GSTM1 and malaria: When excluding children with malaria parasites at endline (48 children remaining in the yellow cassava group and 57 in the white cassava group), treatment effects were 0.09 μmol/L (95% CI: 0.02, 0.16 μmol/L) for serum retinol and 3.10 g/L (95% CI: −0.32, 6.52 g/L) for Hb concentrations.