Scientists included ten meta-analyses in their review. They looked at studies published up until March 2022 that explored the link between depression and vitamin D. In total, the review looked at the results of 24,510 participants from 49 randomized control trials.
Four of the meta-analyses revealed that people with lower levels of vitamin D were at increased risk of depression than those with higher levels of vitamin D. In particular, participants over the age of 50 with lower vitamin D levels had the greatest risk of depression.
The researchers concluded that, where depression is concerned, vitamin D has a protective effect, explaining that it’s involved in the synthesis of neurotransmitters like serotonin and dopamine, which affect mood.
In addition, they found that achieving healthy vitamin D status through daily supplementation may lower the risk of developing depression: Ten of the meta-analyses revealed enhanced mood support for individuals taking vitamin D supplements compared to those on a placebo.
Studies in which participants consumed more than 5,000 IU of vitamin D daily or the intervention lasted less than or equal to 20 weeks saw the greatest effect in reducing symptoms of depression.
Given that more than 264 million people3 are affected by depression globally, according to a 2018 Lancet review, and that rates of depression rose during (and in the wake of) the COVID-19 pandemic, this study is an important step forward in our understanding of the condition.
Social connection, regular exercise, and stress management are often touted as powerful tools in the prevention of mental health challenges. This analysis shows that achieving and maintaining a healthy vitamin D status may be beneficial, too.
However, more research is needed. The researchers note that the study did not specifically look at certain types or severities of depression e.g., mild, moderate, or postpartum). What’s more, the effect of environmental factors on vitamin D levels—such as sunlight, latitude, and time outside—was not considered.