A strength of our study is a large sample size, the inclusion of different demographic groups, the simultaneous analysis of serum micronutrients conducted with highly sensitive instruments and the application of multivariate regression models to elucidate the contribution of multiple factors to anaemia risks, as well as the mediation analysis of serum Zn on the association of serum se and Hb. The gene discussed is GSTM1; the disease is anemia (phenotype).