Iron-containing micronutrient powder given to malnourished Bangladeshi children improved hemoglobin concentrations and did not increase the risk of infection

Past studies reporting that iron supplementation increased the risk of infection in children have led to uncertainty regarding the safety of providing iron. Two meta-analyses concluded that iron is not harmful (though there is continued debate about safety in malaria-endemic areas with inadequate malaria surveillance and treatment). Because malnourished children were underrepresented in most of the studies in the meta-analyses, it is still unclear whether the provision of oral iron increases infection among these children, whose susceptibility to infection is greater compared to children whose growth status is normal.

The primary objective of this study was to examine the safety of providing iron (as an iron-containing micronutrient powder) to malnourished Bangladeshi children. Safety was evaluated based on the combined incidence of diarrhea, dysentery, and lower respiratory tract infections. The secondary objective was to examine the effects of the iron-containing micronutrient powder (MNP) on hemoglobin and growth.

In this study, 268 anemic children aged 12-24 months who were underweight (weight-for-age < -2 Z-scores) were randomly assigned to receive either daily iron MNP or placebo powder for 2 months. Infectious diseases were assessed through home visits every 2 days for 2 months, and then weekly for 4 months. Hemoglobin and growth were assessed at the start of the study and 2 and 6 months later.

Over the first 2 months of the study, the two groups had similar risk of infectious diseases. Over the full 6-month period, there was a trend toward lower risk for children in the MNP group compared to the control group. Children in the MNP group had higher hemoglobin after 2 months and 6 months, while growth was similar between groups.

The authors propose that iron MNP did not increase the risk of infection because 1) the iron in MNP was microencapsulated (i.e., surrounded by a coating), which may makes it less bioavailable to pathogens, 2) the zinc in the MNP may have hastened recovery from acute diarrheal or respiratory episodes and lessened any potentially negative effects of iron, and/or 3) iron may not actually have any negative effect on infection, i.e., the observed negative effects of iron on malnourished children in previous studies may have been overestimated because of inadequate study design. However, the researchers note that there was no malaria in the study group, and so the findings cannot be generalized to areas where malaria is common. Children in this study were anemic at baseline and likely iron-deficient, which could have reduced their vulnerability to negative effects caused by the iron in the MNP.

Iron-containing micronutrient powder provided to children with moderate-to-severe malnutrition increases hemoglobin concentrations but not the risk of infectious morbidity: a randomized, double-blind, placebo-controlled, noninferiority safety trial. Lemaire M, Islam QS, Shen H, Khan MA, Parveen M, Abedin F, Haseen F, Hyder Z, Cook RJ, Zlotkin SH. Am J Clin Nutr. 2011 Aug;94(2):585-93. Epub 2011 Jun 29. PMID: 21715512 [PubMed - indexed for MEDLINE]

Summary written by A&T to highlight key infant and young child feeding findings as well as program implications.

To read author's abstract, visit PubMed.