summary of study findings and recommendations for future research follow the review of recent research.

Review of recent research

Prospective cohort studies

Prospective cohort studies of vitamin-A deficiency and respiratory and diarrhoeal disease have been con ducted in central Java, Indonesia, and Hyderabad, India. Neither study, however, was designed as a vitamin-A and morbidity study. In an 18-month longitudinal cohort study of pre-school-aged central Javanese children (N = 4,600), ocular and other clinical data were collected at baseline and every three months for evidence of xerophthalmia and respiratory and diarrhoeal disease; anthropometric data were collected to evaluate nutritional status. The child's ocular status was assessed by an ophthalmologist at each three-month examination. The morbidity data were based on clinical signs of current respiratory disease, diagnosed by a paediatrician at the examination, and the diarrhoeal disease data were based on maternal recall of the child's experiencing four or more loose stools per day at any time during the month prior to the examination.

Two separate sets of analyses have been published from this study [1; 2]. In one set [1] the incidence rates of respiratory disease and the prevalence rates of diarrhoeal disease at the end of each three-month interval were determined for children with and without mild xerophthalmia (Bitot's spots and/or night blindness) at both the onset and end of the cycle. Compared with healthy children without xerophthalmia, those children with mild xerophthalmia at the start and end of a three-month cycle had an almost two and threefold risk of respiratory and diarrhoeal disease respectively (table 1). Age-specific relative risks were not appreciably different for diarrhoeal disease and were varied for respiratory disease. These findings were similar within weight-for-height groups (based on the Waterlow classification).

In the second set of analyses [2], all children without xerophthalmia at the beginning of a cycle were stratified by the presence or absence of respiratory or diarrhoeal disease, and the prevalence of mild xerophthalmia was determined at the following examination three months later. Those children with either respiratory or diarrhoeal disease at the onset of a cycle had 2.2 and 2.5 times as great a relative risk respectively of developing mild xerophthalmia by the " end of the cycle as healthy (non-respiratory/non-diarrhoeal disease) controls (table 2). The excess risk of xerophthalmia among respiratory disease cases was restricted to children three years old and over, and the relative risks of xerophthalmia among diarrhoe al cases versus children without diarrhoeal diseases varied by age. These findings were similar within weight-for-height groups.

TABLE 1. Age-specific incidence of respiratory and diarrhoeal disease among children with and without xerophthalmia

Age (years)	Number of child-intervals		Cases of disease		Rate per 1,000		Relative risk (N-N: X-X)	p (2-tailed)
	N-N	X-X	N-N	X-X	N-N	X-X
Respiratory disease
L 1	5,484	42	470	8	86	191	1:2.2	<.05
2	2 993	143	257	31	86	217	1:2.3	<.001
3	3 051	188	176	21	58	112	1:1.9	<.01
4	3,031	164	100	13	33	79	1:2.4	<.001
3 5	3,644	191	89	5	24	26	1:1.1	NS
Total	18,203	728	1,092	78	60	107	1:1.8	<.001
Diarrhoea
L 1	5,425	36	421	9	78	250	1:3.2	<.001
2	3,014	135	202	31	67	230	1:3.4	<.001
3	3,018	160	151	27	50	169	1:3.4	<.001
4	2,958	147	93	14	31	95	1:3.1	<.001
3 5	3,624	183	87	14	24	77	1:3.2	<.001
Total	18,039	661	954	95	53	144	1 :2.7	<.001

Source: Ref. 1.

N-N: Children with normal eyes at both the start and the end of the three-month observational interval.
X-X: Children with mild xerophthalmia (night blindness and/or Bitot's spots) at both the start and the end of the interval.

TABLE 2. Age-specific incidence of xerophthalmia for children with and without respiratory disease and for children with and without diarrhoea

Age (years)	Child-intervals		Developed xerophthalmiaa		Rate per 1,000		Relative risk ( -: + )
	-	+	-	+	-	+
Respiratory disease
L 1	5,533	595	6	0	1.1	0	-
2	3001	417	8	1	2.7	2.4	1:0.9
3	3061	257	10	3	3.3	11.7	1:3.6
4	3042	170	11	2	3.6	11.8	1:3.3
3 5	3657	137	13	3	36	219	1:6.2
Total	18,294	1,576	48	9	2 6	5.7	1:2.2b
Diarrhoea
L 1	4,990	465	4	2	0.8	4.3	1:5.4
2	3038	289	8	1	2 6	3.5	1:1.3
3	3,045	172	11	1	3.6	5.8	1:1.6
4	2979	151	11	2	3.7	13.2	1:3.6
3 5	3644	93	14	2	3.8	21.5	1:5.7
Total	17,696	1,170	48	8	2.7	6.8	1:2.5b

Source: Ref. 2.

Minus and plus signs indicate the absence or presence respectively of respiratory disease at the examination initiating a three-month interval, or of a history of four or more loose stools a day within the month preceding the examination.

a. Xerophthalmia present at the examination terminating the three-month interval.
b. p < .05,2-tailed.

TABLE 3. Incidence of respiratory disease and diarrhoea for children under five years of age with and without mild xerophthalmia-India and Indonesia

Country and age (years)	Child-intervalsa		Cases of disease		Rate per 1,000		Relative risk (+ X /-X)	p (2-tailed)
	-X	+X	-X	+X	-X	+X
Respiratory disease
India
L 1	1,540	3	153	0	99	0	0.0
2	724	11	49	3	68	273	4.0
3	756	21	36	2	48	95	2.0
4	600	27	29	4	48	148	3.1
<5	3,620	62	267	9	74	145	2.0	.06
Indonesia	14,559	537	1,003	73	69	136	2.0	< 001
Diarrhoea
India
L 1	1.540	3	961	1	624	333	0.5
2	724	11	363	5	501	455	0.9
3	756	21	269	11	356	524	1.5
4	600	27	175	10	292	370	1.3
<5	3,620	62	1,763	27	488	435	0.9	NS
Indonesia	14,415	478	867	81	60	169	2.8	<.001

Source: Ref. 3.

-X: without xerophthalmia. +X: with xeropthalmia. See text for definitions.
a. Six-month intervals for India; three-month intervals for Indonesia.

A prospective community-based study of all preschool-aged children living in the slums of Hyderabad, India (N = 1,544, based on a population registry), was conducted to estimate the incidence of post-measles corneal disease and its relationship to nutritional status [3]. At baseline, all children were examined by medical officers for signs of vitamin-A deficiency and for clinical signs of lower-respiratory infection, diarrhoea, measles, kwashiorkor, and marasmus; weights were also measured. A diarrhoeal-disease episode was defined as a day with three or more loose stools. This baseline examination was repeated at the next two six-month intervals. After the baseline examination, a surveillance system was established whereby field workers determined morbidity status from weekly home visits.

The method of analysis followed that of the central Java data set [1], but classification as vitamin-A deficient for a six-month interval was restricted to the child's xerophthalmia status at the onset of the interval. For children who were mildly xerophthalmic at the onset of a six-month cycle, the risk of lower-respiratory infection, relative to that for non-xerophthalmic children, was 2 (p = .06), and the relative risk of diarrhoeal disease was close to 3 (table 3). These results were not adjusted for potential covariates.

All incidence episodes during a six-month interval were counted in estimating the relative risk. This cumulative episodic approach to the estimation of relative risk and broader definition of a diarrhoeal case than in the central Java study should increase the relative risk for diarrhoeal disease, assuming that mildly vitamin-A-deficient children would have more episodes of diarrhoeal disease during an interval than non-vitamin-A-deficient children. The rates of diarrhoeal disease among the xerophthalmic and non-xerophthalmic were not, however, significantly different, with a relative risk of 0.90.

In sum, the central Java analyses demonstrated a two-way association between vitamin-A deficiency and diarrhoeal or respiratory infection. The Indian analyses supported an association between mild vitamin-A deficiency and an increased risk of respiratory disease, but they did not demonstrate any association between vitamin-A deficiency and diarrhoeal disease. 95% confidence intervals around each relative risk were not provided in the published reports, it is difficult to determine the extent to which the relative risks overlap.

In both studies, children with corneal xerophthalmia were hospitalized, treated with 200,000 IU of vitamin A, and dropped from the study. Children with severe systemic disease were referred to a health facility. These exclusions for ethical reasons may have reduced the relative risks of xerophthalmia and of infection respectively.

Let us examine the ability to detect an association from the data-collection techniques of these studies. In the central Java study, a child's xerophthalmia status was assessed at an examination every three months, and the diarrhoeal data were based on maternal recall for the month preceding the examination. In the data analysis, this cross-sectionally or retrospectively based classification was considered to be stable across the three-month interval. That is, if a child was diagnosed with mild xerophthalmia at the onset and end of a three-month cycle, then he or she was classified as a xerophthalmia if a mother recalled at least one day during the month preceding the exam in which the child had four or more loose stools, then the child was classified as a diarrhoeal-disease case. However, if a mother with a xerophthalmia child selectively recalled more diarrhoeal episodes than mothers of children without mild xerophthalmia, then this systematic bias could alter the estimate of the relative risk. A crucial question for these investigators is indeed whether the mothers of xerophthalmia children recalled more diarrhoeal disease than mothers of children without xerophthalmia. This analysis would include all children in the study (including those with severe systemic disease who were sent to the hospital) rather than only those with or without mild xerophthalmia at both the onset and end of a three-month period.

In the Indian data analysis, a child's xerophthalmia status at the beginning of a six-month period determined her or his classification for that interval. Given the seasonality of vitamin-A-containing foods in many communities and of vitamin-A deficiency 14]. a healthy child could develop xerophthalmia and vice versa over six months. Thus, children could be misclassified among the healthy and among the xerophthalmics. Such bidirectional misclassification of the exposure variable would bias the estimate of the relative risk of morbidity toward the null value and may have indeed done so [5]. With their weekly surveillance data, the investigators might also be able to analyse the potential association between vitamin-A deficiency and severity and duration of respiratory infection, which would be well worth examining.

An additional effort to clarity the association between vitamin-A deficiency and morbidity requires the collection and analysis of data on potential covariates, such as socio-economic status and nutritional status. For example, poverty may be associated with risk of vitamin-A deficiency and of diarrhoeal disease. Adjustment for socio-economic status may appreciably reduce any association between vitamin-A deficiency and respiratory or diarrhoeal disease [6]. Low weight for a given height may be associated with an acute illness [7] and vitamin-A status. In the central Java study, one might want to analyse those ill with diarrhoeal disease at the examination within levels of weight for height to reduce the potential bias from data collected by maternal recall.

In summary, there is a potentially strong crude association between mild xerophthalmia and an increased risk of a new episode of respiratory disease, but few covariates, if any, have been adjusted in the published reports. The association between vitamin-A deficiency and severity of respiratory disease is unknown. The association between vitamin-A deficiency and the risk and severity of diarrhoeal disease is unclear. The directionality of these associations is also unclear. Since the objective of the above-mentioned studies was to examine either blindness or post-measles corneal ulcers, there is a great need for research on vitamin-A deficiency and morbidity.

Clinical trials

Clinical trials conducted in the United States and Australia are noteworthy because of the consistency of their findings regarding the relationship between vitamin-A status and risk of new respiratory infection [8; 9]. In both trials, the investigators presumed that infants and children at high risk of respiratory infection due to lung injury from either neonatal pulmonary insults from hyaline-membrane disease or from lower-respiratory disease early in childhood would benefit from prophylactic doses of vitamin A, as evidence by reduced incidence of subsequent respiratory disease.

The US trial was a randomized, double-blind, hospital-based study of 40 very low birthweight (<1,300 g) neonates to examine the effect of vitamin-A supplementation on the risk of broncho-pulmonary dysplasia (BPD) [hi. At enrolment, the neonates were clinically and anthropometrically comparable, with mean serum retinal levels of 20 fig per decilitre per group. An intramuscular injection of retinyl palmitate (2,000 IU) or of saline solution was administered to each group every other day for 28 days. During the trial, the vitamin-A-supplemented group experienced increased levels of serum retinal and serum-retinol-binding protein (RBP) following the initial dose of vitamin A, but the placebo group did not show a significant change in the serum retinal and RBP levels (fig. 1). Thus, the change in the serum retinal and RBP levels in the vitamin-A group indicated higher rates of mobilization of vitamin A. No evidence of toxicity from hypervitaminosis-A was identified in the vitamin-A group.

FIG. 1. Plasma concentrations of vitamin A and RBP in infants. Mean values of plasma vitamin A and RBP on postnatal day 4 reflect pre-intervention values and were comparable in the two study groups. In all subsequent determinations, mean values were significantly higher the vitamin-A group. (Source: Ref. 9)

The incidence of BPD and clinical signs associated with it were significantly reduced among the vitamin-A-supplemented group as compared with the placebo group at the end of the trial (45% versus 85%, p < .008) (table 4). The number of infants requiring mechanical ventilation by the end of the trial was significantly lower in the vitamin-A group than in the placebo group (21% versus 55%). The vitamin-A-supplemented group required significantly fewer days of intensive care than the placebo group (63 versus 79, p < .02). However, during the first six months of life, four infants in the vitamin-A group and none in the control group died. Probable causes of death were related either to severe hyaline-membrane disease before enrolment in the trial, which led to BPD in an infant who died on day 13 of the trial, or to postnatal infections acquired two or more months after completion of the trial.

The Australian trial was an offshoot of a pneumo caccal vaccine trial (N = 1,273) [8]. Children one to four years old with a history of 15± days of cough or three separate episodes of respiratory illness during the three months preceding the vitamin-A trial were enrolled (N = 47). Children were randomly allocated to a vitamin-A dose of 3,828 IU or a look- and taste-alike placebo without vitamin A. The treatments were administered three times weekly for six months. Mean serum retinal levels at the onset and completion of the trial were 49 and 50 fig per decilitre respectively, in the two groups (table 5). Mothers kept daily records of signs and symptoms of respiratory illness over the trial period.

Children in the vitamin-A supplemented group who received over 50% of the dosage during the trial were included in the analysis. The vitamin-A-supplemented group had approximately 20% fewer respiratory episodes on average than the placebo group (p = .049) (table 6). Among those with a history of acute or chronic lower-respiratory infection (i.e., prior history of bronchitis, pneumonia, croup, whooping cough, or persistent cough) before the trial, the supplemented group had a 25% lower average rate of respiratory disease episodes than the placebo group (p < .05) (table 7).

Thus, in both trials the vitamin-A-supplemented group experienced a significantly reduced risk of a new episode of respiratory infection compared with the placebo group. These trials were conducted among infants and children who were at high risk of severe respiratory infection and who had different vitamin-A status, neonates with marginal serum vitamin-A levels and children with normal serum vitamin-A levels.

A cautionary note about each trial is in order. In the BPD trial, the increased mortality among the vitamin-A-supplemented group is problematic. An four deaths were attributed to BPD. One possible explanation for this problem focuses on uncontrollable post-trial factors, such as distance from the subject's home to a health-care facility. Although this explanation is conjectural, future research should, as suggested by the authors, maintain surveillance of the diet, morbidity, and vitamin-A status of the study subjects beyond the end of the trial.

The findings of the Australian trial are quite exciting, but because of methodological shortcomings they must be viewed with caution. Notably, the analysis compared the rates of respiratory episodes among the placebo group and those who had a 50% or more compliance with the treatment schedule among the vitamin-A group. Such an analysis destroys the randomization component of the study design. The investigators need to reanalyse their data using all subjects in the vitamin-A group or adjust the current respiratory infection rates of the vitamin-A group to those factors distinguishing the non-compliants from the compliants. Moreover, it is not clear why there was a 20% difference in the rates of respiratory episodes between the vitamin-A and placebo groups but a much smaller, insignificant difference in the mean number of days with specific respiratory symptoms. Perhaps the investigators can describe the missing data about the respiratory-disease episodes that determine the significant difference between the supplemented group and the placebo group. Finally, given the small cell sizes, it may always be uncertain whether these findings are real or due to chance, and, therefore, the trial requires replication.

TABLE 4. Clinical outcome of infants during

	Vitamin-A supplemented	Control	p
Incidence of broncho pulmonary dysplasia
N	9/20	17/20
%	45	85	<.008
Need for mechanical ventilation on study day 28a
N	4/19	11/20
%	21	55	<.029
Ventilatory requirements on study day 28a
FiO2	783 ± 381	895 ± 241	<.040
Ventilator rate	223 ± 530	313 ± 338	NS
peak inspiratory pressure	112 ± 224	231 ± 215	NS
positive end-expiratory pressure	29 ± 43	66 ± 49	<.020
mean airway pressure	59 ± 107	101 ± 76	<.040
oxygenation index	0.63 ± 0.36	0.69 ± 0.15	< 030
Sepsis
episodes per infantb	2.5 ± 1.0	3.1 ± 1.7	NS
airway infectionc
N	4/19	11/20
%	21	55	<.029
Retinopathy of prematurity
N	5/19	12/20	<.034
%	26	60

Source: Ref. 9.

Plus/minus values are mean ±SD. NS: not significant.
a. Area-under-curve values obtained by plotting multiple readings of variable in 24-hour period against time. Patient 1, who died on postnatal day 13 is excluded from this analysis.
b. Clinically suspected sepsis with or without confirmation by microbiologic culture resulting in initiation of antimicrobial therapy.
c. Confirmed by positive microbiologic cultures of airway secretions.

Table 5. Mean plasma vitamin-A concentrations in supplemented and unsupplemented groups

Retinol (1g 100ml)
Initial			Final
Mean	SE M	Mean	SE M	N
Placebo	48.9	2.0	49.9	1.6	43
Supplement	50.5	1.8	50.2	1.7	47

Source: Ref. 8.

In sum, compared with the placebo group, the vitamin-A-supplemented group had a reduced incidence of new episodes of (BPD) respiratory disease. The Australian trial data were stratified by history of allergy and of lower-respiratory infection, but no other adjustments for potential covariates were made. These trials were conducted among infants and children at high risk of respiratory disease, but this effect has not been demonstrated among pre-school-aged children who are not at risk of severe respiratory infections.

Vitamin-A deficiency and measles complications

Now let us turn to the potential relationship between vitamin-A deficiency and measles complications, including respiratory and diarhoeal disease, corneal ulcers, and mortality. Measles is a highly contagious disease that infects all susceptibles when exposed. Infection with this virus is characterized by impaired host immunity, which may increase the risk of complications among the already malnourished [10; 11]. Measles reduces energy intake, utilization, and absorption and damages the epithelial cells of the respiratory and gastrointestinal tracts [12; 13]. All these factors may act individually or in combination to increase the risk of complications.

TABLE 6. Mean respiratory symptoms in vitamin-A-supplemented and placebo groups

	Placebo (N=54)	Supplement (N= 53)	Difference (%)	Significance (p)a
	Mean SE M	Mean SE M
Episodes of all symptoms	8.0 0.57	6.5 0.45	-19	.049
Days of all symptoms	72.7 5.7	72.7 8.7	0	NS
Nose (days)	62.5 5.2	54.7 7.4	-12	NS
Cough (days)	28.3 3.6	32.2 5.3	-12	NS
Chest (days)	15.1 3.3	13.7 5.0	-9	NS

Source: Ref. 8.
a. Student's t-test. NS: not significant.

TABLE 7. Percentage differences between supplemented- (S) and placebo-group (P) means (P - S) stratified by allergy and lowerrespiratory-illness (LRI) history

	History of allergy		History of LRI		Total population
	No	Yes	No	Yes
N	63	44	39	68	107
Episodes of all symptoms	-11 (NS)	-25 (NS)	0 (NS)	-25(P < .05)	- 19 (P < .05)
Days of all symptoms	17 (NS)	-16 (NS)	4 (NS)	-1 (NS)	0

Source: Ref. 8.

