Vitamin D helps keep bones and immune cells healthy. Vitamin D is found in oily fish such as salmon and tuna. Small amounts can also be found in calcium rich foods. In some countries it is added to food. Your body 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 vitamin D in your blood.
Some researchers believe that Vitamin D is important in brain processes that can affect depression.
Some studies have found that Vitamin D deficiency is associated with depression. People who have dark skin are at a higher risk of Vitamin D deficiency. People who do not get enough time in the sun are also at a higher risk of becoming deficient in Vitamin D. This includes people who live in areas with little sunlight, do not go out in the sun and/or keep their skin covered.
There is very little scientific evidence on Vitamin D for the treatment of depression. More studies of better quality are needed.
A systematic review found no overall benefit of Vitamin D. Most of the studies included people at risk of developing depression.
Only one study has looked into Vitamin D3 supplements for people diagnosed with depression. Most of the people in this study were deficient in Vitamin D. The study found that adding Vitamin D supplements to antidepressants was better than antidepressants alone.
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 stored in the body. Taking too much may lead to a rare condition that can cause kidney damage. Some Vitamin D supplements also contain calcium. Taking too many of these can lead to a build-up of calcium. This may cause nausea, vomiting, loss of appetite and muscle weakness.
One person in the study who was taking Vitamin D and antidepressants reported severe anxiety after 2 weeks. The study did not report any other side effects. However, it is not clear whether the study investigated negative effects. More research is needed on the possible side effects of Vitamin D.
Vitamins are present naturally in food. 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.
Adequate Vitamin D levels are important for maintaining health. It is thought that Vitamin D deficiency might be linked to depression. 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: 16 March 2015