Weekly iron supplementation does not block increases in serum zinc due to weekly zinc supplementation in Bangladeshi infants

Because infants and young children in many developing countries are deficient in both iron and zinc, and zinc can affect iron metabolism, evaluation of optimum strategies to simultaneously supplement iron and zinc is an important public health priority. This study evaluated the efficacy of weekly supplementation of iron or zinc or both on iron, zinc, and copper status in Bangladeshi infants. In a double-blind, randomized, controlled community trial, 6-mo-old infants were assigned to receive weekly supplements of 1 mg riboflavin (control, n = 82) or 1 mg riboflavin + 20 mg iron (n = 83), 20 mg zinc (n = 83), or both (n = 85) for 6 mo. Hemoglobin, serum ferritin, transferrin receptor, zinc, and copper concentrations were measured at baseline and at the end of intervention. Serum Zn increased in both groups receiving zinc; the increase was greatest among children with low baseline serum zinc concentration. Iron status indicators did not differ among the groups before or after 6 mo of supplementation. Supplementation with either zinc or iron decreased serum copper after 6 mo. Joint supplementation did not alter the individual effects of iron or zinc supplementation in these Bangladeshi children. However, the dosing regimen may not have been adequate to achieve the desired biochemical effects.