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close this bookFood and Nutrition Bulletin Volume 17, Number 3, 1996 (UNU Food and Nutrition Bulletin, 1996, 104 pages)
View the documentEditorial policy
close this folderProtein and amino acid requirements
close this folderHuman protein requirements: A brief update
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close this folderHuman amino acid requirements: A re-evaluation
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View the documentThe problem
View the documentNew approaches and tentative new amino acid requirement values
View the documentRecent 24-hour tracer studies of amino acid requirements
View the documentEstimates of the lysine requirement in adults
View the documentNutritional quality of wheat protein in adults
View the documentWorldwide applicability of estimates of indispensable amino acid requirements
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close this folderWorld essential amino acid supply with special attention to South-East Asia
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View the documentDietary evaluation: World regions and countries
View the documentOverall variability in data from 101 dietary calculations
View the documentRelations among diet, wealth, and health in 122 countries
View the documentChanges in food and essential amino acid availability from 1961 to 1992
View the documentAmino acid composition of food groups
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close this folderNutrition and behaviour
close this folderRapid assessment procedures for the health and nutritional profile of adolescent girls: An exploratory study
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close this folderMothers' knowledge, understanding, and use of the bubble chart in a rural area of central Mexico
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close this folderEffects of breakfast on classroom behaviour in rural Jamaican schoolchildren
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close this folderPublic health nutrition
close this folderSalt iodine variation within an extended Guatemalan community: The failure of intuitive assumptions
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close this folderCan Africa meet the goal of eliminating iodine-deficiency disorders by the year 2000?
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View the documentStatus of salt iodation programmes in Africa as of February 1996
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View the documentSustaining elimination beyond the year 2000
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close this folderVitamin A deficiency and the prevalence of xerophthalmia in southern Rwanda
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close this folderFood science
close this folderChemical composition and nutritive value of some wild-gathered tropical plant seeds
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View the documentTitle of interest - Food Habits in Later Life: A Cross Cultural Study

Conclusions and implications for nutrition policies and food programmes

Despite the economic, social, and human dimensions of protein-energy malnutrition in large areas of the developing world, current knowledge about the quantitative needs both for dietary energy and for the indispensable amino acids that are supplied by our food protein remains inadequate. In 1973 a group of senior investigators in the United Kingdom asked the rhetorical question "How much food does a man require?" [71]. Since that time, there has been a considerable amount of research on this topic. This follow-on effort has been facilitated by the development in a number of countries, including the United States, of whole-body calorimeters and by the application of the doubly labelled water technique, which permits a non-invasive, quantitative measure of energy expenditure in free-living individuals [72-75]. Hence, the energy requirements of individuals of all ages, from infants [76, 77] to the elderly [78], are now being refined and the database is being expanded. With reference to the requirements for indispensable amino acids, equivalent advances in technique have been slower to occur, and therefore their application has also been less extensive to date, in comparison with the explosion of studies involving use of the doubly labelled water method. However, it is encouraging to note that the application of amino acid kinetics and, by extension, the 13C-tracer balance method represents one of the most important developments in recent years with respect to the study of human amino acid requirements [28].

Based on these tracer-derived data, it is our view that the new, tentative requirements for indispensable amino acids represent the best available approximations of the needs for these nutrients in adults. Hence, we recommend that they be used as a rational basis for the formulation of amino acid mixtures, or of protein sources, intended for meeting the nutritional support of individuals in institutional settings; the determination of the composition of enteral products is a case in point. Furthermore, these newly proposed values for the amino acid requirements of adults serve, in our view, as a credible benchmark for assessing the quantitative impact of disease and trauma on amino acid requirements. They should aid, therefore, in the design of parenteral nutritional formulations and, hopefully, lead to improvements in their efficacy for supporting the nutritional and metabolic needs of patients in a catabolic state.

Finally, as pointed out above, the revised requirements for adults are similar to those of young children when expressed in relation to the need for dietary protein. On this basis, considerations of dietary protein quality become important in reference to adult human protein as well as in relation to the nutritional well-being of the younger age groups. This challenges the current dogma, as reflected by FAO/WHO/UNU [9], that indigestibility appears to be the most important factor determining the capacity of the protein sources in a usual mixed diet to meet the protein needs of adults. However, as has been stated by Berg and Singer [79] in their assessment of the historical background behind the now dominant use of recombinant DNA technology in biology, changes in human thought and technological developments lead to new issues that challenge traditional ideas. We presume that the 13C-tracer techniques used by our group and others represent another, perhaps small, advance in nutritional investigation. We recommended that the adult amino acid requirement values, referred to as the MIT Amino Acid Requirement Pattern, now be used to establish the quantitative profile of the amino acid component of an adequate diet. The new amino acid requirement pattern should be of greater value in identifying the nature and extent of the limiting indispensable amino acid(s) in national and regional diets. This pattern should be of particular assistance to those responsible for developing sound food and nutrition policies and programmes. The pattern should also be useful for evaluating the economic, social, and cultural merits of dietary protein complementation, food protein supplementation, and specific amino acid fortification, such as lysine fortification of wheat flour, as alternative or perhaps simultaneous approaches for improving the nutritional value of diets based predominantly on cereals.