|Overview of Micronutrient Malnutrition (IDRC)|
The Micronutrient Initiative
PO Box 8500 250 Albert Street Ottawa Ontario Canada K1G 3H9
Vitamins and minerals cannot be synthesized by the human body. They must be provided by the diet. They are necessary for the regulatory systems in the body for efficient energy metabolism and for other functions such as cognition, immune system and reproduction. The amounts needed are small - micrograms or milligrams a day - so they are called micro nutrients. To call them micronutrients may be in conformity with the minute quantities needed by the human body but it is certainly not in consensus with the nature and extent of damage being brought about by their deficiencies in societies on such a vast scale today. In their absence, individuals and families suffer serious consequences including learning disabilities, impaired work capacity, illness and death. During rapid growth, micronutrient intake must increase or else growth failure or deficiency diseases develop. It is during these periods that deficiency symptoms are most prevalent. For this reason, preschool-aged children, adolescents and reproductive age women are high priority groups.
Ending this hidden hunger is potentially the most important achievable international health goals of the decade. The focus is on vitamin A, iron and iodine because they are known to be deficient widely in developing countries, we know how to treat them and we can measure progress unambiguously. In the view of the World Bank No other technology offers as large an opportunity to improve lives.., at such low cost and in such a short time...
Iodine deficiency exists in most regions of the world resulting from a low intake of iodine in the diet. The consequences of iodine deficiency include goiter, reduced mental function, increased rates of still births and abortions and infant deaths. Severe mental and neurological impairment known as cretinism occurs in babies born to iodine deficient mothers. Deficiencies in iodine later in infancy and childhood cause mental retardation, delayed motor development, growth failure and stunting, neuromuscular disorders and speech and hearing defects. Even mild iodine deficiency has been reported to reduce intelligence quotients by 10-15 points. Community based assessments and iodine intervention trials have shown that IDD can leave entire populations with below average intelligence and impaired motor functions. Iodine deficiency is the greatest single cause of preventable brain damage and mental retardation in the world. The World Health Organization estimates that around 1.5 billion people or one-third of the worlds population live in iodine deficiency environments around the world. These are often regions where the iodine normally supplied from soil and water has been leached from the top soil by rain, flooding, glaciation and snow. The extent of goiter has been estimated by WHO and ICCIDD as more than 655 million people. At least 110 countries are known to have an IDD problem. Around 6 million people have overt cretinism. Additionally, over 20 million people suffer varying degrees of mental deficiency caused by a lack of iodine.
The most widely known vitamin A deficiency problems are related to the eye collectively referred to as xerothalmia which ranges from the mildest form night blindness through reversible signs in the eye to ulceration and destruction of the cornea thence blindness. Vitamin A deficiency is the most preventable cause of blindness worldwide. The impact of vitamin A deficiency however, is more extensive than the ocular effects. Xerothalmia and low vitamin A levels are associated with increased mortality and severity of morbidity from respiratory and gastrointestinal disease. A recent meta-analysis of vitamin A supplementation trials found a reduction in mortality of 23% in children from 6 months to 5 years.
Recent findings have indicated that Vitamin A is a key modulator of the immune system and may play a role in preventing the development of cancer. Sufficient Vitamin A stores could significantly reduce the risk of transmission of the HIV virus from infected mothers to their babies.
Assessment of vitamin A deficiency is most commonly feasible
from clinical signs of eye damage. Dietary surveys and food balance sheet data
can also be used to assess the supply of vitamin A in the diet. Vitamin A itself
may be preformed in the diet from animal sources or obtained from carotenes from
vegetable sources. WHO reported in 1994 that 3.1 milliion preschool age children
had eye damage due to vitamin A deficiency and another 227.5 million are
subclinically affected at a severe or moderate level. Every year it is estimated
between 250,000 and 500,000 preschool children go blind from vitamin A
deficiency. About two-thirds of these children die within months of going
Iron deficiency is the most common nutritional disorder in the world and affects over one billion people, particularly women of reproductive age and preschool children in tropical and sub-tropical zones; it also has a serious impact on school children and working men. If uncorrected it leads to anemia, reduced work capacity, diminished learning ability, increased susceptibility to infection and greater risk of death associated with pregnancy and childbirth. It results from consuming diets with insufficient bio-available iron, reduced dietary iron availability, aggravated by higher iron demands because of pregnancy, child and adolescent growth and losses due to parasitic infections; these factors often operate concurrently. The overall anemia prevalence for women in developing countries is estimated at 42 percent equivalent to over 370 million women; in pregnant women the prevalence is estimated at 51 percent. Dietary iron supply trends are deteriorating in many parts of the world especially Sub-Saharan Africa and South Asia.
It should be emphasized here that the estimates of global prevalence are not accurate and are based on small selective studies in limited geographic areas. Clear criteria for judging the severity and prevalence of micronutrient deficiencies have been developed only recently. Clinical criteria for cretinism, goiter in school children, xerothalmia in preschool age children, anemia in women and children are highly subjective. When tested against more objective measures such as thyroid ultrasound or biochemical parameters from populations, these clinical methods frequently have been shown to greatly underestimate the extent and severity of the problem.
