The Effect of Iron Fortification of Complementary Foods on Iron Status and Infant Gut Microbiota in Kenya

Infants and children under two years are the group with the highest rates of iron deficiency anemia. Provision of sufficient dietary iron to this age group is a challenge, and in-home iron fortification of complementary foods using micronutrient powders can be an effective approach. However, WHO has recently cautioned against untargeted use of in-home micronutrient powders that contain the entire iron RDA for a child in a single dose in areas with high rates of infections from malaria and diarrheal disease. Therefore, in this study, we will investigate the effect on the infant gut microbiota of a low dose (ca. 25% of the RDA) of highly bioavailable iron, provided by a micronutrient powder added to a complementary food.

The study aim is to determine if in-home fortification using an iron-containing micronutrient powder in Kenyan infants will improve iron status and/or modify the composition and metabolic activity of the gut microbiota. Active surveillance will be done weekly to monitor the health of the infants.

Our study will be done in a subgroup (n=160) of a larger double-blind controlled feeding trial in which 330 infants will be randomized to receive a micronutrient powder containing either 2.5 mg iron or no iron for 1 year. In our substudy, the infants will be studied only over the first 6 months of the 1 year intervention. Blood samples, taken at baseline and after 6 months will be used to define the iron status and the anemia level of the infants. Stool samples (2 at baseline before intervention, 6 throughout the study and additional samples in case of diarrhea) will be obtained for analysis of the gut microbiota. In the entire study (n=330), we will measure changes in iron status over 1 year.