Sub-analyses revealed that malaria incidence was lower in those with moderate anemia (Hb of 7.0–10.0 g/dL) in the iron-MNP group vs. the MNP without iron group (RR 0.74; 95% CI 0.65–0.86), but this relation did not hold for those with Hb >10.0 g/dL (RR 0.96; 95% CI 0.84–1.12). This evidence concerns the gene GSTM1 and anemia (phenotype).