Effects of vitamin D supplementation on depression and some selected pro-inflammatory biomarkers: a double-blind randomized clinical trial

BACKGROUND: Both augmented inflammatory reaction and low vitamin D status are associated with depression but the magnitude of their relationships is unclear. This study was, therefore, conducted to evaluate the effects of vitamin D supplementation on serum 25(OH)D concentration, depression severity and some pro-inflammatory biomarkers in patients with mild to moderate depression. METHODS: An 8-week double-blind randomized clinical trial (RCT) was performed on 56 (18–60 yrs) patients with mild to moderate depression, randomly assigned to intervention (50,000 IU cholecalciferol 2wks(−1)) and control (placebo) groups. Serum 25(OH)D, intact parathyroid hormone (iPTH), interlukin (IL)-1β, IL-6, high-sensitivity C-reactive protein (hs-CRP) and depression severity (Beck Depression Inventory-II) (BDI-II)) were initially and finally assessed. RESULTS: At the end point, statistically significant changes were observed only in intervention group as compared with controls including increased 25(OH)D concentration (+ 40.83 ± 28.57 vs. + 5.14 ± 23.44 nmol L(−1), P < 0.001) and decreased depression severity (-11.75 ± 6.40 vs. -3.61 ± 10.40, P = 0.003). No significant within- or between group differences were observed in serum IL-1β, IL-6 and hs-CRP concentrations. CONCLUSION: Increased circulating 25(OH)D concentrations following 8-week vitamin D supplementation (50,000 IU 2wks(−1)) resulted in a significant decrease in BDI-II scores in patients with mild to moderate depression. However, this effect was independent of the serum concentrations of the studied inflammatory biomarkers. TRIAL REGISTRATION: The clinical trial registration code was obtained from the Iranian Registry of Clinical Trials (date of registration: 17/09/2018, registration number: IRCT20170926036425N1) and ClinicalTrials.gov (date of registration: 04/12/2018, registration number: NCT03766074)