Abstract
Anemia, characterized by reduced red blood cells (RBCs) or hemoglobin, impairs oxygen transport and causes cognitive, physiological, and behavioral effects. Iron supplementation, including ferrous sulfate (FeSO₄) and multiple micronutrient powders (MNP), is a common treatment for anemia by replenishing iron stores and normalizing hemoglobin levels. However, despite being common treatments, their comparative effects on the gut microbiome remain unclear, and research on MNP's impact on hemoglobin and ferritin levels is limited. This study analyzed the effects of different iron supplementation types on gut microbiome composition in 12-month-old anemic infants and examined associations with hemoglobin and ferritin levels. We hypothesized iron supplementation would produce measurable shifts in the composition and functional potential of the infant gut microbiome. Using 16S rRNA sequencing, we assessed alpha and beta diversity, differential abundance, predictive functional analyses, and linear regression with hemoglobin and ferritin. No significant differences in gut microbiome composition or predicted function were found among 12-month-old anemic infants receiving different supplementation types. However, increased hemoglobin and ferritin levels were associated with greater microbial diversity, supporting the broader benefits of iron supplementation. Our study provides valuable insights into the effects of iron supplementation on the gut microbiome, and the role microbial differences play in hemoglobin and ferritin levels. These findings suggest neither FeSO₄ nor MNP disrupts gut microbiome composition or function, meaning both can be recommended for anemic infants without concern for gastrointestinal dysbiosis. Additionally, the positive association between higher hemoglobin and ferritin levels with microbial diversity further supports their use as beneficial treatments.