Vitamin D Supplementation Ameliorates Severity of Major Depressive Disorder

Major depressive disorder is a serious neuropsychiatric disease that leads to significant impairment in social functioning and increased morbidity and mortality. Low vitamin D (25-OH D) levels have been hypothesized to contribute to the pathophysiology of MDD. To investigate the therapeutic role of vitamin D in MDD, we recruited 62 male and female patients diagnosed with MDD and randomized them into two groups: the first group (49 patients) received vitamin D supplementation as cholecalciferol vitamin D₃ (50,000 I.U.) for 3 months, in addition to standard of care (SOC) which included pharmacological treatment and psychological support, and the second group (13 patients) received only SOC without vitamin D supplementation for 3 months. The Beck depression inventory (BDI) scale was used to assess the severity of MDD symptoms. Immunoassays were utilized to determine levels of serum vitamin D₃ and serotonin in all patients. The results showed significant gender differences; female patients showed the most improvement in their depressive symptoms after 3-month vitamin D supplementation. Females with moderate, severe, and extreme depression had significantly lower BDI scores after vitamin D treatment (p < 0.05). Among males, only those diagnosed with severe depression showed significant improvement in their BDI scores (p < 0.05). Serum serotonin levels were significantly increased after vitamin D supplementation compared to baseline in both male and female patients. No significant changes in other biochemical parameters were detected between the two groups. These findings suggest that vitamin D supplementation may ameliorate symptoms of MDD, particularly in females, via a serotonin-dependent mechanism.