Vitamin D

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Question mark: This treatment has not been properly researched. It is not possible to say whether they are useful or not.


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What is it?

Vitamin D helps keep bones and immune cells healthy. Vitamin D is found in oily fish such as salmon and tuna, and in small amounts in calcium rich foods. In some countries it is added to certain food products. Your body also makes vitamin D when exposed to direct sunlight.

Vitamin D comes in two forms: Vitamin D2 (ergocalciferol) and Vitamin D3 (cholecalciferol). Vitamin D3 may be more helpful in increasing the levels of vitamin D in your blood.

How does it work?

Some studies have found that Vitamin D deficiency is associated with symptoms of depression, but it is not clear why this association exists. Some researchers believe that Vitamin D is important in brain processes that can affect depression.

Some people are at a higher risk of developing a Vitamin D deficiency. This includes people who have dark skin, people who do not get enough time in the sun, people who live in areas with little sunlight, and people who do not get much exposure to sunlight.

Is it effective?

A review of high quality studies which have looked at Vitamin D supplementation in adults with depression showed mixed results. The people who participated in these studies all had a diagnosis of depression but did not necessarily have a vitamin D deficiency. Overall the review found there is not strong evidence that Vitamin D supplementation is effective for the treatment of depression.

A broader review, which included studies where participants may not have had a depression diagnosis, found that supplementation with Vitamin D is effective for reducing depression symptoms. The review found that there was variability in how much vitamin D was used in the studies. There were also differences in whether participants had a deficiency in vitamin D.

Some studies have found that people with lower levels of Vitamin D benefit more from supplementation with Vitamin D. Other studies have found that the association between Vitamin D levels and depression symptoms may be stronger in younger adults aged less than 50 years.

Conclusions about whether Vitamin D is an effective treatment for depression are mixed. More high quality studies with different groups of people are required.

Are there any disadvantages?

Vitamin D is stored in the body an taking too much may lead to a rare condition that can cause kidney damage. Some Vitamin D supplements also contain calcium, and taking too much calcium may cause nausea, vomiting, loss of appetite and muscle weakness.

Some vitamin supplements can be harmful or ineffective if you take the wrong dose. Talk to your health care professional if you are thinking of taking supplements.

Where do you get it?

Vitamin D is found in oily fish such as salmon and tuna, and in small amounts in calcium rich foods. You can buy vitamin supplements in health food shops, supermarkets or from chemists. They usually come in tablet, capsule or powder form. Vitamins may also be given as an injection by a doctor.


Vitamin D supplements might be helpful for people who have a Vitamin D deficiency, but there is mixed evidence about whether Vitamin D is an effective treatment for depression, and if so, for which groups of people..

If you have depression, ask your doctor about whether it would be helpful for you to have a Vitamin D blood test. If your levels are low, your doctor will help you work out the best treatment.

Key references

  • Guzek D, Kołota A, Lachowicz K, Skolmowska D, Stachoń M, Głąbska D. Effect of Vitamin D Supplementation on Depression in Adults: A Systematic Review of Randomized Controlled Trials (RCTs). Nutrients. 2023; 15(4):951.
  • Ma J, Li K. Negative Association between Serum Vitamin D Levels and Depression in a Young Adult US Population: A Cross-Sectional Study of NHANES 2007-2018. Nutrients. 2023; 15(13).
  • Musazadeh V, Keramati M, Ghalichi F, Kavyani Z, Ghoreishi Z, Alras KA, et al. Vitamin D protects against depression: Evidence from an umbrella meta-analysis on interventional and observational meta-analyses. Pharmacological Research. 2023; 187:106605.
  • Rahman ST, Waterhouse M, Romero BD, Baxter C, English DR, Almeida OP, et al. Effect of vitamin D supplementation on depression in older Australian adults. International Journal of Geriatric Psychiatry. 2023; 38(1):e5847.

Last reviewed and updated: 7 August 2023