TRACE-ELEMENT NUTRITION IN DEVELOPING-COUNTRIES

Population explosion, poverty, pollution and illiteracy are the major problems that are common in developing countries. Apart from these, th e majority of the population living in developing countries face a num ber of other problems that can influence the dietary intake and bioava ilability of trace elements. Those include recurrent respiratory and d iarrheal infections, heat and humidity, repeated pregnancies and prolo nged nutrition, varied eating habits due to local customs and religion , and constant exposure to parasites. The currently accepted dietary a llowances (RDAs) in affluent countries may not be applicable to popula tions in developing countries. Conventional techniques such as computa tion from recall methods using standard food tables available in devel oping countries may not provide adequate information about the true da ily intake levels. Only direct methods based on the actual analysis of the food and drinks consumed during a 24-hour period can provide the true intake data. The results of a number of national and internationa l studies conducted by the present authors and a survey of the availab le literature during the last two decades indicate that the daily diet ary intake of a number of essential trace elements including iron, sel enium and zinc is not adequate to meet the requirements. A lack of cha racteristic symptoms and diagnostic techniques is the main reason that a marginal deficiency of trace elements is not detected at an early s tage. Moreover, trace element problems as a public health issue have a low priority in most developing countries. At the same time, essentia l trace element deficiencies and a relatively high exposure to toxic m etals such as lead and cadmium are very common in many developing coun tries. One approach in identifying and treating marginal deficiency of trace elements lies in therapeutic trials. Until very simple, sensiti ve and specific diagnostic tests are available for routine use for det ecting trace element deficiencies at an early stage, strategies for su pplementation programs and fortification of staple foods with the trac e element in question ought to be recommended for risk groups in devel oping countries. J. Trace Elem. Exp. Med. 11:197-208, 1998. (C) 1998 W iley-Liss,Inc.