Vitamin A has an important role in cell reproduction and differentiation of the respiratory and gastrointestinal tracts, mucosa of other organs, immune system, and conjunctiva/cornea of the eye [14-21]. Given the physiological functions of vitamin A, its deficiency has the potential to act synergistically with measles infection in the incidence of measles complications. Indeed, measles and vitamin-A deficiency have similar complications, such as diarrhoea, acute respiratory disease, and xerophthalmia [20; 22-27].

There are two recent publications on this subject. In the 15-month community-based study of post-measles complications and nutritional status in a slum area of Hyderabad, India, that was discussed earlier [3], the measles attack rate among pre-school-aged children was 23% (N = 318/1,544) [28]. Among the measles cases, the incidence rate for bronchopneumonia was 34%, for diarrhoea 37%, and for corneal lesions 3% (table 8). Children between one and two years of age suffered from the highest rates of measles and measles complications.

TABLE 8. Incidence of complications during measles

Age (years)	No. of measles cases	With broncho- pneumonia	With diarrhoea	With corneal lesions
<1	69	24	29	3
1+	105	40	45	4
2+	62	21	22	0
3+	47	16	11	0
4+	35	8	11	3
0-4+	318	109	118	10
(100%)	(34 3%)	(37.1%)	(3 1%)

Source: Ref. 28.

The mean serum retinal levels of the Indian children were always below 20 fig per decilitre regardless of measles status (table 9). During measles, the mean serum retinal levels of children with and without secondary infections or corneal lesions were not significantly different (table 10). During fever, serum retinal levels are spuriously lowered, and in a small subsample of 32 measles cases the serum retinal levels were lower during the acute phase than during the pre- and post-measles period (table 11). Malnourished measles cases (based on Gomez classification) had significantly lower mean serum retinol and albumin levels than their better nourished counter-parts (table 12).

In a Tanzanian randomized trial of hospitalized measles cases who received either a high dose of vitamin A (200,000 IU) on two consecutive days (N=88) or standard therapy without vitamin a (N=92), the case fatality rate during the month following measles was 7% (N=6/88) in the vitamin-A-supplemented group (p=.13) (table 13) [29]. A significant difference was observed among children under two years old, with a 2 % versus 17% case fatality rate (p<.05). Additionally, marasmic children had a fourfold higher case fatality rate than better nourished children regardless of treatment allocation. These findings should be considered suggestive because the total number of deaths (N=18) was small and trial was not double-blind inasmuch as the paedriatricians knew each subject’s treatment group.

TABLE 9. Biochemical parameters (cross-sectional data)

Serum levels
N		Albumin (g/dL)	Retinol (µg/dL)	RBp (mg/dL)
Control (C)	117	3.6 ± 0.03	17.9 ± 0.81	2.5 ± 0.06
Measles during infection
(Ma)	153	3.4 ± 0.03	11.5 ± 0.44	2.1 ± 0.07
after recovery (M2)	108	3.5 ± 0.05	19.8 ± 0.69	2.5 ± 0.06

Source: Ref. 28. Values are mean ± SE
Statistical significance -
C vs. M₁ p < .001 for albumin for retinol and for RBP.
M₁ vs. M₂: NS for albumin; p< .001 for RBP.

TABLE 10. Biochemical parameters (longitudinal data on TABLE 13. Mortality of children admitted with measles 32 children)

	Serum levels
	Albumin (g/dL)	Retinol (µg/dL)	RBP (mg/dL)
Premeasles (PM)	3.6 ± 0.07	16.5 ± 1.75	2.4 ± 0.14
Measles ( M, )	3.4 ± 0.08	11.1 ± 1.1	2.2 ± 0.17
Postmeasles (M2)	3.7 ± 0.07	19.2 ± 1.68	2.3 ± 0.15

Source: Ref. 28.
Statistical significance -
PM vs. M₁: p<.05 for albumin; p< .02 for retinal; NS for RBP.
M₁ vs. M₂: p < .01 for albumin, p < .001 for retinol: NS for RBP

TABLE 11. Serum vitamin-A levels in relation to measles and corneal lesions

Corneal changes in measles	N	Albumin (g/dL)	Retinol (µg/dL)
No change	47	3.3 ± 0.09	13.7 ± 1.37
Coarse keratitis	19	3.2 ± 0.09	10.8 ± 1.08
Fine keratitis	6	3.2 ± 0.14	11.6 ± 1.39
Corneal xerosis	20	3.3 ± 0.07	11.5 ± 1.63

Source: Ref. 28.

TABLE 12. Biochemical parameters in measles according to nutritional status

Nutrition Grade	No. of children	Albumin (g/dL)	Retinol (µg/dL)	RBP (mg/dL)
Normal+
Grade I	58	3.4 ± 0.05	12.5 ± 0.80	2.0 ± 0.80
Grade II	74	3.4 ± 0.05	11.3 ± 0.60	2.2 ± 0.09
Grade III	21	3.2 ± 0.07a	8.3 ±0.75b	2.2 ± 0.15

Source: Ref. 28.
a. p < .05 compared with Normal + grade I.
b. p < .02 compared with Normal + grade I.

TABLE 13. Mortality of children admitted with measles

Age (months)	Children admitted		Children who died
	Given vitamin A	Controls	Given vitamin A	Controls
<9	14	9	0	2(22)
9 - 11	12	10	0	2(20)
12-23	20	23	1(5)	3(13)
24-35	11	16	3(27)	2(13)
36-47	11	13	1(9)	1(8)
48- 59	8	6	1(13)	0
³	12	15	0	2(13)
Total	88	92	6(7)	12(13)

Source: Ref. 29.
Principle data are numbers of children. Figures in parentheses are percentages.

TABLE 14. Measles complications and associated mortality

Complication	Children with complications		Children who died
	Given vitamin A	Controls	Given vitamin A	Controls
Pneumonia	38 (43)	47 (51)	3 (8)	7 (15)
Otitis media	19 (22)	20 (22)	1 (5)	3 (15)
Group or laryngo tracheobronchitis	8 (9)	13 (14)	1 (50)	4 (31)
Dysentery	2 (2)	6 (7)	1 (4)	3 (50)
Haemorrhagic rash	28 (32)	34 (37)	1 (11)	4 (12)
Oral candidiasis	9 (10)	5 (5)		1 (20)

Source: Ref. 29.
Principle data are numbers of children. Figures in parentheses are percentages.

Based on the two measles studies presented above, vitamin-A deficiency and measles complications do co-occur but are not necessarily associated. Nevertheless, the pathophysiology is sufficiently similar in measles and vitamin-A deficiency to suggest the need for future research in this area.

The evidence from the hospital-based trial leads us back to the potential association between vitamin-A deficiency and respiratory disease inasmuch as respiratory-specific mortalities were reduced among the vitamin-A-supplemented versus the control group (table 14). Given the findings of respiratory-disease-specific mortality differences in the Tanzanian trial, a follow-up study might be designed as a randomized double-blind trial of vitamin-A supplementation (versus a placebo) administered to measles and non-measles respiratory-disease cases to compare their risk of mortality.

A curious feature of the Tanzanian trial is the absence of any diarrhoeal-disease deaths. In the Indian study [28|, 34% of the measles cases suffered from diarrhoeal-disease complications during the acute stage of measles, and 76% suffered from diarrhoeal disease during the six months following measles. Thus, the clear absence of any diarrhoeal deaths in the Tanzanian trial is noteworthy.

Before leaving the subject of vitamin-A deficiency and measles complications, I would like to discuss current World Health Organization recommendations 130] briefly. The WHO and the United Nations Children's Fund recommend that a high-potency preparation of 100,000 and 200,000 IU of vitamin A be administered to measles cases under and above one year old respectively. They state that this therapeutic regimen should be followed in communities with measles fatality rates of 1% or higher or in communities with recognized vitamin-A deficiency. This recommendation is based on the above-mentioned hospital-based trial in Tanzania, but the dosages differ. Moreover, this recommendation is presented for a broader range of communities than can be extrapolated from the trial: vitamin-A distribution to measles cases is recommended for any community with a measles-case fatality rate of 1% or more regardless of its vitamin-A status.

Before such a recommendation is implemented, several studies might be conducted, including a trial of vitamin-A supplementation (versus a placebo) before the measles season to examine the risk of the incidence and duration of measles complications. Another trial might examine the impact of a high-potency preparation of vitamin A (versus a placebo) administered to non-hospitalized measles cases during the acute stage on the incidence and duration of complications. These trials would address the preventive effect of the administration of vitamin A compared with that of a placebo prior to and during the measles season.

Summary and research recommendations

Let me briefly summarize this review and discuss several issues regarding future research. First, there is a potentially strong association between vitamin-A status and the risk of respiratory infection. Second, it is more difficult to state the potential for the association between vitamin-A deficiency and diarrhoeal disease based on the techniques of morbidity assessment or the analytic approach to data taken in published articles. It is noteworthy that the studies presented were not designed to examine the association between vitamin-A deficiency and morbidity. Third, vitamin-A deficiency and measles complications co-occur, and indeed, vitamin-A supplementation during measles may reduce respiratory-specific causes of mortality. These statements refer primarily to crude associations that require adjustment for potential covariates in future research.

One cannot address future research in vitamin-A deficiency without examining methods of vitamin-A assessment and detection of morbidity. Essentially, researchers must be able to determine subclinical and clinical vitamin-A deficiency in order (a) to compute an unbiased estimate of the risk of morbidity among these two groups in comparison with those who have adequate vitamin-A status and (b) to examine the potential threshold effect of vitamin-A status on morbidity. Various methods of vitamin-A assessment exist, but ideally they should be evaluated for their field applicability [31; 321, their sensitivity and specificity across the spectrum of vitamin-A deficiency, and their reproducibility before research on vitamin-A deficiency and morbidity is conducted.

Another complicating issue in vitamin-A assessment is determining the vitamin-A status of febrile children, notably children with acute infections, because fever spuriously lowers serum retinal levels. This issue needs to be addressed in virtually all vitamin-A and morbidity studies that assess the vitamin-A status at the time of diagnosis of an infection. One plausible method of correcting for the effect of fever on serum retinal levels is to measure the levels of serum acute-phase reactant protein, which is inversely associated with serum retinal levels under stressful conditions (such as after surgery). Thus, the changes in C-reactive protein levels [33] can be used to adjust the serum retinal levels to pre-infection status.

The ability to detect an association between vitamin-A deficiency and diarrhoeal and respiratory infections, as well as the direction of that association, is contingent on the quality of morbidity data collection. The information required for diagnosis and determination of the severity of infection includes standardized clinical validation and, preferably, microbiologic analysis. In a proposed University of Gadjah Mada and Johns Hopkins University vitamin-A and morbidity field trial [34], my colleagues and I are developing a morbidity surveillance system of twice-weekly home contact with the child's caretaker in order to identify symptoms and signs of infection. Within 24 hours of the identification of a potentially ill child, a physician will *sit the home to validate the diagnosis clinically and take a specimen for microbiologic analysis. With this information, we will be able to distinguish single from multiple episodes, the duration of each episode, and acute from chronic episodes. With such data one can examine whether vitamin-A deficiency increases the risk of a new episode and/or the severity of an infection and, indeed, the association between vitamin-A deficiency and etiologic-specific agents of diarrhoeal and/or respiratory disease.

If future studies of vitamin A and morbidity are designed as clinical of field trials, then some attempt should be made to validate the proper dosage of vitamin A to be administered in the trials. Two hundred thousand IU of vitamin A is the high-potency preparation of vitamin A that will be administered in all the ongoing mortality trials and the proposed morbidity trials. This dosage is based on one study of Brazilian children under 10 years old who had a relative-dose-response test at baseline, followed by the administration of a dose of 200,000 IU of vitamin A. At 30, 120, and 180 days after the dosing, the relative-dose-response test was repeated to determine the time interval until return to the baseline serum retinal levels 1351. The impact of dosages lower than 200,000 IU on the risk of morbidity or mortality has not been examined, but the ethical objectives of current field trials should be the administration of the lowest dosage of vitamin A that potentially reduces the risk of morbidity.

All research on vitamin A and morbidity should be conducted in communities with evidence of clinical and/or subclinical vitamin-A deficiency to ensure that there will be beneficial effects of a trial by treating children with xerophthalmia. Thus, recent data on vitamin-A deficiency rates within the past five years are required before the onset of the trial.

Finally, covariates that may potentially influence the association between vitamin A and morbidity include season; dietary intake of vitamin A, protein, and fats; anthropometric status, including weight and height; intestinal parasites that may reduce the ability to absorb vitamin A; socio-economic status; access to and utilization of health care; and child's age and sex. Information about these variables should be collected during a study, and the variables should be examined as potential interaction terms, effect modifiers, and/or confounding variables with respect to the association between vitamin-A deficiency and morbidity.

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21. Underwood BA. Vitamin A in animal and human nutrition. In: Sporn MB, Roberts AB, Goodman DS, eds. The retinoids. Orlando, Fla, USA: Academic Press, 1984:vol.1 :281-392.
22. Bhaskaram P. Reddy V, Raj S. Bhatnagar RC. Effect of measles on the nutritional status of preschool children. J Trop Med Hyg 1984;8:21-25.
23. Blackfan KD, Wolbach SB. Vitamin A deficiency in infants: clinical and pathological study. J Pediatr 1933; 33:679-706.
24. Koster FT, Curlin GC, Aziz KMA, Haque A. Synergistic impact of measles and diarrhoea on nutrition and mortality in Bangladesh. Bull WHO 1981;59:901-08.
25. Pongrithsukda V, Phonboon K, Manunpichu K. Measles-associated diarrhoea in northeastern Thailand. Southeast Asian J Trop Med Public Health 1986;17:4347.
26. Sanford-Smith JH, Whittle HC. Corneal ulceration following measles in Nigerian children. Br J Ophthamol 1979;63:720-24.
27. Shahid NS, Caluquin P. Shaikh K, Zimicki S. Long-term complication of measles in rural Bangladesh. J Trop Med Hyg 1983;86:77-80.
28. Reddy V, Bhaskaram P. Raghuramulu N. et al. Relationship between measles, malnutrition, and blindness: a prospective study in Indian children. Am J Clin Nutr 1986;44:924-30.
29. Barclay AJ, Foster A, Sommer A. Vitamin A supplements and mortality related to measles: a randomized clinical trial. Br Med J 1987;294:294-96.
30. Vitamin A for measles Joint WHO/UNICEF statement. Wkly Epidem Rec 1987;19:133-34.
31. Underwood BA. Effect of protein quantity and quality on plasma response to an oral dose of vitamin A as an indicator of hepatic vitamin A reserves in rats. J Nutr 1980;110:1635-40.
32. Wittpenn JR, Tseng SCG, Sommer A. Detection of early xerophthalmia by impression cytology. Arch Ophthalmol 1986;104:237-39.
33. Labadarios D, Brink PA, Weich FH, et al. Plasma vitamin A, E, C and B6 levels in myocardial infarction. S Afr Med J 1987;71:561-63.
34. Forman MR, Brown KH, Black RE, Sack RB, Steinoff M. Proposal to assess the impact of vitamin A supplementation on the reduction of the incidence and duration of episodes of morbidity among children aged 6-60 months in Indonesia. Presented at the National Academy of Sciences, 17 Aug 1986. Institute of International Programs and Department of International Health, School of Hygiene and Public Health, Johns Hopkins University, in collaboration with the University of Gadjah Mada, Yogyakarta, Indonesia, 1988.
35. Flores H, Campos F, Araujo CRC, Underwood BA. Assessment of marginal vitamin A deficiency in Brazilian children using the relative dose response procedure. Am J Clin Nutr 1984;40:1281-89.

Ethical issues related to nutrition field trials

Joan P. Porter

This paper reviews several fundamental ethical principles, provisions of the US federal regulations for the protection of human subjects, and past deliberations of the Subcommittee on Vitamin A Deficiency Prevention and Control regarding ethical concerns in vitamin-A studies. The fundamental ethical principles were set forth by the National Commission for the Protection of Human Subjects of Biomedical and Behavioral Research in its Belmont Report |l]. These principles were the basis for the regulations of the Department of Health and Human Services (DHHS) for the "Protection of Human Subjects" [2], and they guide the design, review, and conduct of any research involving human subjects - they are the foundation for our rules and norms.

Ethical principles

The first ethical principle is respect for persons. Two corollaries of this principle are that individuals should be treated as autonomous agents and that persons with diminished autonomy are entitled to protection. Kant stated the principle in these words: "So act as to treat humanity, whether in thine own person or in that of any other, in every case as an end withal, never as a means only`' [3]. Obtaining informed consent is an important activity in research that derives, in part, from this principle.

The second principle is beneficence. Persons are treated in an ethical way by making efforts to serve their well-being. Beneficent actions involve two rules: "do not harm"; maximize possible benefit and minimize possible harms. Claude Bernard indicated that one should not injure even one person involved in research regardless of the benefit that might come to others 13]. This is not always an easy principle to app ly, because avoiding what is harmful requires learning what is harmful, and that sometimes means exposing people to risks of harm. Also, researchers have to act to benefit their subjects based on their best judgement - and at times there is no ready consensus or scientific information about what is in the best interest of human beings. These imperatives, then, require us to weigh possible risks and possible benefits and to determine what is too great a risk in pursuit of a possible benefit. Research designers and groups who review research seek to minimize the risks and to maximize the benefits by using procedures, processes, and designs that clearly weight the benefits side of the scale - for the individuals involved and also for individuals to follow and for society in general.

Some ethicists who have considered beneficence have said there are obligations that derive from this principle. In Frankena's schema [cited in ref. 3, p. ill], for example, these are, in order of strength: (l) One ought not to inflict evil or harm. (2) One ought to prevent evil or harm. (3) One ought to remove evil. (4) One ought to do or promote good. I will return to the balancing of risks and benefits below.

The third principle is justice. Justice requires that we treat persons fairly and that we give each person what he or she is due. The National Commission [1] was concerned, in large part, with "distributive" justice, which involves the distribution of scarce benefits when there is competition for them. It was also concerned with the distribution of burdens, particularly with regard to imposing burdens on fewer than all members of a class of persons. lust distribution of burdens and benefits is an important concept underlying the selection of research subjects. As the National Commission notes, researchers have to decide who should receive the benefits and who should bear the burdens. The selection of subjects must be carefully reviewed to determine whether some classes are being systematically selected primarily because of their easy availability or manipulability. If the research pays off, one concept of justice requires that those who are disadvantaged have access to the benefits of research and that those who have borne the burdens be considered with high priority in distributing the benefits [l].

In writing about research and treatment of acquired immunodeficiency syndrome (AIDS), Leroy Walters [4] of the Joseph and Rose Kennedy Institute of Ethics has suggested a still nebulous, fourth ethical principle: "community," or "mutuality," or "solidarity." This principle acknowledges that, in view of the complexities of major health epidemics or problems, we must include this value with others to guide actions. Some of the vitamin-A studies in question here must accommodate the importance of local authority and of community reassurance and participation in decision making. These values appear to be related to Dr. Walters's emergent principle.

Risks and benefits

Risks and benefits can be physical, psychological, social, and economic. In this regard, we tend to think of the vitamin-A studies as trade-offs of physical risks and benefits, but the culture of the research subjects may sometimes create subtle benefits or risks - community pressure about participating or not participating in a study or risks of excessive expectation. Possible psychological risks might derive from one's having improved health by virtue of receiving an intervention or accompanying medical attention and then having that benefit withdrawn, sometimes rather rapidly, after the completion of a trial. The mere inconvenience of an intrusion into one's daily activities may also be a risk.

In the best of situations, those who are designing the research would provide quantitative estimates of the probability and magnitude of risks and benefits based on empirical data, but that is not an easy task. There may not be agreement, for example, on how to weigh a risk or benefit, or agreement on the relevance or accuracy of previous findings.

