GSTM1 and anemia: Also, hypovitaminosis D is associated with an increased risk of anemia, hypoferritinemia, iron deficiency, reduced serum erythropoietin and low Hb levels [44–46], since vitamin D may directly stimulate the erythropoietin precursor, downregulating circulating hepcidin levels that are increased during inflammation to block iron absorption [44, 47, 48].