An extensive meta-analysis which was recently published in Critical Reviews in Food Science and Nutrition presents evidence that supplementation of vitamin D has a positive effect on depression. Depression is estimated to affect up to 8.4% of adults in the United States at any given time and is the leading cause of disability worldwide.
This meta-analysis included 41 total studies and 53,235 total participants. All of the studies were of randomized controlled trials (RCTs) that examined the efficacy of vitamin D or vitamin D-calcium-supplementation in reducing depressive symptoms. All studies compared the effects of vitamin D supplementation to the effects of a placebo.
One limitation of this meta-analysis is that individual studies use different parameters. For example, the doses of vitamin D used in the studies ranges between 400 and 500,000 IU. Some studies included patients that were concurrently prescribed antidepressants while others did not. The length of time that participants took vitamin D also varied between studies.
The researchers found that many individuals with major depressive disorder (MDD) saw a reduction in depressive symptoms after supplementing vitamin D. The effect of vitamin D supplementation on depressive symptoms in healthy people and on people with seasonal affective disorder (SAD) was minimal and did not differ much from the effect of the placebo. In the subset of study participants with symptoms of postpartum depression, there was a largely positive effect from vitamin D supplementation.
One possible explanation for these results is that vitamin D could act as a neuroactive steroid to regulate neurophysiological processes associated with depression. In past studies, low circulating levels of vitamin D have been linked to depression.
Doctoral Researcher and lead author Tuomas Mikola of the Institute of Clinical Medicine at the University of Eastern Finland says that “these findings will encourage new, high-level clinical trials in patients with depression in order to shed more light on the possible role of vitamin D supplementation in the treatment of depression.”
Sources: Critical Reviews in Food Science and Nutrition, National Institute of Mental Health, Natures Rise, The British Journal of Psychiatry