Several points about benefits should be considered when vitamin-A studies are contemplated. First, anticipated benefits really have to be weighed in terms of expected duration. Also, research designers must consider what happens if the benefit of an experimental health intervention is provided in a community that would not otherwise have access to it. Is there any possibility of continuation through other governmental or private support once an efficacious research intervention ceases?

Second, in areas of the world where individuals have no access to basic health care, one sometimes hears the argument that persons in the control group of a randomized trial, who receive no intervention or who receive a placebo, are "no worse off" for the re search. They did not have access to a vitamin or other nutrient before the trials, so why should we be concerned if they have none now in the trial? Are the risks any greater, considering probability and magnitude, than those they ordinarily encounter in daily life [2]? Some may argue that this rationale seems to contradict the obligation to maximize benefits - especially if there are relatively basic medical interventions basic medical interventions that can be provided to study subjects.

Third, there exists a dilemma if agreement is lacking on what works and what does not or on what previous research means or requires us to do to avoid harm and to promote benefit. Widespread application of tentative or unproven interventions is not ethical - it prevents us from finding the best treatment, raises hopes inappropriately, and exposes those who receive the unproven intervention to unknown risks. Further, unsound health interventions waste resources in a world where they are scarce.

Fourth, the concept of benefit is also closely linked to selection of subjects, as noted above. Those who stand to gain the most from the research results are those who might first be asked to assume the risks. In discussing maximization of benefits, Robert Levine [3] of Yale University suggests that ethical codes and regulations forcefully prohibit causing death or injury, but obligations to promote good are based on good scientific design and good balance of harms and benefits. If the benefit of promoting health is based on the obligation to avoid harm, then every subject - even those in a control group - should have the best proven diagnostic and therapeutic method. Witholding an effective therapy for a disease that if untreated may produce death or disability is not acceptable according to Levine [3, P 45].

A corollary to justifying risks in terms of benefits is the obligation to minimize risks. Sometimes minimization takes the form of eliminating non-essential procedures, such as drawing extra blood. Another approach is monitoring, through data and safety monitoring boards, in blinded trials to detect unanticipated statistical trends that reveal problems or results that are so dramatic that justification to continue the controlled trial is unwarranted. Setting clear end points and building consensus on the meaning of the data flow from the monitoring concept.

Prescreening is another way to minimize risk. For example, in the vitamin-A studies, children with clear signs of ophthalmological symptoms were not entered into the trials or were withrawn from the test groups and treated. In selecting subjects, research designers should consider involving the least vulnerable, least at-risk persons to obtain the data needed. Some may say that this takes the form of involving persons with marginal deficiencies or only mild illnesses rather than those at later stages of deprivation or illness, if possible. Other things being equal, one looks for the least vulnerable representatives of populations as subjects.

Some of the studies the subcommittee reviewed in 19S6 involved the randomized clinical trial, in which one group receives the intervention and a control group receives a placebo or nothing [5]. Many ethical problems are peculiar to this type of study design. Some researchers believe that we have relied on randomized clinical trials too much. D. L. Sackett [cited in ref. 3, p. 136] maintains that the objectives of clinical trials are validity, generalizability, and efficiency - the first objective, validity, being the mandatory one. Sackett believes that problems arise when the three objectives are out of balance or given the wrong priority. For example, efficiency might require that high-risk persons be enrolled so that dramatic results can be achieved, but validity and generalizability may be compromised.

Use of historical controls is one alternative to randomized clinical trials. But, in the face of many confounding factors, this design is often criticized. Richard Feachem has suggested that it is unethical to follow prospectively children with any signs or symptoms of vitamin-A deficiency without providing full vitamin-A therapy. He also suggested use of the case-control method in diarrhoeal and vitamin-A studies as an alternative to randomized clinical trials [6, p. 13].

US federal regulations

The ethical principles that have been set forth are not always easy to apply. Nor is it always evident how to apply them. The DHHS regulations for the protection of human subjects [2l provide some rules and processes for application of the principles. Two processes required by the regulations provide a means to put the principles into practice: use of an institutional review board (IRB) and obtaining informed consent. Although some of ethical codes, such as those of Helsinki or the Council of International Organizations of Medical Societies of the World Health Organization, recommend general courses of action for the conduct of ethical research, the DHHS regulations are more explicit and precribe procedures.

(Not addressed here is subpart D of the regulations, "Additional Protections for Children Involved as Subjects in Research." Note that the regulations provide several additional risk/benefit categories for an IRB to examine. For example, if, in a research protocol intended for support, the risks are relatively high and the knowledge to be gained and benefits are quite important but far removed from the children who are subjects, the Secretary of Health and Human Services would convene a second review to consider the research and make recommendations about whether it can go forward.)

Institutional review boards

The regulations call for a local committee of specific composition, an institutional review beard, with sufficient authority and an independent perspective to assess the balance of the possible risks and possible benefits of research. The IRB assesses the minimization of risks, the adequacy of the informed-consent process, and protection of vulnerable subjects. Along with research experts, the IRB must include persons unaffiliated with the institution sponsoring the research, persons who can represent community attitudes and values, and persons who are not scientists [2l. Although it is important to involve government officials in the planning of field studies, sometimes the perspective of those with other than political agendas can help sort out what are acceptable risks and benefits.

In negotiating assurances of compliance with the regulations for the protection of human subjects for research that is sponsored by a domestic institution in a foreign country, the Office for Protection from Research Risks, with few exceptions, asks for at least two IRB reviews - one by the IRB in the domestic institution and one in the country where the research is to be conducted. Local review, i.e., in the community where the research will take place, is sought. Whereas most IRBs in the United States are attached to academic or research organizations, there are many variations abroad. Quite often an existing government review committee, supplemented to meet the requirements of the regulations, is utilized. Because the governments often do not do research, reviews can be complicated by other goals. In most of the trials, the national governments are involved at some point, and they must be for the success of the effort and for ensuring continued commitment if the results of the research are favourable.

Obtaining informed consent

The other process required by the regulations is obtaining informed consent. The basic elements of informed consent include considerations a reasonable person would want to know. The informed-consent process respects the value of autonomy of an individual. In this process, persons must be told (a) that the intervention is research, (b) what alternative treatments there are, if any, and (c) the foreseeable risks and foreseeable benefits to themselves and to others from their participation as subjects. They are informed about the extent of confidentiality and, if the research is of more than minimal risk, of any availability of compensation in the event of an injury. They are told that their participation is voluntary, that they may withdraw at any time, and that, if they decide not to participate in the research, they will not be denied any benefits to which they might otherwise be entitled. They are also given the name of someone of whom they may ask additional questions [2].

Informed consent, verbal or written, must be obtained; but, if it is to be meaningful, information must be explained, and it is no easy task to explain alternative methods, long-term risks and discomforts, and possible benefits, particularly to potential subjects in developing countries [7].

To hand out consent forms to illiterate people is not sufficient. Also, in some areas, signing any papers is considered an act of self-incrimination or makes possible subject quite uneasy. One might also need to seek consent from the traditional head of an area, a parent, or the chief teacher for schoolchildren. Husbands must also consent for their wives in some areas

In the United States, we place a high value on autonomy and individual rights. In other cultures, this value is modulated somewhat by values of community solidarity and community authority. In such cultures, it is important to convince local tribal and village elders and religious leaders of the acceptability of the research to be done. This requires more lead time to prepare for a study, but it helps to ensure a high degree of participation and compliance. Obtaining the local leader's consent is necessary, but is not sufficient to guarantee participation. Dr. Keith West of the Johns Hopkins Medical Institution cautions that sensitivity to superstitions, local norms, local behavior - indicators that tell a researcher whether someone is consenting or refusing - is essential (personal communication, 1988). De Maar et al. [7] and others writing about the management of clinical trials in developing countries have advised that constituting permanent national or international advisory committees to provide broad support can be helpful (e.g., scientific advice and data monitoring), but they can be costly. Also, the co-operation and understanding of local health dignitaries and the traditional medicine man or the local dispenser should be sought. Their dissatisfaction could jeopardize a study [7].

In developing countries in which field trials are to be conducted, researchers and IRBs need to consider, then, the constraints on obtaining permission to conduct trials and on obtaining informed consent. E. Ekamen [8] of Nigeria, in discussing methodological constraints and limitations in developing countries, cited illiteracy as the major drawback to the conduct of research. Populations are often ill-informed and have little understanding of the value and objectives of research projects; they do not participate unless some clear benefit is offered. Language barriers should not be underestimated; sometimes there are no local concepts for the technical terms involved in research. Concepts of time and causality are culturally defined. Placebo-controlled trials and blinded and double-blinded studies are not well understood [9]. Also, it should be remembered that selecting persons as potential subjects who are in schools or other institutions in developing countries may lead to a biased sample of the general population.

Previous subcommittee deliberations

The deliberations of the subcommittee in August 1986, as reported in Vitamin A Supplementation: Methodologies for Field Trials [5], identified the following problems:

• the lack of data about the effects of vitamin A on mortality among people with marginal vitamin-A status, i.e. without clinical signs;
• inconclusive animal data concerning the relationship of vitamin A and resistance to infection;
• lack of consensus on the meaning of Sommer's [10] clinical trial in Indonesia, and the lack of consensus on the need for additional controlled trials to demonstrate with scientific rigour the effects of vitamin A on morbidity.

There were minority opinions among the subcommittee. Some, for example, noted that persons with marginal vitamin-A status are at increased risk of developing severe deficiency. Their risk remains if they are in the control group receiving a placebo. Children who will eventually become xerophthalmic because of vitamin-A deficiency are already compromised, but the ways to measure and diagnose this are not so direct. Because some subcommittee members do not consider vitamin A an "experimental agent," they urged studies without placebo groups in areas of high morbidity and xerophthalmia. Others were concerned that high risks were borne by the control population, whereas benefits would be universal.

A suggestion was that an alternative to randomized clinical trials that would shift or minimize risks more appropriately might be retrospective case control studies of mortality based on who accepts and who refuses vitamin-A supplements. Other possibilities suggested were time-staggered introduction of capsules and other services into planned vitamin-A health care delivery and intensive vitamin-A distribution to selected populations, and regular distribution of government supplements to other populations.

Ethical safeguards considered by the subcommittee included the following:

• careful assessment of risk based on the data available;
• identification of benefits that could accrue to both participating and control groups in the trial;
• building into studies US and foreign reviews for the protection of human subjects;
• establishing data and safety monitoring boards; - identification of the need for informed consent;
• extension of the benefits of the research to the control group as soon possible after the trial.

It appears that tensions surround the questions of how much we already know and of the extent to which subcommittee members agree on the validity and generalizability of the research data about vitamin-A studies. Ethical deliberations are not undertaken within a neat framework. There is always some degree of conflict about the nature and weights of values, benefits, and risks, about the primacy of principles, and about interpretation of previous studies. There are also conflicts about deciding on research priorities and about balancing research versus other immediate health treatment necessities in the face of scarce resources.

The subcommittee needs to address these points in considering future studies. Although there are no easy answers, this paper should help to refresh memories about past discussions and to guide future

References

1. National Commission for the Protection of Human Subjects of Biomedical and Behavioral Research. The Belmont report: ethical principles and guidelines for the protection of human subjects of research. US Department of Health, Education and Welfare. DHEW publication no. (05)78~012. Washington, D.C.: US Government Printing Office, 1978.
2. US Department of Health and Human Services (DHHS). Protection of human subjects. Title 45, Code of Federal Regulations, part 46. Office for Protection from Research Risks. OPPR reports. Washington, D.C.: National Institutes of Health, Public Health Service, 1983.
3. Levine R1. Ethics and regulation of clinical research. 2nd ed. Baltimore, Md, USA: Urban & Schwarzenberg, 1981.
4. Walters L. Ethical issues in the prevention and treatment of HIV infection and AIDS. Science 1988;239:597603.
5. National Research Council. Vitamin A supplementation: methodologies for field trials. Subcommittee on Vitamin A Deficiency Prevention and Control, Committee on International Nutrition Programs, Food and Nutrition Board, Commission on Life Sciences. Washington, D.C.: National Academy Press, 1987.
6. Feachem RG. Vitamin A deficiency and diarrhoea: a review of interrelationships and their implications for the control of xerophthalmia and diarrhoea. Trop Dis Bull 1987;84:R1-R16.
7. De Maar EWJ, Chaudhury RR, Ekue JMK, Granata F. Walker AN. Management of clinical trials in developing countries. J Int Med Res 1983;11:1-5.
8. Ekamen EE. Field epidemiology: methodological constraints and limitations in the developing world. Public Health 1985;99:33-36.
9. Halsey N. Responsibilities in international AIDS research. Regional workshop on the protection of human subjects: new trends and issues. 12-13 May 1988. Sponsored by the University of Maryland Graduate School, the National Institutes of Health, Office for Protection from Research Risks, and the Food and Drug Administration, Public Health Service. Baltimore, Md, USA: Department of Health and Human Services, 1988.
10. Sommer A, Tarwotjo 1, Djunaedi E, et al. Impact of vitamin A supplementation on childhood mortality. Lancet 1986;2:1169-73.

Commentary: Underpinning vitamin-A deficiency prevention and control programmes

Barbara A. Underwood

If you give a hungry man a fish, he is fed for one day but is dependent upon you for continued sustenance. If you teach a hungry man to fish, he is independent for life.

The analogy between this well-known saying and the approaches to the prevention and control of vitamin-A deficiency is obvious: providing children with high-dose capsules of vitamin A saves many from developing clinical symptoms and perhaps reduces mortality and morbidity, as long as the dose can be delivered repeatedly at specified intervals. If the system fails or the individual child is not reached, the problem recurs. Approaches to prevention that foster practical solutions attainable through better utilization of available food and other resources are more difficult to implement and take longer to bring about the needed behavioural changes in child-rearing practices. But they can be permanent and address health and nutrition issues that commonly coexist with vitamin-A deficiency.

Most vitamin-A intervention programmes recognize these facts and include an "educational" component. In practice, however, the educational component takes a back seat to efforts required for the delivery and monitoring of the high-dose capsule. The personnel responsible for capsule delivery frequently inform recipients of what the capsule is for and of foods they should eat that contain the vitamin, but fail to communicate the message in a locally appropriate, meaningful way that changes behaviours: such communication may be perceived as taking too much time. This fact is illustrated by the evaluation report of the Bangladesh vitamin-A distribution programme described in an earlier issue of the Food and Nutrition Bulletin [1].

Clearly there is need to rethink strategies for vitamin-A-deficiency prevention and control. The high-dose medical approach is appropriate under circumstances where a public health problem exists and alternatives are not feasible, e.g. where water, transportation, and food-storage facilities are in short supply or non-existent. Often, however, these circumstances are regionally clustered and not applicable to an entire country. But even under these circumstances, strategies that combine the short-term medical approach with programmes addressing underlying conditions that contribute to high rates of infections - e.g. programmer to improve personal and environmental sanitation and increase immunization coverage - can have beneficial spin-off effects on the vitamin-A deficiency problem. As the evaluation of the Bangladesh programme by Darnton-Hill et al. [1] illustrates, the efficacy of the medical model is limited by the inefficient delivery system. There is no doubt that the programme has saved the sight and lives of many Bengali children, but, as the authors note, it has not reduced the overall prevalence of the problem - even after 14 years. In addition, the struggle to improve the delivery system and its monitoring is consuming much of the national human and economic resource pool.

During the 14 years of the Bangladesh programme, some evidence indicates that diets not only have not improved nutritionally with respect to vitamin A but have deteriorated, and that little change has occurred in personal and environmental health practices. After 23 rounds of vitamin-A-capsule distribution, limited knowledge about the programme exists: 34%-60% of mothers did not know what the capsule was for, 15%21% had not seen the educational materials, and 51%75% could not name a vitamin-A-rich food. It is precisely this kind of evaluation data that frequently is used by opponents to illustrate that educational approaches don't work! But can we blame this failure on the educational approach, or should we admit that we have been ineffective communicators in the educational component of the currently operational high-dose programmes? Often we ask overburdened, unmotivated, and minimally trained delivery personnel to get the message out. Or we determine that only those who have higher education have sufficient knowledge to effectively compose and communicate the message, whereas those to whom we want most to relate are underprivileged and often lack formal education and access to other social programmes. But they are survivors. As survivors they have had to make choices - choices that include which of the many messages they hear and programmes forced upon them they will choose to act upon in the use of their limited resources, both of time and of money. Choice, however limited, is valued irrespective of socio-economic status.

People change practices when they are convinced that the change is to their benefit and they choose to change. Choice is too frequently left out of approaches to solving public health problems, including vitamin-A intervention strategies. Most universal capsule distribution programmes do not entertain choice as an option, yet targeted recipients for such programmes choose not to participate in increasing numbers in successive rounds, as evaluations of the Bangladesh and other national programmes illustrate. Indeed, proponents of fortification programmes proclaim the lack of choice as the major advantage of a fortification strategy. But, as occurred with the sugar fortification programme in Guatemala, as effective as the programme was shown to be while operational, the situation deteriorated rapidly when it was disrupted by internal political and economic changes. No demand for continuation of the programme had been created among the passive recipients.

How can the concept of choice be introduced into strategies for the prevention and control of vitamin-A deficiency? Just as with any other programme, there is not likely to be a universally applicable answer. Each situation has to be evaluated at the national, community, and family levels. The important point is that choices usually do exist if imagination and innovative thinking are applied, and these choices could be made available when considering strategies at each level of intervention. In some instances where clinical deficiency is rare, a national programme to improve the intra-country preservation, storage, and year-round availability of vitamin-A-containing foods, combined with an effective programme to improve consumption, might be an appropriate alternative to a high-dose programme. Elsewhere, a community-based feeding programme, a community- or family-level income-generation programme to provide economic resources to permit a choice of appropriate foods, or a kitchen/community garden may be alternatives - and these programmes are not mutually exclusive. Until we create a demand for a programme or a product, i.e. convert programme recipients into programme consumers, whether for a high-dose capsule, lower-cost green leafy vegetables, or better means of preparing and preserving vitamin-A-rich foods for feeding young children, it is difficult to conceive of achieving the effective sustained behavioural change that must occur to eradicate and control vitamin-A deficiency as a public health problem.

Reference

1. Daraton-Hill 1, Sibanda F. Mitra M, et al. Distribution of vitamin-A capsules for the prevention and control of vitamin-A deficiency in Bangladesh. Food Nutr Bull 1988;10(3):60-70.

Breast milk the life saver: Observations from recent studies

Karima A. Dualeh and Fitzroy J. Henry

Breast milk is universally accepted as the best food for infants, and its desirable properties have been extensively described [1]. This paper reviews the results of recent studies that improve our understanding of the role of breast-feeding in child health and survival and concludes that, despite much recent attention, breastfeeding is still much undervalued.

Four important questions are considered:

• Do exclusively breast-fed children grow better than breast-fed infants who receive supplements?
• To what extent does breast-feeding reduce infections?
• When does prolonged breast-feeding result in malnutrition?
• Does prolonged breast-feeding improve survival?

The growth of exclusively breast-fed children

In 1980, Waterlow and colleagues linked infant mortality with growth faltering [2]. Data presented from several countries in the developing world indicated a decline in the growth rate of infants between the ages of three and four months when compared with the mean for the United Kingdom. Waterlow further showed that, theoretically, after three months of age breast milk alone was insufficient to sustain adequate growth [3]. Inadequate production of breast milk by undernourished mothers would contribute further to growth "faltering" and lead to a degree of relative malnutrition in their offspring, which would increase mortality at this age. Recent studies have attempted to clarify this issue.