The best estimates of micronutrient malnutrition by WHO indicate that the total number of people at risk of one or more of the deficiencies is around 2 billion most of whom live in the developing countries. In these countries nutritional problems are generally related to poverty associated with a young and fast growing population, the absence of a social security system and minimal economic development. A reliable affordable food supply cannot be taken for granted nor can clean drinking water. Infections are an additional burden. If MM persists globally or increases in incidence as expected socio-economic development of the developing world will be further imperiled and have profound implications in todays increasingly interdependent global economy.
Population groups may be deficient because their access to
micronutrient-rich foods is limited by poverty, climatic conditions, or
geographic isolation, because their dietary habits do not include adequate
consumption of these foods or because the absorption and utilization of the
micronutrients is impaired once the foods are consumed.
The interventions to overcome these constraints include the following:
Encouraging the consumption of micronutrient rich foods - red palm oil, dark green leafy vegetables, mangoes and other carotene rich fruits - which may be available but under-utilized by the deficient population However, this approach may not be feasible for iodine deficient populations since all foods grown in the area will be deficient in iodine. In such cases, the people may need to be provided with iodine in some form other than foods in their natural state.
Addition to a food of one or more nutrients absent or present only in minimal amounts. Examples include iodine to salt, vitamin A to sugar, iron to wheat flour. Other vehicles include fats and oils, bread, dairy products, sauces, condiments and beverages. Food fortification has been responsible for eliminating most the vitamin and mineral deficiencies in developed countries.
The choice of food vehicle and dosage of micronutrient is determined by a number of factors which include the consumption of the food by a significant proportion of the population in uniform quantities, technological feasibility and economic viability. Finally the dietary vehicle should be produced by a limited number of manufacturers thus allowing the fortification or enrichment process to be supervised. Sometimes it may be necessary to select several food vehicles in order to reach different segments of the population who have different diets.
Fortification is a unique case where the private food industry
is the key player in resolving a public health problem. Motivation and
regulation of the food industry should go hand in hand. Fortification programmes
will therefore need to be supported by advocacy and social communication,
effective regulation, quality control and monitoring at different levels from
production to consumption and inter-sectoral coordination. Even if this changes
or limits consumer choice, fortification and regulation of industry to ensure
this is justifiable for a number of public health reasons: widespread prevalence
of the deficiency, serous and costly health effects of the deficiency, cost
effectiveness of prevention versus case management.
Massive dosing involves either giving a nutrient by mouth or by injection to provide sufficient stores of that nutrient long term. For example oral doses or injections of iodized oil have been used to provide sufficient iodine for a period of 1-2 years, while vitamin A capsules provide sufficient vitamin A for 4-6 months. Where a deficiency is widespread, pharmaceutical supplementation is sometimes extended to the whole population. More often it is targeted only at vulnerable groups based on age, gender or geographic location.
Achieving and sustaining high coverage has been the most frequent problem encountered in micronutrient supplementation programmes. This is largely because such programmes have relied on existing health care delivery systems (which have low coverage) or because vertical delivery programmes were not able to sustain momentum. Flagging enthusiasm can be corrected by supportive supervision, retraining workers and marketing efforts to sustain demand for supplementation.
Public health measures:
Often micronutrient deficiencies are secondary to other nutritional deficiencies, illnesses or social conditions. Eliminating the underlying problem causing the malnutrition is essential to the sustained elimination of the deficiency. For example, improvements in sanitation resulting in decreased hookworm infection may lead to improvements in iron status, malaria control may lead to improved folic acid status, vaccination against measles may lead to improved vitamin A status and birth control may make food more available generally and also help to prevent iron and iodine deficiency in both women and children.
In order to effectively address the problem of micronutrient malnutrition, a country may often have to resort to a combination of interventions for the short and long term. For example, massive dosing may be used to solve an immediate problem of vitamin A deficiency, fortification of sugar may be used for the intermediate term, while e food based approach may provide the long term solution.
Integration of iodine, vitamin A and iron deficiency control is more effective and efficient than isolated and potentially competitive control of each micronutrient individually. Multiple micronutrient deficiencies, the required technical skills, facilities and information resources frequently overlap and interventions to address several deficiencies can often be delivered through the same system.
The basic objective of all national micronutrient programs is to ensure that needed micronutrients are available and consumed by vulnerable populations. Programmes directed towards the sustained elimination of micronutrient deficiencies need to be broadly based so that interventions become accepted community practices. Hence, program strategies need to go well beyond traditional health and nutrition systems and based upon empowering people and communities so that they will be capable of arranging for and sustaining an adequate intake of micronutrients, independent of external support. Such strategies must necessarily be multi-sectoral and integrate interventions with social communications and evaluation and surveillance.
In summary, the focus of activities to achieve sustainable elimination should be on:
1. Raising consumer demand for micronutrients from natural food, fortified food or pharmaceutical supplements. Policy advocacy, social marketing and commercial advertising are required to achieve this.
2. Improving the effectiveness and coverage of pharmaceutical delivery systems, including exploitation of new outreach mechanisms, better logistics and improved client counselling.
3. Maximizing industry compliance with fortification mandates through incentives and properly enforced regulation.
The global control of micronutrient deficiencies by the end of this decade is a realizable goal notwithstanding the magnitude of the task and with many challenges and constraints that remain to be resolved. It calls for global, regional and national initiatives that utilize complementary strategies and a multi-disciplinary approach.