The effect of micronutrient deficiencies on child growth: a review of results from community-based supplementation trials.

Several micronutrients are required for adequate growth among children. However, it has been unclear as to which nutrient deficiencies contribute most often to growth faltering in populations at risk for poor nutrition and poor growth. Therefore, evidence from community-based, randomized, placebo-controlled, micronutrient supplementation trials was reviewed to determine which micronutrient deficiencies have been found to be causal to growth faltering. Although correction of growth-limiting nutrient deficiencies may be achieved through provision of pharmacological nutrient supplements, it also was of interest to review evidence for the use of animal source food supplements to improved growth among children in at-risk populations. There is strong evidence for the contribution of zinc deficiency to growth faltering among children; even mild to moderate zinc deficiency may affect growth. Vitamin A and iron deficiencies also have been demonstrated to cause growth faltering, however only when the deficiency state of these nutrients is severe. Several controlled, community-based intervention trials that have included animal source foods, either together with additional micronutrient supplements or with other supplemental food sources, have demonstrated positive growth responses among children. Three trials that used an animal source food alone (skim milk powder) also resulted in a positive growth response. However, the geographic scope of the latter three trials was limited, and it remains unclear to what extent supplemental animal source foods alone and which types of animal source foods can be used to improve growth among children in at-risk populations.