A study of 96 exclusively breast-fed infants in the United States indicated that most of these children grew adequately without supplementation during the major part of their first year of life [4]. However, in Australia the weight increments of healthy exclusively breast-fed infants fell below the UK standard of normal growth after three months of age [5]. These and other studies that have attempted to link prolonged exclusive breast-feeding directly with growth [6; 7] are still controversial and inconclusive. One problem is that these attempts to identify an age at which exclusive breast-feeding becomes inadequate are limited by individual variations and self-regulation controls within the infant [8-10].

Ultimately, all infants must be weaned, but the question remains as to when the risk for the infant from malnutrition due to the inadequacy of breast milk is greater than the risk from diarrhoea due to early supplementary feeding, which invariably introduces contamination I 11]. To answer this question it is necessary to consider the influence of infections on the relationship between feeding and growth.

Studies in urban Gambia have shown that, although infants spent 15% of their time ill with diarrhoea, the impact of this load of infection on growth was felt mainly by those who were mixed-fed during weaning, not by the children who were exclusively breast-fed [12]. In the Sudan a similar pattern of effect was observed even though diarrhoea was less prevalent there 113]. These studies did not consider the effect of infection on nutrient intake, but they do indicate that breast-feeding reduces the impact of infections on growth.

To what extent does breast-feeding reduce infections?

Studies in poor communities have shown that breast fed infants have lower diarrhoeal morbidity than other, otherwise similar, infants [14]. Infants who receive no breast milk are at greater risk than those who are exclusively breast-fed [15]. Furthermore, breastfeeding may reduce the severity of diarrhoeal disease [16] and also morbidity from other illnesses, including acute respiratory infections, meningitis, measles, and allergies [17]. One major consequence of infectious disease, particularly diarrhoea, is reduced food intake [18; 19]. However, in one community in Bangladesh, only minor decreases in intake were noted for rural children with diarrhoea l20]. Moreover, in those hospitalized, anorexia was responsible for a substantial reduction in intake of supplemental foods, but the intake of breast milk was apparently unaffected [21].

In summary, these studies suggest that breastfeeding, both exclusive and partial, appears to reduce the severity of diarrhoea and also lessens the effect of reduced nutrient intake that commonly accompanies an attack. The protective effects of breast-feeding are presumed to be due to both the intrinsic anti-infective properties of breast milk and to reduced exposure to contaminated foods. But do breast-fed children experience fewer infections?

When does prolonged breast-feeding cause malnutritions

It is recognized that breast milk alone is insufficient to support normal growth during the second half of infancy. For this, supplementary feeding is required [22]. But when does continued breast-feeding hamper the growth of children? Several recent studies have reported that prolonged breast-feeding (i.e. beyond 12 months) may be associated with a higher prevalence of malnutrition than is found in non-breast-fed children [23-26]. Recently, it was suggested that breast-feeding should stop at around 18 months [27] because nutritional status has been observed to be poorer at this age in children who are still being breast-fed.

Is there any clear biological reason why breast-fed children should be more malnourished after one year of age than fully weaned children even when they receive supplementary food? Breast milk has the highest energy density (calculated on the basis of dry weight) of all the foods consumed by children of this age in Bangladesh [28]. In Uganda consumption of energy was 17% higher for children over 18 months old who were breast-fed than for those who were not [29]. Similarly, in Kenya children 18-23 months old had 108% and 84% of their recommended daily calorie intake in the breast-fed and non-breast-fed groups respectively [30]. Studies in Zaire [31], New Guinea [32], and Bangladesh [33] have shown that children receive 500 to 600 ml of breast milk per day. Furthermore, women who are poorly nourished can produce up to 700 ml per day during the first six months and 300 to 500 ml per day in the second year [1]. In the lean pre-harvest season in Machakos, Kenya, breast-milk intakes averaged 405 ml per day for children 12

17 months old [30]. The protein content of breast milk has the highest biological value compared to other foods [1]. Furthermore, during extended lactation the composition of protein remained constant in studies in Côte d'Ivoire [34]. During the second year a mean daily protein intake of 2.2 g per kilogram of body weight was maintained in both Uganda [35] and Kenya [36].

Why, then, do breast-fed children tend to be more malnourished around two years of age even when their diet is supplemented with other foods? Is breastfeeding at fault? It should be noted that the studies mentioned above have not collected data on the frequency of breast-feedings or the volume of breast milk taken, or on the adequacy of other foods given to the child and other such information that may help to explain the poorer nutritional state. A recent unpublished observation by A. Briend and colleagues, however, indicates that breast-fed children who were about to be weaned had a lower nutritional status than those who continued breast-feeding. This means that cessation of breast-feeding is not the main cause of the poorer nutritional state. Hence, the mother of a malnourished child should not be advised to stop breast-feeding in an attempt to improve the child's dietary intake. Furthermore, the decision to stop breast-feeding should not be taken merely on the basis of a child's age.

Breast-feeding and survival

A recent case-control study in Brazil [37] shows that infants who received no breast milk were 14 times more likely to die of diarrhoea than exclusively breast-fed infants. Infants receiving animal milks in addition to breast milk were four times more likely to die of diarrhoea than exclusively breast-fed infants. Furthermore, with each additional daily breastfeeding, children showed a 20% decrease in the risk of death from diarrhoea [37]. Data from Bangladesh suggest that breast-feeding may protect against diarrhoeal mortality well into the third year of life [38].

The question is: When should breast-feeding stop? The suggestion that the age of weaning (the cessation of breast-feeding) should be 18 months [27] can be misleading and unwise under conditions still prevailing in Bangladesh. This is so because, despite the lower nutritional status of supplemented breast-fed children than of those weaned earlier [23-26], there is also good evidence that mortality in such children is substantially less both in hospitals [39] and in the community [38]. The findings indicate that supplemented breast-feeding can have a favourable impact on survival compared with full weaning even when it results in less than optimal nutritional status [38]. Hence, poorer nutritional status alone should not be the criterion for terminating breast-feeding, although it may indicate a need for better complementary feeding.

In Bangladesh women of low socio-economic status tend to breast-feed longer [40]. While this may account for the lower nutritional status of breast-fed children in Bangladesh as judged by anthropometric measurements, it should not be assumed that this is the result of breast-feeding per se, but rather of the lack of resources to obtain sufficient supplementary food. The protective effect of breast-feeding at this age is likely to be critical for the survival of malnourished children [41]. In fact, the protective effect of prolonged breast-feeding on survival was observed only in malnourished children. These studies lead to the conclusion that underprivileged mothers should be advised to breast-feed as long as possible, because human milk provides more than nutrition: it is a protection against diseases. It saves lives, particularly in the malnourished.

References

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3. Waterlow JC, Thomson AM. Observations on the adequacy of breast-feeding. Lancet 1979;2:238-41.
4. Ahn CH, MacLean WC Jr. Growth of the exclusively breast-fed infant. Am J Clin Nutr 1980;33:183-92.
5. Hitchcock NE, Gracey M, Owles EN. Growth of healthy breast-fed infants in the first six months. Lancet 1981 ;2:64-65.
6. Critical weight loss in breast fed infants. Nutr Rev 1983;41 :53-56.
7. Butte NF, Garza C, Smith EO, Nichols BL. Human milk intake and growth in exclusively breast-fed infants. J Pediatr 1984;104:187-95.
8. Ounsted M, Sleigh G. The infant's self-regulation of food intake and weight gain. Lancet 1975;1:1393-97.
9. Whitehead RG, Paul AA. Infant growth and human milk requirements. Lancet 1981;2:161-63.
10. Woolridge MW, Baum JO, Drewett RF. Does a change in the composition of human milk affect sucking patterns and milk intake? Lancet 1980;2:1292-94.
11. Waterlow JC. Observations on the suckling's dilemma: a personal view. J Human Nutr 1981;35:85-98.
12. Rowland MOM, Rowland SGJG, Cole TJ. Impact of infection on the growth of children from 0 to 2 years in an urban West African community. Am J Clin Nutr 1988;47: 134-38.
13. Zumrawi FY, Diamond H. Waterlow JC. Hum Nutr Clin Nutr 1987;41C:453-61.
14. Feachem RG, Koblinsky MA. Interventions for the con" trot of diarrhoeal diseases among young children: promotion of breast feeding. Bull WHO 1984;62:271-91.
15. Rowland MOM. In: Gracey M, ed. Diarrhoeal disease and malnutrition: a clinical update. Edinburgh: Churchill Livingstone, 1985:119.
16. Clemens ID, Stanton B. Stoll B. Shahid NS, Banu H. Chowdhury AKMA. Breast feeding as a determinant of severity in shigellosis. Am J Epidemiol 1986;123:710-20.
17. Cunningham AS. Morbidity in breast-fed and artificially-fed infants. J Paediatr 1979;95:685-89.
18. Mata LJ, Kronmal RA, Urrutia JJ, Garcia B. Effect of infection on food intake and nutritional state: perspectives as viewed from a village. Am J Clin Nutr 1977; 30:1215-27.
19. Martorell R. Yarbrough C, Klein RE. The impact of ordinary illnesses on the dietary intakes of malnourished children. Am J Clin Nutr 1980;33:345-50.
20. Brown KH, Black RE, Robertson AD, Becker S. Effects of season and illness on the dietary intake of weanlings during longitudinal studies in rural Bangladesh. Am J Clin Nutr 1985;41:343~55.
21. Hoyle B. Yunus M, Chen L. Breast-feeding and food intake among children with acute diarrheal disease. Am J Clin Nutr 1980;33:2365-71.
22. Mitzner K, Scrimshaw N. Morgan R. Improving the nutritional status of children during the weaning period. Cambridge, Mass, USA: MIT, 1984.
23. Victora GC, Vaughn JP, Martines JC, Barcelos LB. Is prolonged breast-feeding associated with malnutrition? Am J Clin Nutr 1984;39:307-14.
24. Chaudhury RH. The duration of breast-feeding adequacy in a rural area of Bangladesh. Food Nutr Bull 1984;6(1):44-49.
25. Thoren A, Stintzing G. Value of prolonged breastfeeding. Lancet 1988;2:788.
26. Michaelsen KF. Value of prolonged breast-feeding. Lancet 1988;2:788-89.
27. Brakohiapa LA, Yartey J. Bille A, et al. Does prolonged breast-feeding adversely affect a child's nutritional status? Lancet 1988;2:416-18.
28. Brown KH, Black RE, Becker S. Consumption of food and nutrients by weanlings in rural Bangladesh. Am J Clin Nutr 1982;36:878-89.
29. Rutishauser IHE. Factors affecting the intake of energy and protein by Ugandan pre-school children. Ecol Food Nutr 1974;3:213-22.
30. van Steenbergen WM, Kusin JA, van Rens MM. Lactation performance of Kamba mothers, Kenya: breast feeding behaviour, breast milk yield and composition. J Trop Pediatr 1981;27:155-61.
31. Vis LH, Hennart P. Rachababisha M. Some issues in breast feeding in deprived rural areas: maternal nutrition and breast feeding in the Kivu, Zaire. Assignment Children 1981;55156:183-200.
32. Becroft TC. Child rearing practices in the highlands of New Guinea: a longitudinal study of breastfeeding. Med J Australia 1967;2:598-602.
33. Roy SK, Rabbani GH, Black RE. Oral rehydration solution safely used in breast-fed children without additional water. J Trop Med Hyg 1984;87: 11 -13.
34. Lauber E, Reinhardt M. Studies on the quality of breast milk during 23 months of lactation in a rural community of the Ivory Coast. Am J ClinNutr 1979;32:1159-73.
35. Rutishauser IHE, Whitehead RG. Energy intake and expenditure in 1-3 year old Ugandan children living in a rural environment. Br J Nutr 1972;28: 145.
36. van Steenbergen WM, et al. Lactation performance. In: van Ginneken JK, Muller AS, eds. Maternal and child health in rural Kenya. Beckonham, Kent, UK: Croom Helm Ltd., 1984:153-65.
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Nutritional evaluation of an agricultural development project in southern Sri Lanka

Gerd Holmboe-Ottesen, Margareta Wandel, and Arne Oshaug

The effect that rural development programmes may have on the nutritional conditions of the target population has become a central issue in the international nutrition debate. The stated goals of such programmes do not usually include nutritional improvement but generally focus on raising the productivity of small-holder agriculturalists and on generating employment for and improving the living standards of the rural poor.

Several reports, however, have indicated likely negative effects on nutrition of various agricultural and rural development programmes [1-5]. There has also been a growing awareness that such programmes have a much greater potential for affecting nutritional conditions (for better or worse) than direct nutrition interventions, because they may have a more thorough and sustained impact on the society than nutrition interventions, which are mostly aimed at relieving symptoms.

This awareness has found expression in various forms in international forums. The Food and Agriculture Organization recommended to its member states that they should evaluate the impact their agricultural programmes had or could be expected to have on nutrition. At the nineteenth FAO General Conference, in 1977, the member states returned this recommendation, asking the FAO to prepare methodologies for evaluating the impact of its programmes and projects on nutrition [6l. Significant in this respect also was the endorsement by the World Conference on Agrarian Reform and Rural Development of including nutrition as an objective of rural development as well as an indicator for monitoring progress [7]. This has led to a number of desk studies and field work over the following years in the FAO and other concerned UN bodies, some bilateral agencies, and the research community [8-17].

This paper reports on a field study to assess the impact of an agricultural programme on an area's food and nutritional situation. The study was part of a larger research programme designed to develop methodology for evaluating the nutritional effects of rural development and agricultural programmes [1517]. It was used as a test case to try out methods and indicators.

The study was carried out in the Kirama Oya (river) basin, in the Hambantota District in south-eastern Sri Lanka, where the Norwegian Ministry for Development Co-operation is supporting an integrated rural development programme (HIRDEP). Two HIRDEP projects were in operation in the area, focused on raising the productivity of paddy cultivation: The Kirama Oya Irrigation Scheme dealt with rehabilitating and reconstructing an old irrigation system along the Kirama Oya. The Paddy Cultivation Project was concerned with introducing modern cultivation techniques, a credit system for agricultural inputs, proper water-management practices, and a scheme for crop insurance.

The research project was started in 1981, before the construction work was finished, and ended in 1984. At the end of the research, the two development projects had been in full operation for one to two years, depending on the location of the different project sites in relation to the irrigation system.

Methods

General organization

The evaluation entailed an annual monitoring of the food and nutrition conditions from 1981 to 1984. To minimize the effect of seasonal variations, data were collected during the same period each year, in the course of a month during August/September, which is the pre-harvest period and the time of the lowest food availability.

The monitoring consisted of two parts: a community-level survey and a household survey. In the former, data were collected through interviews with key informants, discussions with groups of farmers, and visits to project sites. The data included information on price and wage levels, project performance, conditions for agricultural production, and the activities of formal and informal institutions.

The household survey consisted of a questionnaire interview administered to the individual households and anthropometric measurements and clinical examination of selected pre-school children in the households. This survey was done in 1981, 1982, and 1984 only.

Sample

Eleven villages, representing every other village on either side of the Kirama Oya, were selected for the initial study in 1981. A subsample of 32 out of 55 sections (godas) within these villages was chosen for subsequent monitoring in 1982-1984. In addition to the original villages, one more village, comprising three Sodas, was included in the last two monitorings. The selection of Sodas was made strategically so as to contain population groups involved in different economic activities and of different degrees of involvement in the Kirama Oya projects. This enable us to study nutritional changes in different groups that were bath directly and indirectly affected by these projects.

A random sampling of the pre-school children, covering one-third of the pre-school population, was carried out each survey year in each goda monitored by taking every other pre-school child in the households visited for anthropological measurement. This method of sampling resulted in the inclusion of more than one child per household in a few cases. For this reason, the number of children included in the total samples for each survey year exceeded the number of households by about 4%.

The sample sizes for the three surveys were: 611 children from 586 households in 1981, 468 children from 450 households in 1982, and 466 children from 449 households in 1984. For the purpose of comparing nutritional status in 1981, 1982, and 1984, a subsample was drawn for each year comprising only children from the godas that were included in all three survey years. These subsamples contained 399, 426, and 424 children respectively (table 1).

Data collection

For the assessment of nutritional status, the weight and height of children 6 to 60 months old were measured using Salter spring balances and measuring boards. Their ages were determined from their birth certificates. These data were combined for the three indicators of nutritional status: weight for age, height for age, and weight for height. The cut-off points used to classify nutritional status on the basis of these indicators were those recommended by the WHO [18] and used in the Sri Lankan National Nutrition Surveys: general malnutrition was defined as weight below 75% of the WHO reference standard weight for age, chronic malnutrition as height below 90% of the standard height for age, and acute malnutrition as weight below 80% of the standard weight for height.

The analysis of changes in nutritional status was based on the determination of the prevalence of malnutrition according to the respective cut-off points for the three indicators and the distribution of the sampled population according to these indicators.

A Gaussian normal distribution within the samples of all three years of monitoring was demonstrated for all three indicators. The presentation of data on nutritional status therefore includes mean values and standard deviations expressed in percentages of the WHO standards for the indicators, as well as the proportion of cases falling below the cut-off points (the prevalence rate).

The analysis of differences of change in nutritional status between various socio-economic subgroups revealed that changes had generally occurred in the prevalence of both acute and chronic malnutrition. However, the low prevalence of both types of malnutrition and the small size of the samples in the subgroups gave a very low reliability for the height-forage and weight-for-height indicators. For this reason and for simplicity, the indicator of general malnutrition, weight for age, which may reflect a combination of chronic and acute malnutrition, is presented when the sample is divided into subgroups.

A socio-economic score was calculated for each household according to a method adapted from Smith [19] and Hesselberg [20]. Data were collected on the possession of certain household items known to be related to socio-economic status in the Kirama area. Ten such items were identified and listed in the questionnaire, and the respondents were asked, for each item, whether they possessed it and in what quantity. A standard profile was worked out for the project area in terms of which and how many of the items an average household had. The score assigned to each household was based on its deviation from the standard profile and a weighted index given to each item according to its necessity and cost.

The socio-economic score was used to classify the households into subgroups of "low," "medium," and "high" socio-economic status. The cut-off points between the three subgroups were chosen on the basis of in-depth data collected from a village selected as a case in the research programme [6] which was considered to be typical for the area in its socio-economic profile. The cut-off points were chosen so as to distribute the households of this village evenly between the three groups.

Income data were collected from each productive member in the household. Various sources of income, both in cash and in kind, were calculated for the preceding year and added for an estimation of the total household income.

To assess the intake of energy-rich foods, the respondents were asked to recall the previous day's consumption of three staples - rice (uncooked), coconut, and sugar - for the total household. If rice was not eaten at a meal, the quantity of a substitute (e.g. bread, jack-fruit, noodles) was given. These foods were selected as indicators because they represent a large proportion - 70%-90% [6l - of the daily energy intake. In addition, it was easy for the respondents to estimate the quantities of these items eaten by the total household.

Information on how many persons the previous day's meal was cooked for was also obtained and used to estimate the intake per consumption unit. The conversion factors for estimating the number of consumption units per household were based on the FAO/ WHO recommendations for energy intake according to age and sex [21]. A male 16-19 years old was set equal to one consumption unit, and other household members were counted as fractions of a unit in proportion to the recommendations.

The significance of differences in the nutritional-status indicators and other variables was calculated by Student's t-test. Probabilities of differences at the level of .05 were regarded as statistically significant.

Results

Changes in nutritional status

As shown in table 1, there was virtually no change in the prevalence of general, chronic, and acute malnutrition among pre-school children in the total sample from 1981 to 1982. In contrast, the general nutrition status improved significantly from 1982 to 1984, with general malnutrition declining from 31.4% to 24.8%. A slight decline could also be detected in the prevalence of chronic malnutrition, but this change was not significant.

These findings are in agreement with the information obtained in the community survey on the food and agricultural situation in the area. This was very much the same during the monitoring in 1981 and 1982. The area was afflicted by drought in both years, which made cultivation difficult. Furthermore, the projects under HIRDEP were still in their initial phases, and construction work was taking place under the Kirama Oya Irrigation Scheme. Therefore, positive effects could not be expected at that stage. In the period 1982-1984 climatic conditions improved, and the construction work on the irrigation scheme was completed. Also, the farmers were beginning to reap benefits from the Paddy Cultivation Project.

