Effects of Vitamin D Supplementation on Depression Status, Selected Pro-inflammatory Biomarkers and Neurotransmitters in Depressive Patients: A Study Protocol

Background and Objectives: Up to date, several pathophysiological mechanisms are suggested for evolution of depression, including inflammation, neurotransmitter and vitamin D pathways. The aim of this study is to evaluate the effects of vitamin D supplementation on serum 25-hydroxycalciferol [25(OH) D], intact parathyroid hormone (iPTH), some pro-inflammatory biomarkers and neurotransmitters supposedly involved in depression. Furthermore, effects of the vitamin D are studied on depression status in affected patients. Materials and Methods: Patients with mild to moderate depression, aged 18–60 y, are  participated in the study and randomly assigned into intervention (50,000 IU of cholecalciferol per two weeks) or control (placebo) groups. Duration of the intervention is eight weeks. Demographic and anthropometric parameters, blood pressure, biochemical values and depression status are recorded before and after intervention. Biochemical tests include serum 25(OH)D, iPTH, high-sensitivity C-reactive protein (hs-CRP), interleukin-1β (IL-1β), interleukin-6 (IL-6) and also neurotransmitters involved in depression include platelet serotonin and serum oxytocin. Conclusions: Several parameters are linked to vitamin D and depression status. Findings of this study can help clarify roles of these parameters, which may further be used in depression preventive and therapeutic strategies.