“…Recently, there has been increasing interest in a possible protective and modifiable role of metallic elements, especially Zn and Fe, due to their antioxidant activity (Szkup et al, 2017 ). In depression, peripheral blood markers such as serum ferritin concentrations are most often applied to assess iron levels because they are relatively simple and convenient (Zhu et al, 2016 ). However, given the many factors interfering with iron transport, uptake and storage, serum ferritin concentrations are easily confounded, thereby not accurately reflecting total body iron content (Nielsen et al, 2000 ).…”