TABLE 1. Changes in children's nutritional status from 1981 to 1984 in total sample

	No. of subjects	% of standard		Malnourished (%)a
		Mean	SD
Weigh/age
1981	399	79.1	9.5	30.6
1982	426	79.2	8.9	31.4
1984	424	80.6*	10.1	24.8
Height/age
1981	399	94.3	4.6	13.0
1982	426	94.8	4.6	11.3
1984	424	95.2	4.7	9.0
Weight/height
1981	399	87.6	6.9	9.8
1982	426	87.9	6.2	9.0
1984	424	88.1	7.3	9.2

Only sections of villages participating in all surveys are included.

a. Children below 75% of standard for weight for age (general malnutrition); below 90% of standard for height for age (chronic malnutrition); below 80% of standard for weight for height (acute malnutrition).
* Difference between 1982 and 1984 is significant (p = .04).

The following comparison of nutritional data therefore focuses on differences between the 1982 and 1984 surveys. The comparison of the 1981 and 1982 data can be viewed merely as a check on the reliability of the estimations of nutritional status.

It was found that nutritional status improved in all age groups (table 2). It could also be noted that the degree of general malnutrition seemed to increase with age. In the further analysis when the total sample was divided into socio-economic groups, the numbers within each age range were too small to allow a statistically significant comparison between the two years.

The general improvement of nutritional status in the Kirama area occurred upstream, in the northern part, while there was no improvement downstream, in the south (table 3). This was true for changes in all three indicators of nutritional status when expressed as the mean value of the percentage of the WHO reference standards. When expressed as prevalence of malnutrition, the difference between the two areas was seen only for general and chronic malnutrition.

Table 2. Changes in children's nutritional status as indicated by weight for age (general malnutrition) from 1982 to 1984, according to age groups (total sample)

Age (months) and year	No. of subjects	% of standard		Malnourished (%)a
		Mean	SD
6 -12
1982	63	83.7	10.9	15.9
1984	59	85.7	10.4	15.3
13 - 24
1982	105	79.2	8.2	25.7
1984	88	80.0	12.5	22.7
25-36
1982	102	79.1	8.7	30.4
1984	99	80.9	9.0	17.2
37-48
1982	82	77.3	7.5	34.1
1984	87	78.5	8.3	29.9
49-60
1982	71	75.2	7.5	52.1
1984	91	77.2	8.6	36.3

a. Children below 75% of standard weight for age

TABLE 3. Changes in children's nutritional status as indicated by weight for age from 1982 to 1984 in various groups in the Kirama Oya basin area

	No. of subjects	% of standard		Malnourished (%)
		Mean	SD
Geographical areaa
Northern
1982	187	78.1	9.1	38.5
1984	185	80.8*	10.1	21.6
Southern
1982	239	79,3	8,6	26,4
1984	239	79.6	10.1	27,2
Socio-economic status
Low
1982	225	77,9	8,7	36,0
1984	225	80,6**	11,1	23.6
Medium
1982	141	80,1	8,6	23,4
1984	143	80,0	9.4	23.7
High
1982	102	81.2	9.0	19.6
1984	98	82.1	9.0	18.4
Farming groupb
Kirama
1982	72	77.3	7.7	36.2
1984	90	81.6**	11.5	20.0
Non-Kirama
1982	98	80.6	9.3	25.5
1984	81	79.6	9.3	29.6
No paddy land
1982	298	79,4	8,9	32,6
1984	295	80,8(*)	9.9	25.0

a. One township is excluded from the sample.
b. See text for explanation of groups.
* p < .05.
** p < .01.
(*) p = .07.

Table 4. Difference in characteristic of subgroups in 1982 and 1984 samples

	No. of Subjects	Mean age (months)	Paddy land (acres per households)
Kirama
1982	72	28.2	2.1
1984	90	33.4*	2.0
Non-Kirama
1982	98	32.0	1.7
1984	83	34.5	1.6
No paddy land
1982	297	31.5	---
1984	293	32.1	---

*p=.03

There was no difference in the mean area of paddy land held by the two groups in the two years that could explain why a positive change was seen only in the children of the Kirama farmers. There was, however, a difference in age distribution between the two years, the mean age of the children in the 1984 sample being higher than that in 1982. However, the effect of this difference would be expected to be an increase in malnutrition rather than a decrease, since malnutrition seems to increase with age in this area (see table 2). The improvement found in the nutritional status of the children of the Kirama farmers' group seems therefore not to be due to differences in the sample characteristics for 1982 and 1984.

TABLE 5 Changes in daily intake of selected staple foods from 1982 to 1984

	No of households	Intake (g /CU)			Summed intake (kcal/CU)
		Rice	Coconut	Sugar
Total sample
1982	450	429	118	36	2,138
1984	449	470(*)	114	50***	2,395*
Geographical areaa
Northern
1982	187	441	115	27	2,087
1984	185	477(*)	110	42***	2,323***
Southern
1982	239	438	128	39	2,201
1984	239	463	124	55***	2,390
Socio-economic status
Low
1982	216	403	105	26	1,977
1984	218	476(*)	114	45***	2,429*
Medium
1982	134	457	125	37	2,218
1984	135	476	115	53***	2,373
High
1982	100	452	138	56	2,391
1984	96	447	115**	59	2,313
Farming group
Kirama
1982	72	504	137	40	2,413
1984	87	490	122	52***	2,435
Non-Kirama
1982	95	463	130	41	2,280
1984	81	465	120	52(*)	2,350
No paddy land
1982	283	402	110	34	2,027
1984	281	464*	110	49***	2,385

CU = consumption unit.
a. One township is excluded from the sample.
*p<.05.
**p<.01.
***p<.001.
(*).05<p<.08.

Changes in intake of staple foods

In the Kirama area as a whole, there was an overall increase of 12% in the energy intake per consumption unit from the three recorded staple foods (table 5). The difference in the total intake of energy from these three foods between 1982 and 1984 was significant. The intake of rice in 1984 was 9.6% above that in 1982; however, this difference was not significant (p = .06). The intake of sugar rose significantly by 38%. A slight, but not significant, decline of 3.4% in the intake of coconut was recorded.

In 1982 the intake of coconut and sugar and of total calories from the three foods was somewhat larger in the southern part of the Kirama Oya basin than in the north. The increase in intake from 1982 to 1984 was larger in the north, however, in both absolute and relative terms.

TABLE 6. Changes in disease patterns from 1982 to 1984 (percentages of households with sick children)

	No. of households	Fever	Diarrhoea	Worms	Colds	Abscess	Malaria
Kirama
1982	72	1.4	4.2	12.5	19.5	5.6	0.0
1984	87	13.8	6.9	6.8	5.6	4.6	1.1
Non-Kirama
1982	95	8.4	1.1	8.5	20.0	5.3	0.0
1984	81	12.3	3.7	9.8	24.7	3.7	1.2
No paddy land
1982	283	5.3	2.5	7.5	18.4	6.1	0.4
1984	281	7.8	3.6	7.1	34.9	5.0	0.0

The greatest positive changes in the intake of the three foods took place in the lowest socio-economic group. This finding is in accordance with the data presented on nutritional status, which show a similar pattern. Apart from a decrease in the intake of coconut, there were no significant changes in intake of the other staples or in total energy intake in the highest socio-economic group.

There was almost no difference in energy intake between 1982 and 1984 in the households of the Kirama farmers. The intake of rice remained almost the same. A slight, but not significant, positive change occurred in the energy intake of the non-Kirama farmers' group. However, the intake of rice remained the same even in this group. In the households without paddy land a significant increase of 18% in the energy intake between 1982 and 1984 was recorded, and this group also showed a significant increase in the consumption of rice. Sugar consumption rose in all three groups. The increase was less in the two paddy farmers' groups, however, than in the group without paddy land, which in turn had the lowest consumption in both years.

Thus, the positive change in the nutritional status of the Kirama farmers' children was not a reflection of increased intake of these selected staple foods in the households. It should be noted, however, that the Kirama farmers had a higher intake of rice and coconut in both years than the other groups.

Changes in food prices

The above intake data must be seen in relation to the increase in food prices that took place during the two year period. The price of rice went up by 40%, that of coconut about 200%, and that of sugar 10%. Right before the monitoring in 1982, the price of sugar had jumped about 41)%. This implies that sugar consump tion was probably below normal in 1982. The high price increase of coconut explains why a general decline in coconut consumption was recorded. A food-basket index especially designed for the Kirama area showed that the overall inflation rate on food was 55% [17].

Changes in hygienic conditions and disease patterns

General hygienic conditions and access to hygienic toilet facilities did in fact improve somewhat over the two years for the three groups. However, this improvement was of the same magnitude for all the groups.

There were more colds and fever symptoms as well as more diarrhoea in all the groups in 1984 than in 1982 (table 6). The increase in these diseases and symptoms was particularly pronounced among the Kirama farmers. Concomitantly there was a decrease in intestinal-worm infections in this group that was not seen in the other groups. All in all, however, the pattern of change in the prevalence of disease and symptoms could not explain the improvement of nutritional status among the Kirama farmers' children. Since the prevalence rate for most diseases and symptoms, particularly diarrhoea, increased from 1982 to 1984, one would have expected a negative impact on nutritional status rather than the positive change that was recorded.

Changes in production and socio-economic indicators

Because of the drought conditions in 1982, many of the farmers did not cultivate their paddy land, and the failure rate was high among those who did. Therefore, the analysis of paddy production data is focused on a comparison between the harvests of the Kirama farmers' and the non-Kirama farmers' groups in 1984 (table 7). The yields were generally better in the north than in the south. Also, the Kirama farmers had higher yields than the other farmers. It was found that these higher yields were due to the successful operation of the Kirama Oya projects [17].

TABLE 7. 1984 paddy production data

	No. of households	Total harvest (bushels/plot)	Share of harvest (bushels/household)	Yield (bushels/acre)	Plot size (acres)
Geographical area
northern	56	57.8 (30)	44.0 (24)	35.7 (33)	1.5 (1.0)
southern	103	37.5 (27)	27.6 (18)	23.5 (18)	1.9 (1 5)
Farming group
Kirama	87	57.3 (42)	43.0 (27)	30.1 (26)	2.1 (1.5)
Non-Kirama	81	30.0 (18)	20.8 (12)	24.3 (20)	1.5 (1.0)

Principal data are means. Figures in parentheses are medians.

TABLE 8. Changes in household income and socio-economic status from 1982 to 1984

	No. of Households	Total income (rupees/household)	Increase in income (%)	Socio-economic score
Total sample
1982	450	6,424		0.0
1984	449	9,934***	54.6	0.1
Geographical areaa
Northern
1982	187	4,991		-4.5
1984	185	9,419***	88.7	-3.1
Southern
1982	232	6,977		2.3
1984	228	10,081***	44.5	2.3
Socio-economic status
Low
1982	216	4,429		-9.3
1984	217	7,194***	62.4	-8.8
Medium
1982	134	6,431		0.1
1984	134	9,779***	52.1	0.5
High
1982	100	10,819		19.9
1984	98	16,554***	53.0	19.5
Farming group
Kirama
1982	72	7,070		3.9
1984	87	11,117*	57.2	5.8
Non-Kirama
1982	95	7,817		5.2
1984	81	12,168**	55.7	5.3
No paddy land
1982	283	5,810		-2.7
1984	281	8,950***	54.0	-3.2

a. One township is excluded from the sample.
* p < .02.
** p < .01.
*** p< .001.

The income level in the total sample rose on the average by 55% from 1982 to 1984 (table 8). This increase was at the same level as the rate of inflation for foods in the area. While income was higher in the south than in the north, the increase in income between the two survey years was higher in the north in both relative and absolute terms; it was 88%, far above the inflation rate for foods. The increase in income was significant for all the groups investigated. The non-Kirama farmers had a somewhat larger income than the Kirama farmers in both years; however, the increase was approximately the same in both groups in absolute as well as in relative terms.

The socio-economic score was much lower in the northern part of the area than in the south (table 8). There was no change in this indicator in the south between 1982 and 1984 and a positive, but not significant, change in the north. There were small positive changes in the socio-economic scores of the lower socio-economic groups. The score changed positively, but not significantly, in the Kirama farmers' group; there was virtually no change in the non-Kirama farmers' group and a slight negative change for the households without paddy land.

Discussion

Evaluation will always be fraught with difficulties with regard to separating the effects of a project from other changes that may have occurred in the socio-ecological environment during the project period. In the present research programme, an attempt was made to overcome this problem by combining quantitative and qualitative data that could give an insight into factors and processes, both internal and external to the two agricultural projects, influencing the nutritional conditions. For this purpose, nutrition monitoring was combined with a case study on the food and nutrition conditions in a village within the project area, with a special focus on women's opportunities to cater for their children's nutritional needs [22]. Furthermore, the monitoring at the household level was combined with community-level data on ecological and institutional factors, as well as the monitoring of prices on food, agricultural inputs, and agricultural wages [17].

The main purpose of this study was to assess the nutritional impact of an agricultural project on the household, and not on the individual. The nutritional status of children was thus used as an indicator of the food and nutrition situation of the household. This approach has obvious pitfalls. It is built on the assumption that the main causes of undernutrition among the children are related to shortage of food in the household rather than problems related specifically to adequate child feeding. Thus, the relevance of this approach would vary in different societies, depending on the nature of the nutrition problems.

In the case study focusing on women, we found that the most important limitation in regard to adequate child nutrition was the lack of material resources needed for procuring food, and not a lack of knowledge or time on the part of the women [22]. The feeding of small children was a high priority in the households. Women also had a high degree of knowledge about nutrition, health, and sanitation due to their general high level of education. Furthermore, they were not so overburdened with work that this hampered their ability to cock and care for their children, as had been found in many other societies [23]. One could therefore expect that whenever food supplies available to the household increased, the children would benefit as well as the adults. Thus, child nutrition seems to be a more relevant indicator of the overall nutritional condition of the household in this society than in many other societies, where the limitations on adequate child nutrition are more related to women's poor nutritional knowledge and lack of time.

As mentioned earlier, this research was carried out during a time of dramatic climatic changes in the Kirama area. The results must therefore be interpreted against the background of a process of general recovery from a drought. The fact that the improvement in nutritional status was most prounounced in the households of the lowest socio-economic stratum indicates that this group was probably the hardest hit during the drought and in fact was "buffering" the impact vis-à-vis the higher-income groups.

The nutritional improvements observed in the north were not found in the south. These improvements were also associated with greater increases in real income and in socio-economic scores and higher paddy yields in the north. In the south, contact with urban areas creates better employment opportunities outside the agricultural sector. The northern part of the Kirama area is more rural and isolated, and its people are more dependent on agriculture. Furthermore, the people are poorer than in the south, which also makes them more vulnerable to climatic changes. It is reasonable to conclude that the drought hit people in the north harder than in the south and resulted in more severe declines in income, food consumption, and nutritional status. At least some of the improvement that was seen in the north thus could be explained as recovery from a temporary bad situation over and above that which was found in the south.

There are, however, strong indications that the Kirama projects also had a positive nutritional impact on the people in the north. Through interviews with extension workers and discussions with farmers, it be came clear that one reason for this was that the Kirama Oya Scheme functioned best in the north. In addition, the Paddy Cultivation Project was only carried out in the north, and those Kirama farmers participating in it had almost double the yield of those who did not participate. The Kirama Oya projects must also have had a positive effect on the households in the north that were dependent on casual labour to make a living. Information from the case study revealed that paddy farmers were more likely to employ casual labour when they were reasonably assured of a successful harvest [17].

The specific impact of the development projects was also indicated by the finding that the nutritional status of the Kirama farmers' children improved significantly, while that of the children of the other paddy farmers remained the same. It should be noted, however, that the nutritional status of the Kirama farmers' children was exceptionally bad at the outset of the evaluation in 1981 and 1982. The general improvement in the food situation could therefore be expected to have a larger positive impact on them since they were more malnourished than the others. On the other hand, the improvement was so pronounced that the nutritional status of the Kirama farmers' children at the last monitoring, in 1984, was better than that in the other group.

Thus the effects of the Kirama Oya projects came in addition to the general impact of the improved climatic conditions in the area. This explanation is supported by the higher paddy yields and the increase in socio-economic score among the Kirama farmers, which was not found among the non-Kirama farmers.

Improved child nutritional status was associated with an increased consumption of the staple foods selected as dietary indicators in the most disadvantaged groups, i.e. the poorest and the ones in the north (table 5). In these groups, however, most households were only indirectly affected by the Kirama Oya projects. In the group directly affected, the Kirama farmers, the change in child nutritional status was not associated with changes in the consumption of these foods. A possible explanation for this is that the Kirama farmers were better off economically than the other groups in the area (table 8) and that an increase in socio-economic status above a certain level is not associated with a higher intake of rice and total energy from these staples (see table 5). In support of this interpretation is also the finding that among the paddy-farmer groups there was no positive linear relationship between the size of paddy harvest and the household consumption of rice and the other staples. The intake of these tended to stay level regardless of the size of the harvest.

Since the dietary indicators used here comprise only three staple foods, the possibility is not excluded that overall dietary improvement actually occurred in the Kirama farmers' group. Observations reported elsewhere [17] demonstrated that, when family income increases, a greater proportion of the diet comes from other supplementary foods, such as fish and vegetables. Because of the lack of sensitivity of the method for registration of supplementary foods, no conclusive evidence for an increased intake of supplementary foods could be shown in the Kirama farmers' group. However, a positive effect of improved family income was observed [17].

The positive nutritional effects of the projects in the Kirama Oya basin can be related to the particular socio-cultural setting in the area. Most significantly, the projects were concerned with the cultivation of a food product that is very important nutritionally as well as culturally for the people concerned. Apart from playing an important role in the daily diet, rice is also one of the most important cash crops in the area. Furthermore, it is easy to store, and a surplus can prevent seasonal fluctuations in food availability.

The experience from this study emphasizes the need to find appropriate indicators for nutrition monitoring that are relevant in a particular socio-economic setting to apply in assessing the impact of agricultural projects. The use of children's nutritional status as an indicator of the nutritional conditions of the household may not always be applicable. This variable should if possible be supplemented by measuring the weight of other household members.

The problem of finding relevant dietary indicators is particularly pertinent. Such indicators must be easy to collect but at the same time valid and sensitive enough to register quantitative changes in the diet. In this case the indicators of household food consumption registered changes in the lower socio-economic strata but not among paddy farmers who were better off.

The usefulness of applying a combination of different methods and approaches should be noted. This approach made it possible to interpret the nutritional changes in relation to important factors and processes in the society, and to launch hypotheses concerning the possible mechanisms of nutritional impact caused especially by the two agricultural projects in question.

Acknowledgements

We are grateful to Dr. Davy Perera, of UNICEF, Colombo, and Wenche Barth Eide, of the Institute for Nutrition Research, University of Oslo, for their contributions to this study. They participated in the planning team of the larger research programme of which this study was a part. This programme was funded by the Norwegian Agency for International Development (NORAD).

