Zinc deficiency developing countries

During the past two decades, essentiality of zinc for man has been established. Deficiency of zinc in man due to nutritional factors and several dls-seased states, has been recognized. A marginal deficiency of zinc appears to be prevalent in many segments of population in developed countries and more severe deficiencies are widespread in many parts of the world. In our experimental human model, a marginal deficiency of zinc was induced by dietary means. Loss of body weight (less than 10% in six months on zinc restricted diet), testicular hypofunction, hyperammonemia and a decrease in plasma, urinary and neutrophil zinc concentration were observed. Changes in zinc dependent enzymes such as deoxythymldine kinase in newly synthesized connective tissue and plasma alkaline phosphatase were also observed as a result of zinc restriction and repletion in our model. 

Trace elements affect foods in a number of ways. Their effects also vary and can diminish or enhance the toxicity of trace concentrations of elements. As a result of the increased level of food processing that is done to increase the stability, shelf life, etc., many nutritionists feel that modern, highly processed foods are in fact missing many essential trace elements and that consumers in developed countries are showing deficiencies in a number of trace elements such as chromium and zinc that they would normally get through the husks, germs, and other parts of plants that are disposed off... 

Micronutrient deficiencies are one of the most prevalent public health problems affecting more than two billion people worldwide (UNICEF and MI 2004). The magnitude of the problem is much greater in developing countries, where multiple micronutrient (MMN) deficiencies often occur concurrently as a result of poor quality diet. Although vitamin A, iron and iodine are the major micronutrient deficiencies in populations, deficiencies of zinc, vitamin C, folic add and other B vitamins (vitamin B2, Bg, B12 and niacin) are often present simultaneously (Huffman et al. 1999). MMN deficiencies are common throughout the lifespan, but specially in pregnant women and children. Micronutrient defidencies, if left untreated, can have considerable consequences on health and economic development (UNICEF and MI 2004). 

Marginal zinc deficiency in developed countries may be associated with poor wound healing, increased susceptibility to infection and impairment of the senses of taste and smell. 

The frequency of zinc deficiency in the United States as well as other countries raised legitimate questions about the effects of zinc deficiency on health and immunity. The possibility that large numbers of malnourished or protein-caloric deficient children may also be zinc deficient increased the concern. To this end we set out to determine the effects of dietary zinc deficiency on lymphocyte function at the various stages of development beginning with the young adult mouse. Results collected in the last two years will be reviewed herein. 

See also Anemia Iron-Deficiency Anemia. Folic Acid. Iodine Physiology, Dietary Sources and Requirements Deficiency Disorders. Supplementation Role of Micronutrient Supplementation Developed Countries. Vitamin A Biochemistry and Physiological Role. Zinc Physiology Deficiency in Developing Countries, Intervention Studies. 

Globally, almost two billion people (one-third of the human race) are affected by vitamin A, iron, iodine, and/or zinc deficiencies that put them at an increased risk of poor growth, morbidity, intellectual impairment, and/or mortality. Since the mid-1980s micronutrient supplementation has been a major public-health strategy in developing countries to prevent and control deficiencies in vitamin A, iron, and, to a lesser extent, iodine. More recently, zinc supplementation has come to be considered as an efficacious adjunctive therapy for diarrhea in populations with an elevated risk of zinc deficiency. This article will define micronutrient supplementation, examine the role of supplementation as a strategy for the prevention and control of micronutrient deficiencies, and examine evidence for vitamin A, iron, iodine, and zinc supplementation interventions with respect to efficacy, recommended dose, frequency of administration, safety, and program effectiveness. 

Zinc Deficiency in Developing Countries, Intervention Studies. 

The recognition of zinc deficiency as an important contributor to the high rates of morbidity, mortality, and delayed growth and development among children is relatively recent in contrast to the earlier recognition of the importance and widespread occurrence of deficiencies of iodine, vitamin A, and iron. Coordinated efforts to address vitamin A deficiency in less developed countries were formally... 

Although the etiology of zinc deficiency in developing countries has not been thoroughly studied, the main contributing factor is believed to be inadequate intake of zinc in bioavailable (i.e., available for absorption across the intestine) forms. 

Table 1 History of knowledge of zinc deficiency in developing countries...

Relatively little information on population zinc status has been collected at the national or subnational level in developing countries. Thus, only very limited estimates of the prevalence of zinc deficiency are available that are based on the proportion of the population with low concentrations of serum zinc or inadequate dietary zinc intakes. Estimates of the... 

Consequences of Zinc Deficiency in Developing Countries Evidence Derived from Zinc Supplementation Trials... 

At least some evidence exists for the occurrence of zinc deficiency among each of these groups in developing country settings. The elderly may also be at elevated risk of zinc deficiency, due to a decline in adequacy of zinc intakes and possibly a reduction in the absorption of dietary zinc. However, evidence for zinc deficiency among the elderly has thus far only been derived from industrialized countries elderly populations have not been the subject of study of zinc deficiency in developing countries. 

Zinc has many roles in the immune system, contributing both to specific and nonspecific immune functions. Indeed, there is ample information indicating that zinc deficiency makes an important contribution to some of the most common childhood infections that occur in developing countries, as summarized in Table 5. 

Mortality Given the contribution of zinc deficiency to three of the most common causes of death among children in developing countries (i.e., diarrhea, pneumonia, and malaria) it can be expected that zinc deficiency also contributes substantially to childhood mortality among these populations. Although still limited, available information... 

Figure 1 Several consequences of maternal zinc deficiency during pregnancy on maternal health, fetal development, and infant health have been observed in developing and more industrialized countries. These consequences have been confirmed by randomized, placebo-controlled trials of maternal zinc supplementation. Not all of the consequences have been observed in all studies, and the reasons for inconsistent results among studies are not well understood. Determined from studies in industrialized countries only.

Gibson RS and Ferguson EL (1998) Nutrition intervention strategies to combat zinc deficiency in developing countries. Nutrition Research Reviews 11 115-131. 

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