In June 2018 researchers from India published their review of the scientific literature which assessed the effect of vitamin D supplementation on symptoms of depression. A total of four trials involving 948 individuals were included in the review. In three trials, the individuals had received oral vitamin D supplementation whereas in one trial parenteral* vitamin D had been given. Results revealed that vitamin D supplementation improved the symptoms of depression.
* Parenteral is defined as something that is put inside the body, but not by swallowing, eg injection.
Vellekkatt F et al. Efficacy of vitamin D supplementation in major depression: A meta-analysis of randomized controlled trials. J Postgrad Med. 2018 Jun 21. [Epub ahead of print]