References

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4. Dewey KG. The impact of agricultural development on child nutrition in Tabasco, Mexico. Med Anthropol 1980;4:2143.
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7. FAO. The peasants' charter. Declaration of principles and programme of action of the World Conference on Agrarian Reform and Rural Development. Rome: FAO, 1981.
8. FAO. Integrating nutrition into agricultural and rural development projects: a manual. Nutrition in agriculture, no. 1. Rome: FAO, 19R2.
9. FAO. Selecting interventions for nutritional improvements. Nutrition in agriculture, no. 3. Rome: 1983.
10. FAO. Integrating nutrition into agricultural and rural development projects: six case studies. Nutrition in agriculture, no. 2. Rome: FAO, 1984.
11. Mason JIB. Data needs for assessing the nutritional effects of agricultural and rural development projects: a paper for project planners. Nutrition in agriculture, no. 4. Rome: FAO, 1983.
12. Pinstrup-Andersen P. Nutritional consequences of agricultural projects: conceptual relationships and asessment approaches. Staff working paper. New York: World Bank, 1981.
13. ACC/SCN. Nutritional impact of agricultural projects: taking nutritional effects into account in agricultural and rural development projects - concepts and methodology. Proceedings of a workshop held by ACC/SCN, IFAS, Rome, 1983.
14. USDA/USAID. Adding a food consumption perspective to farming systems research. A report prepared under the project "Nutrition Consumption Analysis of Agricultural Policies." Washington, D.C.: USDA Office for International Cooperation and Developmen/USAID Office of Nutrition, 1985.
15. Eide WB, Holmboe-Ottesen G. Oshaug A, Perera D, Tilakaratna S. Wandel M. Introducing nutritional considerations into rural development programs with focus on agriculture: 1. A theoretical contribution. Oslo: Institute for Nutrition Research, University of Oslo, 1985.
16. Eide WB, Holmboe-Ottesen B. Oshaug A, Perera D, Tilakaratna S. Wandel M. Introducing nutritional considerations into rural development programs with focus on agriculture: 2. Towards practice. Oslo: Institute for Nutrition Research, University of Oslo, 1986.
17. Eide WB, Holmboe-Ottesen B. Oshaug A, Perera D, Wandel M. Introducing nutritional considerations into rural development programs with focus on agriculture: 3. A case study: nutritional evaluation of Kirama Oya basin development scheme in Hambantota, Sri Lanka. Oslo: Institute for Nutrition Research, University of Oslo, 1986.
18. WHO. A guideline for the measurement of the nutritional impact of supplementary feeding programmes aimed at vulnerable groups. Geneva: WHO, 1979.
19. Smith DM. Where the grass is greener. Harmondsworth, London: Penguin, 1979.
20. Hesselberg J. A method of level of living analysis in the third world. Norsk Geografisk Tidsskrift 1984;38:37-42.
21. FAO/WHO. Energy and protein requirements. FAO nutrition meetings report series, no. 52. Rome: FAO, 1972.
22. Wandel M, Holmboe-Ottesen G. Women as nutrition mediators: a case study from Sri Lanka. Ecol Food Nutr 1988;21:117-30.
23. Holmboe-Ottesen G. Mascarenhas O. Wandel M. Women's food chain activities and implications for nutrition, problems and policy issues: report on the "state of the art" of recent research and its practical implications. Rome: ACC Sub-committee on Nutrition, FAO (in press).

Functional effects of iron deficiency: Cognition*

The following is the summary report of the Conference on Iron Deficiency and Brain Function, held at World Health Organization headquarters in Geneva, Switzerland, 10-12 October 1988, sponsored by the United Nations University and the Sub-committee on Nutrition of the UN Administrative Committee on Co-ordination (ACC/SCN) in collaboration with the WHO and the International Nutritional Anaemia Consultative Group (INACG).

Four main questions were posed at the beginning of the conference:

• Is there a statistical association between body iron status and behaviour? - If such a relationship exists, is it causal?
• What are the mechanisms by which this relationship is expressed?
• How valid is a generalization from current findings to other populations and ecological settings?

The meeting focused on a critical evaluation of seven experimental human studies of iron interventions on infants and schoolchildren (in Chile, Costa Rica, India, Indonesia, and Thailand). Presentations were preceded by reviews on behavioural developmental theory, the neurochemistry of iron deficiency, and animal models assessing impacts of iron deficiency on brain function. Two papers on methodological issues followed the presentations. A background paper included an algorithm to evaluate the degree to which causality can be inferred from the relationship between iron deficiency and behaviour.

The human studies assessed the effects of iron deficiency on measures of psychomotor development. attention, learning, and school achievement. None of the individual studies contained all the elements required to establish causality. Most were randomized, double-blind, iron-treatment trials. Results consistently showed that iron-replete children obtained better scores than iron-deficient anaemic children. Two studies (in Bandung, Indonesia, and India) reported that following iron treatment there was a significant improvement in test performance among anaemic children.

The following summary statement was approved at the end of the meeting:

Many studies have shown an association between iron deficiency and less than optimal behaviour in infants and children, as demonstrated by lower scores on tests of development, learning, and school achievement. A problem with interpretation of past studies has been that iron-deficiency anaemia is associated with other adverse environmental and nutritional conditions.

More recent studies using randomized designs with appropriate controls of variables have shown that iron therapy in children with iron-deficiency anaemia results in improvements in learning and achievement tests. This evidence in humans and a number of animal studies suggests that iron-deficiency anaemia is causally associated with less than optimal behaviour. For this reason it is important that iron-deficiency anaemia be prevented and treated.

Since the specific mechanisms and functional significance of these behavioural changes are not completely understood, further studies are essential bath to clarify the effects of iron-deficiency anaemia itself and to determine the importance of lesser degrees of such deficiency.

The inference made on causality was based on both statistical probability and biological and behavioural plausibility.

Critical questions raised during the discussions fall into three general areas for further investigation: (1) development of better measurement tools, (2) the search for mechanisms by which iron deficiency affects brain function and behaviour, and (3) con tinned research into the causal relationship between iron deficiency and behaviour.

Development of better measurement tools

Better infant tests are needed, especially for the use of measures for specific information processes (e.g. attention and memory) and for social and emotional development. Discussants recognized that the Bayley Scales of Mental and Motor Development have contributed to early identification of the effects of iron on infant behaviour, but questioned the construct validity of global scales of mental and motor development. Progress in this field might be accelerated by convening a workshop of development psychologists and neuroscientists to examine the problem and lay out research guidelines. Stops in this direction were taken by conference participants and officials from the Mental Health Division of the WHO.

Investigation of mechanisms

Participants recognized considerable progress in recent years in the study of brain neurochemistry as it relates to iron deficiency, illustrated by the experimental evidence presented on the effects of iron deficiency on the dopaminergic system and the reports suggesting that these effects may lie behind behavioural alterations. Neurochemical and behavioural research should be co-ordinated to draw more specific hypotheses on processes, loci of the effects, and mechanisms. Research should also assess the possible involvement of peripheral biological systems. Further research using animals was considered urgent; however, the relevance of animal models to the human organism must be established. Animal research should include: (1) cross-species verification, (2) development of models that mimic the type and severity of iron deficiency found in humans, and (3) recognition of development from concurrent biological, social, and behavioural perspectives. The relevance of currently available indicators of iron nutriture in the progression of iron deficiency should also be investigated.

Continued research into causality

While most of the investigations used a randomized, double-blind, iron-treatment trial to establish causality, substantial differences in the application of this design suggest that some standardization in methodology is needed to facilitate the evaluation of future research and strengthen conclusions about the generalizability of findings. Some co-ordination of research might be facilitated through multi-centre collaboration and communication.

Following are some critical issues that research designs should address:

• interactions between iron and other nutrients and infection,
• sensitivity and specificity of diagnostic strategies to minimize sample heterogeneity, - the impact of severity and duration of iron deficiency, and
• reversibility of effects.

At the meeting's end it was noted that current findings already have direct implications for both clinical treatment and public health interventions. However, treatment of iron-deficiency anaemia should not be justified solely on the basis of current knowledge. Continued research is needed to evaluate the potential importance of this public health problem on other programmes related to education and social/economic development.

Fostering nutrition among countries.

A workshop on Fostering Nutrition among Countries, sponsored by the International Union of Nutrition Sciences (IUNS), was held 26 April 1987 in San Diego, California, USA, at the time of the Third International Symposium on Clinical Nutrition. Attending the workshop were IUNS Council members, members of the US National Committee of the IUNS, and other scientists who had come to participate in the Clinical Nutrition Symposium. The workshop was chaired by Dr. Barbara Underwood (USA), a vicepresident of the IUNS.

There were four major presentations: two expressing views of the less-industrialized countries and two expressing those of industrialized countries. Dr. A. Valyasevi (Thailand) and Dr. J. E. Dutra de Oliveira (Brazil) described their experiences with projects involving collaboration with scientists or agencies from industrialized countries. Dr. J. G. A. J. Hautvast (Netherlands) and Dr. J. A. Olson (USA) spoke on their work in organizing collaborative projects in less-industrialized countries.

The presenters focused on five issues:

• examples of collaboration/co-operation between individual scientists or institutions, and the elements that led to success or failure;
• underlying principles to overcoming barriers to successful collaboration;
• areas most in need of collaborative efforts to advance nutrition in less-industrialized countries;
• the role of the IUNS and of regional and/or nation al nutrition societies;
• the role of international and bilateral agencies and private voluntary organizations.

Open discussion by all attendees followed the formal presentations.

The key points made by each of the invited speakers were as follows.

Dr. Aree Valyasevi listed seven institutions in Thai land that have been supported by, or have collaborated in, programmes of training or research with international and regional agencies, and institutions in the EEC, the United States, Japan, the Netherlands, and Australia. In some cases support was given to the institution and in others to individual scientists. He found that the most important factors favouring the more successful collaborations were:

• sound leadership and recognition of project leaders, domestic as well as foreign, because such recognition fosters favourable attitudes and creates trust;
• inclusion of less-developed-country personnel in planning and identification of needs from the beginning;
• dissemination of usable information from the project for the benefit of the country where the project is;
• the provision of matching available resources from the project country to stimulate concern about the project among that country's authorities and local participating staff, thus increasing the chance for continuation;
• creation of an academic atmosphere by the developed-country workers and their project-country counterparts to help update the latter and narrow the knowledge gap between them.

Barriers to successful collaborations can be minimized by:

• selecting less-industrialized-country staff who have potential for training and development and who will be in service for some time;
• strengthening capabilities for management and planning among project-country staff in order to upgrade their effectiveness, efficiency, and productivity;
• minimizing cross-cultural differences between industrialized-country and project-country staff and local people, e.g. by recruiting personnel from developed countries who are not only competent but sensitive, with careful orientation of visiting scientists;
• assuring professional recognition of local staff to sustain morale, motivation, and productivity.

Collaborations are needed to address issues both within and between less-industrialized countries. Within these countries help is needed in the critical analysis of existing research information and the development of strategies/mechanisms to apply research results to actual problems; in the development of concrete national food and nutrition plans; and in initiation or strengthening of networks for interdisciplinary collaborations.

Training centres and the development of graduate training programmes are needed between LDCs, as well as the creation of networks for information exchange. There are advantages to training schemes provided within the LDC or in a nearby region where the nutritional problems, socio-economic conditions, and environment are similar. Training is needed in nutritional science, in nutrition-related fields, and also in planning and management.

Collaborative projects should be relevant to, and be integrated with, the national development plan. They should analyse existing information or help collect needed nutritional information, and/or develop strategies or mechanisms to utilize research results in programme planning and implementation.

In Thailand, assistance from international agencies and collaboration with developed countries have facilitated the build-up of expertise in nutrition institutes in universities such as his own, Mahidol University. These university nutrition institutes (or departments) are a resource (1) to advise the ministries of Health and Agriculture on nutrition components of the national development plans and (2) to train community health professionals and agricultural extension workers to apply the newer knowledge of nutrition.

Dr. Dutra de Oliveira noted that, considering the large amounts of money and effort generously provided for training programmes in North America and Europe, it was his experience that in Latin America there are very few nutrition centres, very few local nutrition specialists, and correspondingly few nutritional interventions to help malnourished, poor people. There are some exceptions to this general statement, e.g. INCAP. What has happened to most of those from Latin America who have received advanced training in nutrition outside of the region? Why are they not working in nutrition science and programmes within Latin America?

He suggested six reasons:

• The young scientist has not been trained to work under the conditions predominating in a developing country.
• The developing country he/she returns to has a poor infrastructure for support of scientific endeavours.
• The local government has no job for the young scientist.
• Very few universities have nutrition courses, and therefore there are no lecturers' positions.
• Nutrition research institutes are practically non existent, so they offer no positions.
• Nutrition programmes, in general, are used as political weapons.

After a few years of struggling to adapt to conditions back home, most of the young, bright, well-trained nutrition workers give up nutrition and take a position in another field. Among hundreds of Latin Americans trained overseas in nutrition, only a few dozen are actually working in nutrition in their own countries. To overcome this deterrent to advancement of nutrition science in a country, there is great need for continued contact and support of trainees from the parent training institutions when they return to their home countries.

International organizations offer support for training personnel, for conducting intervention programmes, and for food and nutrition research, but with limited success. One reason, Dr. Dutra believes, is that, except for the United Nations University, international agencies deal only with government ministers and officials. In some countries in the region governments are transient; in others they are not very concerned about the problems of poor people. More effective programmes would be likely if international agencies supported those universities with expressed interests in nutrition and the few existing research institutes. These institutions could do much more work if provided with more international support. He urged that international funding for nutrition programmes should go to local universities or similar institutions rather than to governments.

When investigators from developed countries plan a collaborative project, their main objective is to collect data. Naturally, the training of local people and the establishment of a continuing nutrition centre have lower priority. For example, although there have been several collaborative projects with developed countries in north-eastern Brazil, this area remains an area for research in malnutrition. The researchers did not appear to have been interested in developing expertise among local groups.

Unfortunately, also, most international courses in industrialized countries have not adequately prepared trainees for work in Latin America or Africa. They have not developed the needed leadership qualities in their trainees. Alternative courses available within the region have not been adequately supported and recognized. The IUNS could perhaps assist with overcoming this problem.

It would be very helpful if experienced nutrition scientists from developed countries could be supported as visiting professors at institutions in Latin America for a specific length of time. Too often experts from international agencies stay for only a few days in large cities, where they talk to government officials. They are taken to a few chosen persons, but may not meet the people who do the work in nutrition. The experts' contribution to advancing nutrition science in the country, therefore, is limited.

Dr. Joseph Hautvast's first point was that all countries should have formulated nutritional objectives. In less-industrialized countries, these might be to reduce the number of wasted children or to reduce vitamin-A deficiency or iodine-deficiency disorders.

At the international level, targets are set for developing countries by the United Nations ACC/SCN (Administrative Committee on Co-ordination, Subcommittee on Nutrition), which is a focal point for co-ordinating activities for FAO, WHO, UNICEF, the United Nations University, Unesco, the World Bank, the World Food Programme, the World Food Council, the UN Environment Programme, and bilateral donor countries. The priorities of the ACC/ SCN include maternal nutrition, encouragement of breast-feeding, nutrition in primary health care, nutrition for low-income families, and a number of country projects in the developing countries. The ACC/SCN is a close family.

Dr. Hautvast commented that some reports, i.e. short books, were particularly useful for nutrition work in developing countries. He mentioned as examples the FAO/WHO/UNU Energy and Protein Requirements (1985); Cameron and Hofvander's Manual on Feeding Infants and Young Children (1983); Ooments Tropical Leaf Vegetables in Human Nutrition (1977); the World Bank's bock Malnourished Peoples; the FAO/WHO ninth joint expert report, Food and Nutrition Strategies in National Development (1976); the WHO and International Vitamin A Consultative Group (IVACG) report Vitamin A Deficiency (1982); and the International Nutritional Anaemia Consultative Group (INACG) Guidelines for Eradication of Iron Deficiency Anaemia (1977).

In every developing country a first priority should be to strengthen and increase the local manpower of scientists and professionals in human nutrition. Countries need a critical mass of these resource people. Since there are losses from time to time, the minimum effective number (six, twelve, or whatever is considered best) is never sufficient. There is need for institutional strengthening and human-resource development. For nutritionists, improvement in the quality of life is an objective. People are not instrumental means to development but rather the objects of development. These aims differ from those of business, of industry, and of economists.

Dr. Hautvast's institution, Wageningen University, in the Netherlands, is engaged in a number of cooperative projects. Funds for these have come from Sweden and from the Netherlands. The university has several different training courses, more now being conducted in less-industrialized countries than in the Netherlands. These courses are given in English. There is an international course at Wageningen that concentrates on food and nutrition planning and on maternal and child nutrition. Sixty per cent of the participants come from Africa. The university cooperates in courses given in the Philippines and Indonesia, is starting a training programme in Zimbabwe, and has held workshops in eastern and southern Africa. Two newer concepts in collaboration are under way: One is the production of books on regional nutrition - e.g. one on iodine-deficiency disorders in eastern and southern Africa, and another on child feeding in this region. The other is "South-South cooperation" - e.g. nutritionists from the Philippines helping Sri Lanka, with the Dutch serving only as technical support.

Networks can be useful, but Dr. Hautvast thinks they should be more than long lists of names and addresses. It is much better to have in-depth cooperation with a small number of institutions and to share money for training. One advantage of a small network with close institutional involvement is that trainers in one institution are familiar with the background that students come from and the type of work and conditions they will go back to in their own countries.

Sometimes it seems that international agencies are competing to establish training programmes rather than co-operating. Dr. Hautvast thought, for example, that the FAO should not carry out its own training programmes; universities are better equipped to be training agencies.

Finally, he observed that co-operation requires time, patience, friendship, and some "easy" money, i.e. flexible-use money.

He thought that the biggest challenge for the IUNS is to find ways to help Africa meet its needs for trained manpower in nutrition and for nutrition programmes.

Dr. James Olson opened his presentation by noting that developed countries sometimes feel, to those living in them, as if they are declining or disintegrating rather than continuing to develop. Developed countries and their people have their own distinct problems.

In co-operation between institutions in developed and developing countries the personal aspect is very important. Both sides need to care about some part of a project, and there must be ability on both sides. Dr. Olson's formula for successful intercultural cooperation was summarized by three nutritiona ssociated acronyms: MEAT, FISH, and OVOVEG. MEAT stands for the attributes of mutuality, equality, ability, tolerance; FISH represents focus, initiative, sincerity, helpfulness; and OVOVEG stands for organization, vitality, originality, vision, equanimity, and graciousness. These ingredients, carefully mixed and allowed to mature over time, provide a recipe for lasting, mutually satisfying working relationships.

In co-operative activities, education can be the catalyst, i.e. working with bright young people. The types of activities in nutrition where education can prevail are research projects or surveys, training courses or conferences, or planning exercises and development of policies. Projects can be limited in size, e.g. lecturing for six months, or of medium size (several years), or large and extending over a long period. The bigger the project, the more time required. In the first two years, you and your counterpart(s) are just beginning to relate to one another. Unfortunately, few agencies fund projects far enough in advance to allow the time needed for their completion. Dr. Olson noted a number of ambitious projects that were cut off by the granting agency after only four years - too soon to expect sustained, successful collaboration to have developed.

Dr. Olson suggested appropriate objectives for guest scientists planning to work in a developing country:

• to help able people and good programmer;
• to leave some lasting improvement (i.e. What can I leave here that will be useful?);
• to never forget one's guest status; one cannot be arrogant or as critical of the system as in one's own country, though sometimes one can gently raise an issue as an outsider; - to broaden one's perspectives.

Among the joys of working in another country may be that more varied problems are encountered and can be studied, and broader resources can be applied. Professional interaction can be rewarding, and the intercultural ties that emerge may be lasting. There is also the possibility of benefiting more people from one's work than would be possible if one stayed at home.

Against this, the personal limitations for scientists going from a developed country to work in a developing one may be the higher costs of research equipment and consumables and the probability of poorer funding. In addition, they are isolated from their own society and from what is happening on the frontiers of their science. Productivity is likely to decrease and career development to be slower.

