Is there a link between vitamin D and depression?

couple walking their dog along the beach as the sun sets
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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 (opens in new tab). 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?

First, let’s get under the surface of how vitamin D works. When UV rays from the sun hit the skin, they stimulate vitamin D production. This is why it’s called the ‘sunshine vitamin’.

According to the Office of Dietary Supplements (opens in new tab), 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 (opens in new tab), 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.”

Sue-Ellen Anderson-Haynes, RDN
Sue-Ellen Anderson-Haynes

Anderson-Haynes is the founder and owner of a private practice specializing in holistic health and wellness for girls and women and is the co-founder of an app that helps to connect registered dietitian nutritionists to clients based on culture. She’s certified in adult weight management, a certified personal trainer and a certified diabetes care and education specialist. Anderson-Haynes is a graduate of the University of Florida and earned a master’s degree from Andrews University.

What’s the link between vitamin D and depression?

Research findings have sparked interest in the link between vitamin D and depression. “Recent studies show that low vitamin D levels are often seen in those diagnosed with clinical depression — there is an inverse relationship,” explains Anderson-Haynes. 

One review, published in the British Journal of Psychiatry (opens in new tab), examined data from over 30 000 participants and found that people with depression tended to have lower vitamin D levels. While we don’t fully understand the nature of the link between vitamin D and depression, there are several possible explanations, though none have been proven.

One potential theory is that vitamin D deficiency causes depression. If that were the case, you would expect supplementation to alleviate symptoms. But studies show mixed results. One review, published in CNS Drugs (opens in new tab), found that supplementation with vitamin D eased symptoms in people with depression, with the impact being more pronounced in people with major depressive disorder. However, another study in BMC Research Notes (opens in new tab) found vitamin D made no significant difference compared to a placebo. 

Young, happy woman taking vitamin D

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Another review (opens in new tab) pointed out that the relationship could work the opposite way. People with depression may be at increased risk of vitamin D deficiency because they are more likely to withdraw from social activity and spend less time outside. 

There are other theories about the link between vitamin D and depression. One review, published in the Indian Journal of Psychological Medicine (opens in new tab), notes there are many vitamin D receptors in brain areas known to play a role in mood. These include the prefrontal and cingulate cortices. In addition, vitamin D regulates the hypothalamic-pituitary-adrenal axis, which influences mood. 

The same review (opens in new tab) suggests another hypothesis that could be related to the immune system. Depression is correlated with higher levels of chronic inflammation, which happens when the immune response is triggered unnecessarily. Meanwhile, vitamin D is known to support immunity and have anti-inflammatory effects. 

Symptoms of vitamin D deficiency and depression

To complicate matters, the symptoms of vitamin D deficiency and depression have a degree of overlap. 

According to the National Institute of Mental Health (opens in new tab), symptoms of depression include:

  • Persistent sad or anxious mood
  • Feelings of hopelessness
  • Decreased energy and fatigue
  • Aches or pains without a clear physical cause that do not ease with treatment
  • Loss of interest or pleasure in hobbies and activities
  • Thoughts of death or suicide

Woman with depression sitting on couch

(Image credit: Getty Images)

According to Anderson-Haynes, early signs of a vitamin D deficiency are:

  • Tiredness
  • Cramps
  • Muscle weakness

The Cleveland Clinic (opens in new tab) suggests that mood changes, including symptoms of depression, could be a sign of a vitamin D deficiency. 

Over time, the impact on bones and teeth could lead to rickets in children and soft bones or osteomalacia in adults. 

Speak to a doctor if you’re concerned about any of these symptoms. 

Sources of vitamin D

The NIH (opens in new tab) notes that foods rich in vitamin D are in short supply. 

Depending on how much you eat, foods such as orange juice, plant-based milk fortified with vitamin D, mushrooms treated with UV, sardines, and egg yolks may provide you with the intake you need,” says Anderson-Haynes. 

“Regular sun exposure is important in improving your vitamin D status. Those with more melanin [darker skin] need longer sun exposure since it is more difficult for the rays to penetrate the skin.”

Experts recommend sunblock to protect against skin cancer while outside for prolonged periods. This makes it tricky to get sufficient vitamin D from sunlight, particularly in winter.

Be aware that specific groups are more at risk of developing a vitamin D deficiency. According to the Office of Dietary Supplements (opens in new tab), this includes people with darker skin, older adults, and people with limited sun exposure.

A doctor will be able to perform a blood test check your levels of vitamin D. From here, they will be able to advise the best course of action.

This article is for informational purposes only and is not meant to offer medical advice.

Louise Bond is a UK-based writer specializing in health and wellbeing. She has over eight years of experience in management within health and care and brings this passion and expertise to her writing. Louise has been published in The Guardian, Planet Mindful and Psychreg among others. She is at her happiest when she is out in nature, whether that’s on an invigorating hike or pottering in the garden.