Vitamin D has long been known to be essential when it comes to keeping bones strong and boosting the immune system, but is there a link between vitamin D and depression? While the research findings are mixed, there’s a growing body of evidence that suggests a possible relationship between low circulating vitamin D levels in the blood and depression.

If you have depression, you’re not alone. Approximately 8.4% of U.S. adults experienced a major depressive episode in 2020, according to the National Institute for Mental Health. It can affect aspects of everyday life, from social interactions to sleep.

While treatments like talking therapies and medication are well established, the potential role of vitamin D is attracting attention. To help you understand more about the link between vitamin D and depression, we’ve sifted through the latest research to bring you everything you need to know about the role of vitamin D, the signs of vitamin D deficiency and depression, and practical steps to reach your vitamin D needs — including the best vitamin D supplement.

It is, however, important to consult a professional if you are suffering with your mental health and before making any significant changes to your dietary routine.

How does vitamin D work in the body?

According to the Office of Dietary Supplements, before the body can use it, vitamin D has to be activated. The liver converts it into calcidiol, which in turn becomes calcitriol in the kidneys.

“Vitamin D provides strength to bones, teeth and tissues by absorbing calcium and phosphorus in the body,” says says Sue-Ellen Anderson-Haynes, registered dietitian nutritionist and national spokesperson for the Academy of Nutrition and Dietetics. “It also regulates the amount of calcium in the blood.

“Vitamin D also plays a role in the immune system. Research shows that low vitamin D levels are associated with increased infection and autoimmune disease.”