Dr. Olson listed nine special concerns for a developed-country scientist working in a developing country:

• differing concepts of the university's role in society,
• inadequate instrumentation and maintenance of equipment,
• customs delays and costs,
• shortage of trained personnel,
• the necessity of undertaking multiple duties,
• the possibility that funding may be politically motivated,
• re-entry problems and the risk of brain-drain,
• a possible disparity between social needs and scientific orientation,
• personal safety (in some parts of the world).

At present the most needy developing or least-developed countries are in Africa and parts of Asia. Dr. Olson thought that international and bilateral agencies have over-focused on basic studies underlying applied programmes. More useful approaches might be support of a university nutrition programme or the survey-intervention-evaluation triad. Public education and policy change are much more difficult. What might be the role of the IUNS? He suggested support for conferences, training, and advisory work.

Points from the discussion

Speakers from developing countries spoke of the danger of visiting scientists coming with patronizing attitudes. Collaborative projects should aim for some social and economic payoffs within the country. India has stopped the export of blood samples for research analysis on the grounds that it is better for the equipment, method, and knew-how to be established in the country where the project is.

Foreign experts often do not take the time to understand the people or to become familiar with the extent of variations within the country. For example, people in developing countries would like to have healthy food habits but do not want to lose their traditions. It is very difficult to have the same food and nutrition policy nationwide. What is needed is to have more general guidelines that can be adapted to local circumstances.

On the subject of international courses, the chairman observed that students away from their own backgrounds often become less inhibited and more prepared to interchange with colleagues from other countries. Another speaker suggested that training should not be one-dimensional. There should be an exchange of students from developed to developing countries as well as in the more usual direction, and an exchange of teachers. The course in Uppsala will probably soon be given in English, like the international course in Holland, to facilitate student exchange.

Many scientists are deficient in programme management as well as in data management. Short courses on elementary management, financial management, and labour relations would be helpful, and basic computer courses would also be desirable.

There were several suggestions as to what the IUNS might do to help:

• Provide recognition of training courses in universities in developing countries. Develop curricula and set standards.
• Facilitate compilation of data about nutritional activities in the countries of the different adhering bodies.
• Encourage and facilitate exchanges of teachers in nutrition.
• Concentrate on building up nutritional expertise in Africa, e.g. support IUNS Working Group 11/3.
• Organize help for nutrition departments in developing countries with nutrition journals.
• Stimulate the recording of successful and unsuccessful nutrition programmes.

In addition, it was suggested that the IUNS should explore the potential for co-operation with food-related industries or other agencies on one or more of these desirable activities. The key to doing many of these things is finding money. There were good ideas discussed at this workshop that should appeal to industry or foundations for funding.

News and notes

Fifteenth session of the ACC Sub-committee on Nutrition

The Fifteenth session of the Sub-committee on Nutrition of the UN Administrative Committee on Co-ordination (ACC/SCN) was held in New York, 27 February-3 March 1989. The following is from the official report of the session.

Objectives for Fourth Development Decade and proposed international conference on nutrition

The ACC/SCN strongly strongly advocates that the Fourth Development Decade should focus on human development. Nutrition is a fundamental part of human well-being. Improving nutrition requires effective action in many sectors.

Malnutrition still affects perhaps one-third of the population of developing countries. More serious, in the 1980s trends in malnutrition prevalence are rising in many countries, in contrast to the 1970s. In most regions of the world, the number of malnourished children continues to increase with population growth.

Malnutrition is a central constraint in human development. It contributes to increased sickness and deaths, particularly in children, to lowered educational performance and to reduced productivity. Vitamin and mineral deficiencies cause blindness, mental retardation, and physical exhaustion. Malnutrition results from poverty, and can be overcome through the process of economic and social development in such areas as education, income, provision of health services, household food security, and others.

Better nutrition is a measure of progress and an important objective of development policies and programmes. Achievement of nutritional objectives will be a measure of the success of the Fourth Development Decade.

The ACC/SCN noted that malnutrition, including micronutrient deficiencies, can be reduced through vigorous and sustained efforts, as has been recently seen in some developing countries. Enough is now known, with available technology, to bring about a major change in the world nutrition situation, if there is adequate commitment and available resources. The UN system could be in the forefroont of a new drive for this goal.

The ACC/SCN recommends consideration of a major effort by governments, organizations of the UN system and bilateral agencies, including financial institutions, and non-governmental organizations, to:

• increase awareness of the magnitude, causes, and consequences of nutrition problems;
• formulate and adopt strategies, based on available knowledge and technology, to meet nutritional goals;
• mobilize resources for a concerted effort to implement these strategies;
• get momentum behind action for a human nutrition focus for the 1990s Development Decade.

For this purpose, the ACC/SCN proposes to the ACC that a broader dialogue should be initiated, through the mechanism of an international conference involving governments, organizations of the EN system including financial institutions, bilateral partners, non-governmental organizations, and others concerned, to address the above objectives.

Nutrition in times of disaster

The ACC/SCN noted with concern the prospect of continuing need for food relief for very large numbers of displaced people - who have lost access to productive resources - and the likelihood that this situation, which affects some 20 million people at present, will continue and probably worsen.

A conference on "Nutrition in Times of Disaster" was held under the auspices of the ACC/SCN and the International Nutrition Planners Forum, organized by WHO and UNHCR, 27-30 September 1988. The SCN endorsed the statement issued by the conference see page 64].

The SCN requests the ACC to bring this tragic situation urgently to the attention of donor governments.

The significance of small body size in populations

There is a debate about the concept of "small but healthy" concerning whether small body size is in itself significant for leading a normal life. The implications of this for policies could be far-reaching, because of the widespread failure to reach genetic potential among populations of developing countries. The SCN examined the issue and approved the following statement to the ACC.

"The human response to adverse conditions during early life is a slowing of normal physical growth and development. When this failure of growth occurs in early childhood, it can persist throughout life, as smaller stature and weight in comparison to values seen in unconstrained populations.

"It is the factors associated with the process of becoming small, not the state of being small, that are the real concern, albeit both are marked by achieved size. Although the small individual may be healthy at a particular time, the conditions that have caused this smallness are basic deprivations, including poor diet and ill-health, frequently due to poverty. The reason that economic disadvantages and poor social performance are observed to be associated with smallness is that these frequently occur in conditions where health and diet are poor. But the resultant smallness itself - with two exceptions noted below - is not a primary factor perpetuating these conditions. Small achieved body size is often an indicator that conditions have detrimentally affected human development and may be continuing to do so in the population.

"With two exceptions it is not considered that 'being small' - as opposed to becoming small - is in itself harmful to the individual. One exception lies in the relationship between body size (lean body mass) and maximal physical working capacity as well as perhaps the capacity for sustained work (endurance). The other exception lies in the linkage between maternal size and infant birth-weight - the intergenerational linkage of smallness and risk.

"Failure of growth in the individual may be symptom of an underlying diet or health problem warranting intervention. It can also be seen as a marker of a high-risk environment.

"Smallness seen at the population level is explicit evidence for a generalized public health problem calling for policies and programmes designed to alleviate social and economic deprivations, in addition to direct public health interventions."

The ACC/SCN proposes that this position be drawn to the attention of UN member agencies and other interested parties, to contribute to the correct interpretation of conditions in developing countries.

Nutrition in times of disaster

A conference on "Nutrition in Times of Disaster" was held at the headquarters of the World Health Organization, in Geneva, 27-30 September 1988, under the auspices of the UN ACC Sub-committee on Nutrition and the International Planners Forum (a group of senior nutrition planners and managers from developing countries), organized by the WHO and the Office of the UN High Commissioner for Refugees. The conference issued the following statement.

"In the last fifteen years, the continuing problem with famine and disasters, bath natural and manmade, has resulted in unprecedented numbers of people depending for survival upon international food aid, sometimes for prolonged periods of time. The generosity of donor nations has been immense, but, even so, the total volume of emergency resources (food and money), provided bilaterally or multilaterally through organizations such as the World Food Programme, has proved painfully inadequate to meet escalating needs. The food provided has also, at times, failed to reach intended beneficiaries due to severe logistical and security constraints in recipient countries.

"Consequently, the rations provided very often result in a seriously insufficient and unbalanced diet.

"The food shortages, along with other factors, have often had a dramatic effect, increasing disease and deaths among affected populations, particularly in refugee camps. In this context, there are alarming reports of outbreaks of certain nutritional deficiency diseases which have hitherto been considered to be under control, such as such as scurvy, severe anaemia, and beriberi. These outbreaks may, in a large measure, be ascribed to an inadequate quantity and quality of the food available locally and/or provided by international assistance.

"The participants in this conference consider that a minimal standard for food provision for emergency conditions must be maintained. This requires the provision of at the very least 1,900 kcal per person in the daily diet. Furthermore, such a standard diet should contain all essential nutrients at levels that have been determined necessary to maintain health and sustain life.

"The conference urges the populations of donor nations and their Governments to assist the UN family in meeting these goals. Specifically, it urges donor nations to increase their emergency resource allocations and to programme these according to estimates of emergency needs rather than reacting to each situation in an ad hoc manner. It urges that more of this emergency food aid be channelled through multilateral agencies. In order that nutritional standards can be met, it further urges donor nations to diversify the composition of food aid that they provide without reducing the total amount of calories allocated. Finally, it encourages both affected countries and the donor community to intensify efforts to strengthen the capacity of governments to cope with their own disasters and assure the provision of a nutritionally adequate diet to disaster-stricken populations.

"The meeting urges donor nations to assist the UN family in meeting these goals. Such actions are of the greatest urgency if this toll of lives is to be reduced."

For further information, please contact Dr. John B. Mason, Technical Secretary, ACC/SCN, Office No. X-SO, WHO Headquarters, CH-1211 Geneva, Switzerland, telephone (22) 91 33 23; Dr. Abraham Horwitz, Chairman, ACC/SCN, Pan American Health Organization, 525 Twenty-third Street NW, Washington, D.C. 20037, USA, telephone (202) 8163181; Dr. John Rivers, Department of Human Nutrition, London School of Hygiene and Tropical Medicine, Keppell Street, London WC1E 7HT, UK, telephone (01) 636-8636.

International Dietary Energy Consultancy Group.

The International Dietary Energy Consultancy Group (IDECG) was established in Geneva on 3 September 1986, under the sponsorship of the United Nations University (UNU) and the International Union of Nutritional Sciences (IUNS) and with the endorsement of the ACC Sub-committee on Nutrition (ACC/ SCN) of the United Nations.

Aims and objectives of IDECG

IDECG has been established for the study of dietary energy intake in relation to the health and welfare of individuals and societies. Its specific objectives, as defined at the foundation meeting in Geneva, are:

(1) The compilation and interpretation of relevant research data on functional and other consequences of deficiency, change or excess of dietary energy.

(2) The identification of related research needs and priorities and the promotion of needed research.

(3) The publication of scientific and policy statements and other information on the significance of chronic deficiencies and excesses of dietary energy.

(4) The identification and promotion of appropriate and practical means of corrective action.

To meet these objectives, IDECG seeks to bring together scientists engaged in relevant research with representatives of international organizations concerned with the problem. It also seeks to involve in its work bilateral agencies, foundations, and governments interested in relevant research and policy actions.

A process is needed to continually adapt the interpretation and operationalization of the organization's objectives to what its potential users and contributors perceive to be their most important and most pressing needs. On request of the steering committee, this process has been initiated by Prof. George Beaton, who has canvassed a broader group of interested individuals for this purpose. From the responses received it is apparent that there is a dichotomy of views about priorities: while some emphasize the need to move ahead and offer advice on current issues related to policy formulation and implementation, others hold reservations about the reliability of available knowledge on which such advice would be based. Prof. Beaton attempts to reconcile the two views and concludes:

It is clear, then that IDECG must accept the reality of a duality of function and embody this within its short-term and long-term goals. It is recognized that, at times, the duality will create apparent conflict and will certainly compete for available resources. That IDECG must accept. There is not a true duality - there are two dimensions of a single purpose - to improve our understanding of the relationship of energy intake to human function and through this understanding to promote policies and activities that may operate for the betterment of human health and well-being.

Organization of IDECG

IDECG is sponsored by the UNU, with the endorsement of the ACC/SCN, and by the IUNS. UNU responsibility for the policies of IDECG is delegated to a steering committee, consisting of a representative of the UNU as chairperson, the secretary general of the IUNS, and the executive secretary of IDECG. Responsibility for the administration of IDECG is delegated to the executive secretary.

The steering committee is guided by an advisory group consisting of nine scientists, appointed for staggered three-year terms, and a representative each from FAO, WHO, UNICEF, and the World Bank. Additional persons may be invited to participate in the advisory group, in meetings, and in other activities of IDECG as needed for scientific or policy reasons.

First scientific IDECG meeting on chronic energy deficiency

Thirty scientists from 15 countries met in Guatemala City in August 1987 for the first scientific meeting of IDECG. The focus of the meeting was on chronic energy deficiency and its effects on behavioural development, stature, work capacity, and productivity. Papers were also presented on the socio-economic consequences of and responses to food deprivation, seasonality in energy metabolism, the effect of energy supplementation, research on metabolic adaptation to low energy intake, and maternal energy requirements. This information was supplemented by reports on studies carried out in Colombia, Egypt, Ethiopia, Gambia, Guatemala, India, Indonesia, Mexico, and the Philippines. Participants later prepared reports on available knowledge, policy implications, and research needs and priorities. State-of-the-art papers and working-group reports were published in a book entitled Chronic Energy Deficiency: Consequences and Related Issues, which is available from the IDECG secretariat free of charge.

Definition of chronic energy deficiency

The presentations and discussions at the Guatemala meeting made very apparent that the term "chronic energy deficiency" has been defined and used in many different ways. Several participants expressed their dissatisfaction with this state of affairs and recommended that "chronic energy deficiency," certainly an important concept in connection with IDECG's preoccupations, should be better defined and used more consistently. The steering committee of IDECG decided to follow this suggestion by appointing a small working group and charging it with the development of a set of recommendations on the operational definition and use of the term "chronic energy deficiency."

This working group, consisting of Professors J. C. Waterlow, A. Ferro-Luzzi, and W. P. T. James, met twice and elaborated a report on the definition of chronic energy deficiency (CED) in adults which has been published in the European Journal of Clinical Nutrition (vol. 42, pp. 969-81). In essence, it recommends defining chronic energy deficiency in adults as a steady state which can be maintained, but at a level at which certain functions and/or health are impaired. A progressively more precise approach to identifying chronically energy-deficient adults involves measuring body weight and height, then energy intake (or expenditure), and finally the basal metabolic rate (BMR). Three cut-off points for body mass index (BMI) = weight/height²) were identified: 18.5, 17.0, and 16.0. Adults with a BMI above 18.5 are to be classified as normal, and adults with a BMI below 16.0 as suffering from grade III CED. A diagnosis of grades I and II CED depends on finding the combination of a BMI of 17.0-18.4 or 16.0-16.9 with a ratio of energy turnover to predicted BMR of less than 1.4. Measuring the individual BMR avoids classification and confirms the diagnosis. These guidelines can be used when assessing the input of aid programmes and for clinical and other studies.

Standardization of the doubly-labeled water method

The study of whole-body energy metabolism in humans requires information on dietary energy intake, energy expenditure, and the body's energy stores. Although it is possible to measure energy intake and expenditure very precisely, this can only be achieved by restricting subjects to a whole-body respiration chamber, measuring the energy content of their preselected diets and correcting for faecal and urinary losses. Unfortunately the techniques available for making such measurements in people living their normal lives have hitherto been very imprecise, and it is a general rule that the less a given measurement interferes with a subject's life-style, the less reliance can be attached to the data. This imprecision, together with probable in-built biases in the methods for measuring energy intake and expenditure, has led to a situation where estimates of energy expenditure almost always substantially exceed estimates of energy intake when both are measured simultaneously. As a result of these uncertainties, nutritionists are still unable to answer some of the most fundamental questions relating to man's energy requirements.

It has been argued that greater reliance should be placed on dietary intake data, on the grounds that it is easier to accurately quantify energy intake, which occurs relatively infrequently during the day, since the technical problems associated with weighing food and calculating its energy content are relatively minor. The counter-argument, however, is that such measurements are subject to an "observer effect" and that people consciously or subconsciously alter their eating patterns when they are recording their dietary intake. Many scientists therefore remain sceptical about the very low energy intakes reported for underprivileged people in the developing world and in such groups of people as the obese, in whom there may be a strong motive for concealing true intake. Measurement of total daily energy expenditure on the other hand is inevitably complex, since energy is expended throughout the day at a level which can vary over a tenfold range from minute to minute. Attempts have been made to integrate these variations by a "factorial method" in order to quantify total daily energy expenditure in free-living people. For this method, subjects are observed, or asked to record an accurate diary of their activities, throughout the period of study. The time-and-motion data recorded in this way are converted to energy expenditure using standard tables for the energetic cost of each type of activity, or using average data collected in the specific population being studied. Even when performed by the most competent technicians, such a method will inevitably be associated with a high level of imprecision, and there are theoretical reasons why it is most likely to overestimate energy expenditure.

There is, therefore, a need for the development of an accurate and non-intrusive method for measuring energy expenditure in free-living people, and the doubly-labelled water (DLW) method is rapidly becoming established for doing just that. It is based on calculations taking account of how the body metabolizes hydrogen and oxygen. At the beginning of the measurement period, the subject drinks a glass of water enriched with two stable isotopes (²H₂¹⁸O). The hydrogen isotope deuterium (²H) equilibrates throughout the body's water pool, and the oxygen isotope (¹⁸O) equilibrates in both the water and the bicarbonate pool, which consists largely of dissolved carbon dioxide in the blood stream that is the end product of metabolism and passes to the lungs for excretion. The rate constants for the disappearance of the two isotopes from the body are measured by mass spectrometric analysis of a series of samples of urine, saliva, or blood.

In July 1987, the British Nutrition Society hosted a symposium on "Stable Isotopic Methods for Measuring Energy Expenditure," at which all laboratories actively involved in DLW studies in humans were represented. The meeting left little doubt about the great potential of this new method, but no consensus could be reached yet on two important issues: the best method of calculating energy expenditure from isotope disappearance curves and the best way of dealing with isotopic fractionation.

At the IDECG meeting of 3-7 August 1987 in Guatemala City, Dr. Prentice, from the Dunn Nutrition Laboratory in Cambridge, England, proposed to organize a workshop for the standardization of the DLW method. IDECG decided to support this initiative, and the Nestlé Foundation agreed to fund the workshop, which took place in Cambridge 26-29 September 1988.

All the eight research centres using the method in humans and two which have done pioneering work in animals were represented at the Cambridge workshop. Data sets and position papers on various aspects of the method were exchanged among centres prior to the meeting. The main issues presented and discussed at the workshop were isotopic pool sizes and flux rates, estimates of error, fractionation effects, isotope exchange, effects of changes in isotopic background, the energy equivalent of CO₂, problems of mass spectrometry, and problems arising when the method is used in special groups of humans like premature babies and certain categories of hospitalized patients.

The discussion was very open, and consensus could be reached on all important issues.

It is planned to publish the conclusions reached by the workshop participants in two formats: firstly, as a detailed and comprehensive technical report for users of the method, and secondly, in the form of a shorter, more general paper for persons who need to be able to correctly interpret data obtained by the DLW method.

Energy requirements of infants and children

The next IDECG meeting will take place late this year to review the energy requirements of infants and children, considering all the new information which has become available since the latest edition of FAO/ WHO/UNU recommendations was published in 1985.

Conceptually a new feature of that report was that, for adults, it based energy requirements on energy expenditure, including energy expenditure for physical activity as an important factor to be considered. At that time it was not possible to adopt the same position in the formulation of energy requirements for infants and children. Because the necessary information on energy expenditure in that age group was not yet available, energy requirements continued to be based on information on energy intakes of infants and children growing normally. Thanks to the development of the doubly-labelled water method and renewed interest in that area, a considerable amount of new information has become available on children's energy expenditure, so that it appears useful and timely to reanalyse the energy requirements of infants and children from that new perspective.

