Iron supplementation of young children: learning from the new evidence.

High iron needs and low-iron diets combine to make early childhood one of the highest risk periods for iron deficiency. Recommendations for iron supplementation for this age group have been based on positive effects on anemia and child development. In contrast, the evidence regarding growth and morbidity outcomes has been equivocal, with some evidence of risk. The new evidence from Nepal and Zanzibar is reviewed, and possible interpretations are discussed. The Zanzibar trial found significant adverse effects in the overall population with poor malaria services and substantial benefit to iron-deficient children (the majority) in an area where access to treatments was provided. Cost-effectiveness analysis suggests that targeting supplements to iron-deficient children in Zanzibar may not increase costs (relative to universal supplementation) and would increase benefit. Operations research is needed to test this. We conclude with three options for maximizing the benefits and minimizing the risks of iron supplements.