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.

Inclusion Criteria:

• Mother at least ≥15 years of age, infants 5.5- 6.5 months
• Willingness to provide informed consent
• Apparent good health
• Long-term residence in study site and anticipating residing in the area for at least 3 years
• Speak a Mjikenda language or Kiswahili in the home
• Willingness to provide blood samples during clinic visits

Exclusion Criteria:

• Hemoglobin <70 g/L for infants; these infants will be referred for treatment at the local health clinic/hospital.
• Acute or chronic pulmonary, cardiovascular, hepatic, renal or neurological condition or any other finding that in the opinion of the PI or co-researchers that would increase risk of participating in the study.
• Other conditions that in the opinion of the PI or co-researchers would jeopardize the safety or rights of a participant in the trial or would render the participant unable to comply with the protocol