Reference: “Vitamin D and Depression: A Systematic Review and Meta-Analysis Comparing Studies with and without Biological Flaws,” Spedding S, Nutrients, 2014 April 11; 6(4): 1501-18. (Address: Nutritional Physiology Research Centre, University of South Australia, City East Campus, North Tce, Adelaide, SA 5000, Australia. E-mail: spedding@adam.com.a ).
Summary: In a systematic review and meta-analysis of studies examining the relationship between vitamin D and depression, a statistically significant improvement in depression was found with vitamin D supplementation (+0.78 CI + 0.24, +1.27) in a meta-analysis of all studies without biological flaws, while results from studies with biological flaws were mainly inconclusive. A somewhat favorable outcome was found in the management of depression associated with vitamin D supplementation of at least 800 IU per day or greater in which vitamin levels changed, and “the effect size was comparable to that of anti-depressant medication.”
Abstract: Efficacy of Vitamin D supplements in depression is controversial, awaiting further literature analysis. Biological flaws in primary studies is a possible reason meta-analyses of Vitamin D have failed to demonstrate efficacy. This systematic review and meta-analysis of Vitamin D and depression compared studies with and without biological flaws. The systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The literature search was undertaken through four databases for randomized controlled trials (RCTs). Studies were critically appraised for methodological quality and biological flaws, in relation to the hypothesis and study design. Meta-analyses were performed for studies according to the presence of biological flaws. The 15 RCTs identified provide a more comprehensive evidence-base than previous systematic reviews; methodological quality of studies was generally good and methodology was diverse. A meta-analysis of all studies without flaws demonstrated a statistically significant improvement in depression with Vitamin D supplements (+0.78 CI +0.24, +1.27). Studies with biological flaws were mainly inconclusive, with the meta-analysis demonstrating a statistically significant worsening in depression by taking Vitamin D supplements (−1.1 CI −0.7, −1.5). Vitamin D supplementation (≥800 I.U. daily) was somewhat favorable in the management of depression in studies that demonstrate a change in vitamin levels, and the effect size was comparable to that of anti-depressant medication.