Vitamin D and depression: are the two connected?

Depression is a widespread and increasingly common condition. But 70 years after the release of the first antidepressant drugs, science still hasn’t gotten closer to a magic bullet—or even to fully understanding what causes depression.

Research has recently turned to whether certain vitamins and supplements can have an effect on depressive symptoms and mood disorders. One of them is vitamin D.

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Potential trivia answer first: vitamin D isn’t actually a vitamin. Technically, it’s a prohormone—something the body makes and converts to a hormone—that has a role in several important bodily processes.

Known as the “sunshine vitamin,” vitamin D is made by the body as a response to sun exposure. When sunlight hits the skin, the body produces a substance that the liver and kidneys convert to forms usable by various organs and systems.

Vitamin D seems to have several benefits including helping bones stay strong and preventing osteoporosis, boosting the immune system, reducing the risk of heart disease, and providing protection from several cancers (including breast and colon). It also assists the body in regulating insulin, which could reduce the risk of diabetes (Vacek, 2012).

Vitamin D is found in a variety of foods, including eggs and milk. But much of the world’s population is deficient in vitamin D—up to 1 billion people worldwide, and 40% of Americans (Parva, 2018).

Can low levels of vitamin D in your body impact your mental health? The science is kind of up in the air.

There is a slight link between a low bodily level of vitamin D and depression, but it’s not clear whether a low level of vitamin D causes depression. It’s also unclear whether supplementation can help relieve depressive symptoms (Geng, 2019).

Many studies have found lower-than-optimal levels of vitamin D to be associated with depression. A meta-analysis of studies involving more than 31,000 people found that low vitamin D levels were found in depressed people compared to a control group (Anglin, 2013; von Känel, 2015).

But is the solution just taking more vitamin D? A 2020 review found that vitamin D supplementation had a positive effect on patients with major depressive disorder. However, if you’re experiencing only mild symptoms of depression, just adding a vitamin D supplement to your daily routine might not perk you up (Cheng, 2020).

A 2015 meta-analysis of studies involving 5,000 people and found that vitamin D supplementation had “no significant reduction in depression.” But researchers noted the studies examined focused on people with low levels of depression” who had adequate vitamin D levels (Gowda, 2015).

Researchers aren’t sure why vitamin D might have an effect on depression, but they have some theories. Three areas in the brain that help regulate emotions—the prefrontal cortex, hypothalamus, and substantia nigra—have vitamin D receptors.

Vitamin D also helps regulate levels of serotonin, and lower levels of vitamin D might lead to lower concentrations of serotonin in the brain (several antidepressant medications aim to alleviate depression by boosting serotonin levels).

Vitamin D also helps the brain dispense the natural chemicals dopamine and norepinephrine; low levels of both have been observed in people with depression (Pittampalli, 2018).

Good sources of vitamin D in food include fatty fish (such as salmon and tuna), fish oil, fortified milk, eggs, and fortified breakfast cereals.

You could also take a vitamin D supplement. The Office of Dietary Supplements recommends a daily intake of vitamin D of 600 IU for adults up to age 69 and 800 IU for adults 70 and older. The tolerable upper daily limit is 4,000 IU (100 mcg). Be careful when taking vitamin D supplements—vitamin D toxicity is possible (NIH, n.d.).

If you’re concerned that you might have a low level of vitamin D, talk with your healthcare provider, who can check your vitamin D status with a simple blood test.

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Current version

July 06, 2020

Written by

Michael Martin

Fact checked by

Mike Bohl, MD, MPH, ALM

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About the medical reviewer

Mike Bohl, MD, MPH, ALM

Dr. Mike is a licensed physician and a former Director, Medical Content & Education at Ro.