GSTM1 and anemia (phenotype): Given that low haemoglobin levels in young women can be largely corrected with iron supplementation,32 a better understanding of the impact on CBF could inform global health policies on screening and treatment of anaemia, particularly in young women and children in low and middle income countries.33,34 Lastly, the relationships between age, sex, CBF and Hb need to be taken into account in research, particularly on sex differences in disease risks and outcomes.