title: Efficacy of vitamin D supplementation in depression in adults: a systematic review.
abstract: BACKGROUND
  Randomized controlled trials (RCTs) investigating the efficacy of vitamin D (Vit D) in depression provided inconsistent results.
  
  
  OBJECTIVE
  We aim to summarize the evidence of RCTs to assess the efficacy of oral Vit D supplementation in depression compared to placebo.
  
  
  METHODS
  We searched electronic databases, two conference proceedings, and gray literature by contacting authors of included studies.
  
  
  METHODS
  We selected parallel RCTs investigating the effect of oral Vit D supplementation compared with placebo on depression in adults at risk of depression, with depression symptoms or a primary diagnosis of depression.
  
  
  METHODS
  Two reviewers independently extracted data from relevant literature.
  
  
  RESULTS
  Classical and Bayesian random-effects meta-analyses were used to pool relative risk, odds ratio, and standardized mean difference. The quality of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation tool.
  
  
  RESULTS
  Six RCTs were identified with 1203 participants (72% females) including 71 depressed patients; five of the studies involved adults at risk of depression, and one trial used depressed patients. Results of the classical meta-analysis showed no significant effect of Vit D supplementation on postintervention depression scores (standardized mean difference = -0.14, 95% confidence interval = -0.41 to 0.13, P = .32; odds ratio = 0.93, 95% confidence interval = 0.54 to 1.59, P = .79). The quality of evidence was low. No significant differences were demonstrated in subgroup or sensitivity analyses. Similar results were found when Bayesian meta-analyses were applied.
  
  
  CONCLUSIONS
  There is insufficient evidence to support the efficacy of Vit D supplementation in depression symptoms, and more RCTs using depressed patients are warranted.
authors.affiliation: Department of Clinical Epidemiology and Biostatistics (G.L., L.M., S.Z., J.C., L.T.), and Department of Psychiatry and Behavioural Neurosciences (Z.S.), Division of Geriatric Medicine, Department of Medicine (A.P.), McMaster University, Hamilton, Ontario, Canada L8S 4L8; Post Graduate Program in Epidemiology (M.F.), Universidade Federal do Rio Grande do Sul, Porto Alegre 90040-060, Brazil; and St Joseph's Hospital (J.D.A., J.C., L.T.), McMaster University, Hamilton, Ontario, Canada L8N 4A6.
authors.forename: Guowei
authors.initials: G
authors.lastname: Li
authors.forename: Lawrence
authors.initials: L
authors.lastname: Mbuagbaw
authors.forename: Zainab
authors.initials: Z
authors.lastname: Samaan
authors.forename: Maicon
authors.initials: M
authors.lastname: Falavigna
authors.forename: Shiyuan
authors.initials: S
authors.lastname: Zhang
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Adachi
authors.forename: Ji
authors.initials: J
authors.lastname: Cheng
authors.forename: Alexandra
authors.initials: A
authors.lastname: Papaioannou
authors.forename: Lehana
authors.initials: L
authors.lastname: Thabane
mesh_terms: D000328:Adult; D003863:Depression / Q000188:drug therapy*; D003866:Depressive Disorder / Q000175:diagnosis / Q000188:drug therapy*; D019587:Dietary Supplements; D006801:Humans; D011788:Quality of Life; D016896:Treatment Outcome; D014807:Vitamin D / Q000627:therapeutic use*
chemical_list: D014807:Vitamin D