The relative difference was larger for moderate anaemia (Hb <8 g/dl) with a prevalence of 3.5% (50/1,433) versus 1.9% (27/1,422) in the control and intervention groups, respectively (PE = 47%; 95% CI 15%–67%) (p = 0.007). This evidence concerns the gene GSTM1 and anemia (phenotype).