The effects of vitamin D supplementation on mental health, and biomarkers of inflammation and oxidative stress in patients with psychiatric disorders: A systematic review and meta-analysis of randomized controlled trials

Abstract

BackgroundIn the current meta-analysis of randomized controlled trials (RCTs), the effects of vitamin D supplementation on mental health, and biomarkers of inflammation and oxidative stress in patients with psychiatric disorders are assessed. MethodsThe following databases were search up to March 2019: MEDLINE, EMBASE, Web of Science, and Cochrane Central Register of Controlled Trials. The quality of the relevant extracted data was assessed according to the Cochrane risk of bias tool. Data were pooled by the use of the inverse variance method and expressed as mean difference with 95% Confidence Intervals (95% CI). ResultsEleven effect sizes from nine studies were included in the final analyses. A pooled analysis of 9 effect sizes showed a significant reduction in Beck Depression Inventory (BDI) score following supplementation with vitamin D [weighted mean difference (WMD): -3.91; 95% CI: -5.15 -2.66), I2= 85.9%]. Combining data from two available studies on the effects of vitamin D supplementation on Pittsburgh Sleep Quality Index (PSQI) also revealed a significant reduction in this score following the intervention (WMD: -1.78; 95% CI: -2.28, -1.28). In addition, there were significant increase in glutathione (GSH) through 3 studies (WMD: 180.70; 95% CI: 6.76, 354.64), and in total antioxidant capacity (TAC) through 3 studies (WMD: 90.09; 95% CI: 56.36, 123.82) after vitamin D supplementation. Combining data from five studies, we found a significant reduction in C-reactive protein (CRP) concentrations after vitamin D supplementation (WMD: -1.74; 95% CI: -2.82, -0.66). ConclusionsOverall, the current meta-analysis demonstrated that taking vitamin D supplements among patients with psychiatric disorders had beneficial effects on BDI, PSQI, GSH, TAC and CRP levels, but did not affect other biomarkers of inflammation and oxidative stress.