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.
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.
Two reviews of studies which have looked at Vitamin D supplementation found that Vitamin D was not effective at reducing depression symptoms. Many of the people who participated in these studies did not have a Vitamin D deficiency or a diagnosis of depression.
Only one study has looked into Vitamin D3 supplements for people diagnosed with depression. Most of the people in this study were also deficient in Vitamin D. The study found that adding Vitamin D supplements to antidepressants was better than antidepressants alone.
Overall, there is not much good quality evidence on Vitamin D for the treatment of depression. More studies of better quality are needed.
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.
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 no evidence to suggest that Vitamin D is an effective treatment for depression for the general population.
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.
Last reviewed and updated: 1 May 2019