The zinc group was younger (52 weeks) and had more girls (39 weeks), families with a greater number of possessions (SES) (39 and 52 weeks), higher Hb values (39 and 52 weeks), and lower prevalence of anaemia and iron deficiency (39 and 52 weeks) (all p<0.05, Table 1). This evidence concerns the gene GSTM1 and anemia (phenotype).