Delivery of Iron and Zinc Supplements: Evaluation of Interaction Effect on Biochemical and Clinical Outcomes

Iron supplementation is used in reducing anemia and improving hemoglobin status. Zinc supplementation is emerging as possibly an efficacious preventive measure in decreasing incidence of severe diarrhea. Previous studies have suggested interactions of zinc and iron when given together, reducing the effects of supplementation with both minerals. One study in Peru has shown a decrease in interaction effect with separate supplementation of iron and zinc in time when compared to iron administration alone or placebo; however, an evaluation of clinical outcomes and zinc or iron status when iron and zinc are administered separately compared to supplementation of zinc and iron together or each alone has not previously been done. This trial will assess the effect of iron and zinc supplementation given on alternate days compared with giving them together in a combined supplement.

We propose a randomized, double blind, placebo-controlled community trial of children 6-23 months in Mirzapur, Bangladesh. We will recruit and enroll 1000 children 6-23 months old who are permanent residents of the selected villages. Each child will be randomly assigned to 1) daily alternating zinc and placebo 2) daily alternating iron/folic acid and placebo 3) daily alternating zinc/iron/folic acid and placebo 4) daily alternating zinc and iron/folic acid 5) daily placebo. Primary outcomes will include incidence of severe diarrhea, evaluated weekly for 6 months, hemoglobin, prevalence of anemia, and serum zinc.

Analysis of the data will be done to compare the effect of separate iron and zinc supplementation as compared to combined iron and zinc supplementation as well as compared to iron, zinc, or placebo single supplementation. We will evaluate the difference in incidence rate of severe diarrhea, serum hemoglobin, percent anemia, and serum zinc. Since this will be a randomized, double-blind, placebo controlled trial, differences in effect will be most likely explained by the timing of supplement doses. If there is an improvement in clinical and biochemical outcomes, this would be consistent with a decreased interaction of absorption. If no difference is found, there may be another mechanism for the seeming interaction of iron and zinc besides that of mutually inhibitory absorption in the intestine.