For further information, write to: Dr. B. Schurch, Executive Secretary, IDECG, c/o Nestlé Foundation, PO Box 518, 1001 Lausanne, Switzerland.

Codex Committee on Vegetable Proteins: Vegetable protein production.

The fifth, and probably last, session of the Codex Committee on Vegetable Proteins was held in Ottawa, Canada, 6-10 February 1989, and was attended by 40 representatives and observers from 14 countries. The committee has now proposed guidelines for the utilization of vegetable protein products in foods and international general standards for such products and for soy protein products and for wheat gluten. These documents will now be treated by the Codex Commission at its meeting in Geneva in July 1989.

Dr. Walter Wolf of the US Northern Regional Research Centre in Peoria, Illinois, presented a review on current international trends in the production and utilization of processed vegetable proteins. The following are some excerpts from his report.

Development of new vegetable protein products and spectacular growth of markets that were forecast in the past 20 years have not occurred. Nonetheless, progress has been made in specific areas.

Soybeans

The United States soybean processing industry is the acknowledged leader in the development of edible proteins from soybeans. Flours, concentrates, and isolates have been commercially available for 30 years or longer and are no longer considered new or navel. At present, soybean proteins and wheat gluten are the only significant vegetable proteins available commercially. Others are used on only a small scale (e.g. peanut and pea) or are still in the development stage (e.g. glandless cottonseed and sweet lupine). There was a rapid growth in traditional Oriental soybean foods, particularly tofu, miso, and tempeh, beginning in the late 1970s. Soymilk has been slower to attract the attention of Western consumers than was tofu.

Although soybean proteins are well established, concerns have remained about certain nutritional aspects of their use. In the past decade nutritional studies have focused on four major areas: the effects of trypsin inhibitors on the pancreas, adequacy of methionine in soybean proteins for human diets, the effects of soybean proteins on the bioavailability of dietary iron, and the cholesterol-lowering effects of soybean proteins.

Trypsin inhibitors are widely distributed in nature, and consequently they occur in many common food items such as the legumes, cereal grains, potatoes, and eggs. Because normal moist-heat processing inactivates most of the soybean trypsin-inhibitor activity, many experts agree that properly processed soybean protein products do not pose a hazard to human health at practical levels of consumption.

It is well known that methionine is the first limiting amino acid in soybeans as determined by rat assays. Recent studies show that, for humans, the limitation of methionine is not as serious as formerly believed and depends on the age of the subjects. Based on these studies, it was concluded that when the isolates are consumed as the sole source of dietary protein, at a level of 0.8 g of protein per kilogram of body weight, protein nutritional status can be maintained adequately. The methionine content of soy proteins appears adequate to meet the nutritional needs of preschool children and adults, but there may be a need to supplement soy-isolate-based formulas for infants. In the early 1980s several research groups reported that addition of soybean protein products to experimental diets depressed absorption of dietary iron. An extensive study was therefore designed to test the long-term (six months) effects of extending beef with soybean protein in men, women, and children under practical conditions. Results indicated that soybean protein at the levels used does not impose a risk of iron deficiency.

Studies with experimental animals and humans have shown that dietary protein can influence the level of cholesterol in the blood. For example, feeding of casein in a cholesterol-free diet to rabbits causes hypercholesterolaemia, and on continued feeding artherosclerosis develops, but these effects are prevented when soy protein replaces the casein. The mechanism by which say protein lowers blood plasma cholesterol is unknown but is under active investigation in a number of laboratories.

Cottonseed

In order to circumvent the problems of gossypol, research and development has proceeded with glandless varieties of cotton. In 1986 Yazaki, in the United States, introduced defatted flours made from glandless seeds and began market development for the flours in foods. In early 1988, however, the company ceased its cottonseed protein operations, and at the present there are no edible cottonseed protein products produced in the United States.

Lupines

Newcomers to the vegetable protein field are the sweet lupines, which are low-alkaloid strains of several Lupinus species. Development work on lupine proteins has been conducted particularly in countries where soybeans are not grown,

Sunflower

Pilot-plant quantities of sunflower-seed flour, protein concentrates, and isolates have been available in the United States, Italy, and Canada in recent years. Difficulties in decortication and colours caused by chlorogenic acid continue to be problems limiting development.

Wheat gluten

Wheat gluten is the water-insoluble protein portion of the grain endosperm. Manufacture of wheat gluten involves separation of the protein and starch fractions of wheat flour. Its major use is in bakery products to increase protein content, thereby obtaining dough strength, mixing tolerance, and handling properties. In Europe gluten has found extensive use to fortify low-protein wheats from Canada, the United States, and Australia. Up to 1% gluten is routinely added to bread-making flours in France. Other applications include meat, poultry, and fish products where the adhesive, and film-forming properties are used.

Rapeseed

Appreciable progress has been made to improve the composition of rapeseed. New low-erucic, low-glucosinolate varieties are collectively known as Canola to differentiate them from the older, higherucic type rapeseed. The much reduced levels of glucosinolates in Canola varieties (up to 30 micromoles of glucosinolates per gram of dry, oil-free meal) are still considered too high for incorporation of the meals into food products. Rapeseed meals also contain various phenolic compounds dominated by sinapine which taste bitter and cause discolouration by reaction with other components. Two major obstacles to the commercial production of edible protein concentrate from rapeseed are the lack of efficient methods for dehulling and for reducing the content of phytate to acceptable limits. The economics of preparing rapeseed protein concentrate are not very favourable in spite of the fact that rapeseed protein is of outstanding nutritional quality. No commercial preparations of rapeseed protein fractions are presently produced.

Peas

Processes for production of pea flour and pea protein concentrates have been developed in Canada. The concentrates contain 83%-85% protein and are being used in the baking industry as replacers for nonfat dry milk and as protein supplements.

Other legumes

A number of legumes, including chickpeas, pigeonpeas, common dry beans, Phaseolus vulgaris, and black gram supply a substantial amount of dietary protein, especially to residents of rural Africa and Asia. They are prepared for consumption in a number of ways, including cooking of whole and dehulled seeds, fermenting, germinating, and grinding into flours and meals. They are generally high in carbohydrates (mainly starch) and low in fat. Consequently, even defatted flours are low in protein compared to the minimum of 40% specified in the standard for vegetable protein product. Protein concentrates and isolates have been made experimentally from many of them, but there is no large-scale commercial processing. Faba bean protein isolate was manufactured and used commercially for time in the United Kingdom to produce a spun fibre but was discontinued because the economics were unfavourable. In France, commercial production of air-classified faba bean protein concentrate and starch is reported.

Leaf proteins

A number of countries have conducted extensive research and development work on the recovery of proteins from green leaves, which are the world's largest supply of protein. Because of the high fibre content of leaves, the proteins must be separated from the fibre and concentrated. At present there is no commercial production of edible-grade leaf protein, and near-term prospects for establishing an industry are not encouraging.

Single-cell proteins

Dried cells of micro-organisms such as algae, actinomycetes, bacteria, yeasts, moulds, and higher fungi are included in the category commonly referred to as single-cell proteins (SCP). In technologically developed countries much work has been expended in this field, but at present these products are still minor sources of protein for humans. SCP is used primarily for animal-feed supplements, and in some countries SCP has not been able to compete even as a feedstuff because of cheaper sources of protein, such as soybean meal. Near-term prospects for these products do not look very promising. Yeasts, for example, which have a long history of consumption and acceptance as food, are too expensive to compete with soy proteins as a source of protein but are utilized primarily as flavouring agents. High contents of nucleic acids further limit utilization of yeasts as protein ingredients in foods.

Dr. Wolf's report ends with a review of present market potential and trends, and summarizes regulatory provisions and practices in 26 countries.

Courses offered

The International Training Division of the Nutrition Center of the Philippines, an associated institution of the United Nations University, is offering the following training courses in 1989 and 1990:

• "Planning and Management of Food and Nutrition Programs," scheduled for three months twice a year, March-June and August-November 1989 and 1990.
• "Community Management of Micro-nutrient Interventions (Vitamin-A Deficiency, Iron-Deficiency Anemia, and lodine-Deficiency Disorders) in Primary Health Care," scheduled for three months, January-April 1990.
• "Strengthening of Maternal and Child Health Nutrition in Primary Health Care," scheduled for six weeks once a year, November-December 1989 and 1990. - "Strengthening the School Health and Nutrition Program through a Teacher-Child-Parent Relay System Approach," scheduled for three months on the basis of country-level requests.

Each course consists of five components: (1) teaching sessions on core subjects relevant to the course, (2) field visit and observation of on-going programmes and projects, (3) village field practicum in selected communities, (4) written and oral technical report on training activities, and (5) home-country project development for the participant's re-entry plan.

The medium of instruction is English. Participants must have adequate knowledge of the language for effective participation in the programme.

All correspondence regarding nomination and registration may be addressed to: The Director, Nutrition Center of the Philippines, MCC P.O. Box 653, Makati, Metro Manila, Philippines 1299; cable: NUTRICEN, Manila.

IFPRI report

Consequences of deforestation for moments time allocation, agricultural production, and nutrition in hill areas of Nepal. Shubh K. Kumar and David Hotchkiss. Research report 69. International Food Policy Research Institute, Washington, D.C., USA, 1988.

Although estimates vary widely, most sources agree that 20% to 50% of the forests in the hill areas of Nepal, where agriculture has not benefited from improvements in technology, were cut down in the 1970s. In this report, the authors deal with the development issues facing a relatively poor agricultural area, and the interaction of low agricultural productivity with deforestation in promoting further deterioration in bath.

Deforestation, which stems primarily from the need to expand the area cultivated due to low agricultural productivity, is itself found to contribute directly to declining agricultural productivity via a reduction in household labour, especially moments. This reduction can be traced to the higher labour requirement for collecting fuelwood and other forest products, such as leaf fodder and grass for animals, and is not compensated for by an increase in wage labour. Since outmigration is already high - with one permanent migrant worker in every two households - local solutions are clearly required. Reforestation efforts could assist in rehabilitating existing forests but may not stem the pressure to clear new land.

Strategies for raising agricultural productivity, particularly focusing on the higher agricultural potential of the valleys, where lowland crops such as paddy and wheat are grown, should be a useful approach for stemming the pressure to expand the cultivated area in the hills. Current yields for these crops are very low. There is much scope for improvement with the use of improved varieties and fertilizer, which are now virtually absent. Such crop intensification in the lowlands should improve the area's market integration and make it easier to diversify into increased horticulture production, for which the region is ecologically well suited.

Livestock production is an important enterprise in the hill areas. Increased emphasis on rice and wheat could help to meet the fodder requirements, as straw from both these crops is used for cattle feed. This could reduce the need to collect grass and leaf fodder, easing both household labour constraints and the pressure on forests.

The study also highlights the significance of saving moments labour in improving household welfare. Technologies to save labour and enhance its productivity could include, for example, easier access to food-processing mills or improvements in water supply to reduce the carrying of water up and down hillsides. Forestry programmes that improve access to fuelwood and other essential forest products could also be highly complementary to an agricultural intensification effort that requires increased labour output.

Books received

Nitrosamines: Toxicology and microbiology. Edited by M. 1. Hill. Ellis Horwood Series in Food Science and Technology. VCH Verlagsgesellschaft, Weinheim, FRG; Basel, Switzerland; Cambridge, UK; New York, 1988. 169 pages, 20 figures, 25 tables. DM 180; £64.

This book discusses the analysis of volatile Nnitrosamines, their toxicology in animals or in vitro assay systems, and the evidence implicating N-nitroso compounds in human cancer. A final chapter is concerned with prospects for the future.

Statistical exercises in nutrition. Erica F. Wheeler. London School of Hygiene and Tropical Medicine, University of London, London, 1989. £6.

This set of examples of the application of biostatistics to community-based nutrition research, developed for students in the M.Sc. course in human nutrition at the London School of Hygiene and Tropical Medicine, can be used with any introductory course or text in biostatistics. It provides examples for all the methods appropriate to a beginning course in health biostatistics, taken from common and relevant problems of data analysis that are encountered in human-nutrition research.

Problems of endemic goitre in Gangetic belt: Possible measures to control. I). K. Agarwal, S. Srivastava, K. N. Agarwal, and 1. K. Agarwal. Nutrition Section, Department of Paediatrics, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India. Rs 35.

This 52-page pamphlet describes the apparently successful use of potassium iodate solution for addition to water consumed within the household. This would be a practical alternative to iodinated salt in populations too remote to be reached by iodized salt.

Note for contributors

The editors of the Food and Nutrition Bulletin welcome contributions of relevance to its concerns (see the statement of editorial policy on the inside of the front cover). Submission of an article does not guarantee publication-which depends on the judgement of the editors as to its relevance,and quality. Contributors should review recent issues of the Bulletin for content and style.

Language. Contributions may be in English, French, or Spanish. If French or Spanish is used, the author should submit an abstract in English if possible.

Format. Contributions should be typed, double spaced, with ample margins.

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References. References should be listed at the end of the article, numbered in the order of their appearance in the article, also double-spaced. A reference to a book or other separately published work should include full indication of the name(s) of the author(s), title of the work, and publisher and place and year of publication. A reference to an article in a book should include the name(s3 of the author(s) of the article, title of the article, editor(s) of the book and title of the book, publisher and place and year of publication, and the page numbers of the article. A reference to an article in a journal should include the author(s), title of the article, name of journal, volume and issue number and date, and page numbers of the article. Unpublished material should not be listed in the references.

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Contributions should be addressed to:

The Editor Food and Nutrition Bulletin 9 Bow Street Cambridge, MA 02138, USA

Note a l'intention des auteurs

La rédaction du Food and Nutrition Bulletin recherche des articles traitant de sujets correspondant a ses themes (voir au vérso de la couverture la politique éditoriale de cette revue). La remise d'un manuscrit ne signifie pas sa publication, qui dépend de l'opinion de la rédaction sur son intéret et sa qualité. Les auteurs sont invités a se pencher sur les récents numéros du Bulletin pour prendre connaissance de son contenu et de son style.

Langues: Les manuscrits peuvent étre rédigés en anglais, en français ou en espagnol, et dans ces deux derniers cas, I'auteur ajoutera, si possible, un résumé en anglais.

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Les auteurs s'adresseront a: The Editor Food and Nutrition Bulletin 9 Bow Street Cambridge, MA 02138, USA

Nota para los posibles autores

Los editores del Food and Nutrition Bulletin agradecen el envío de contribuciones pertinentes al tema de la revista (vea la política editorial de esta revista en el interior de la tapa anterior). La presentación de un artículo no es garantía de su publicación, la cual dependerá del criterio de los editores en lo que respecta a su pertinencia y calidad. Se ruega a los que deseen colaborar que consulten los números recientes de Food and Nutrition Bulletin para cerciorarse de su contenido y estilo.

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Referencias. Al final del artículo deberán consignarse las referencias, numeradas por orden de aparición en el articulo, también en doble espacio. La referencia a un libro u obra publicada deberá incluir indicación completa del nombre del autor o autores, título del trabajo, editorial y lugar y fecha de publicación. La referencia a un artículo de un libro deberá comprender el nombre del autor o autores del artículo, el título del mismo, editores del libro y título del mismo, editorial, lugar y fecha de publicación, y numeración de las páginas del artículo. La referencia a un articulo de una revista comprenderá nombres del autor o autores, título del artículo, nombre de la publicación, volumen, número y fecha, así como la numeración de las páginas del artículo. El material sin publicar no debe incluirse en las referencias.

Identificación. Los autores deberán consignar su nombre completo y la institución en que cumplen funciones. Si el material del artículo ha sido presentado previamente o se prevé su publicación en otra parte, en forma igual o modificada, se deberá agregar una nota con detalles sobre dicha publicación.

Copias de la contribución. El contribuyente deberá conservar una copia del material que envíe. No se devolverán los manuscritos a no ser que se pida su devolución.

Las contribuciones deberán dirigirse a: The Editor Food and Nutrition Bulletin 9 Bow Street Cambridge, MA 02138, USA

Recent and Forthcoming UNU Publications on Food and Nutrition

Identification of Food Components for INFOODS Data Interchange

by John C Klensin, Diane Feskanich, Victor Lin, A. Stewart Truswell, and David A.T. Southgate

Intended to help remedy the glaring incompleteness or inaccessibility in many parts of the world of data on the nutrient composition of foods, this book makes available for the first time a comprehensive standardization of nomenclature for international nutrient data exchange. It provides a straightforward set of rules for identifying food components precisely and constructing data bases suitable for transfer between computers.

WHTR-14/UNUP-734 ISBN 92 BOB-0734-x112 pages, 16.4x 23.9 cm, paper bound, US$20

Food Composition Data: A User's Perspective

Edited by William M. Rand, Carol T. Windham, Bonita W. Wyse, and Vernon R. Young

Knowledge of the composition of the foods eaten around the world is of critical importance for research and policy in public health, dietetics, and nutrition. Data on food composition, however, are extremely inadequate. This volume, examining the current problems of the field and what is needed to improve the situation, provides an essential introduction and survey of the subject for anyone who will be involved in gathering compiling, or using food composition data. It will be a useful reference for university courses on food and nutrition.

WHTR-10/UNUP-633 ISBN 92-BOB-0633-5 240 pages, 16.4x23.9cm,paper-bound, US$20

Research Methods in Nutritional Anthropology

Edited by Gretel H. Pelto, Pertti J. Pelto, and Ellen Messer

A comprehensive manual of anthropological methodologies applicable to field studies in nutrition this volume describes strategies of field research in nutritional anthropology, determinants and cultural components of food intake, methods for collecting and analysing data on energy expenditures, and statistical methods for nutritional anthropology.

WHTR-9/UNUP-632 ISBN 9-808- 0632-7 218 pages, 16.4 x 23.9 cm, paper-bound, US$30

Positive Deviance in Child Nutrition - With Emphasis on Psychosocial and Behavioural Aspects and Implications for Development

by Marian Zeitlin, Hossein Ghassemi, and Mohamed Mansour

Children who grow and develop well in environments where most children suffer malnutrition and chronic illness provide valuable examples to guide the design of programmes aimed at the malnourished. The book examines successful interactions between care-giver and child and the social support systems that sustain them and offers goals and guidance for future research.

WHTR-12/UNUP-697 ISBN 92-BOB-0697-1 16.4 x 23.9 cm, paper bound, US$30

Methods for the Evaluation of the Impact of Food and Nutrition Programmes

Edited by David E Sahn, Richard Lockwood, and Nevin S. Scrimshaw

This state-of-the-art discussion of methods for evaluating food and nutrition programmes focuses primarily on determining specific nutritional impact even in circumstances where adequate baseline data are not available. It recognizes also that food and nutrition programmes can have beneficial effects going beyond traditional health impacts and gives specific attention to social, economic, behavioural, and political consequences that may accompany a feeding programme.

WHTR-6/UNUP-473 ISBN 92-808-0473-1 291 pages, 16.5 x 23.5 cm, paper-bound, US$25

Effective Communications for Nutrition in Primary Health Care

Edited by Jean E Andersen and Aree Valyasevi

Concentrating on the experiences of developing countries, this book advocates the effective communication of nutrition and health information as a key component of primary health care. It provides a framework for evaluating nutrition communications needs, methodological guidelines, and suggestions for programme evaluation.

WHTR- 11/UNUP-634 ISBN 92-808-0634-3 220 pages, 16.4 x 23.9 cm, paper-board, US$20

How to Order Publications

A complete list of UNU publications is available from the University. Publications may be ordered by writing to: The United Nations University, FNB/SU, Toho Seimei Building, 15-1 Shibuya 2-chome, Shibuya-ku, Tokyo 150, Japan.

Microform Publishing: All UNU publications can be obtained on microfiche.