Research has speculated that vitamin D could be linked to depression and other mental disorders. However, some studies have found a vitamin D depression link, others have found that there is no clear link.
People with depression are often low in vitamin D, and although some studies show a link between low levels of vitamin D and depression, research has not been able to shown clearly whether low vitamin D levels cause depression, or whether low vitamin D levels may be secondary to depression.
Low levels of vitamin D are also linked to seasonal affective disorder or SAD, where people get down in the dumps in the dark, short winter days because of lack of sunlight. Seasonal affective disorder is prevalent when vitamin D stores are typically low. Some studies suggest that vitamin D supplements can help with seasonal affective disorder. In one randomized controlled trial, a group of 15 subjects with seasonal affective disorder received either 100,000 I.U. of vitamin D or phototherapy, a broad-spectrum light therapy. All subjects receiving vitamin D showed improvement in depression scale scores, while those who had phototherapy showed no significant change in depression scale scores. The study concluded that Vitamin D could be an effective treatment for seasonal affective disorder.
There is also a strong link between low vitamin D levels and postnatal depression.
About 13 % of elderly people have depression symptoms. Elderly people with low vitamin D levels and high levels of a hormone from the parathyroid glands could have a greater risk of depression.
Poor vitamin D status brings about a rise in serum parathyroid hormone levels. Over active parathyroid glands often cause depression symptoms that go away following treatment.
In another study, researchers recruited in excess of 3,000 people and analyzed vitamin D levels within the blood. Then they conducted a survey with all the people to look at the presence of depression symptoms. The study found there was no clear vitamin D depression link, and that other studies have given mixed outcomes and therefore more research is still needed.
A recent paper has found that there is not enough proof to support vitamin D supplements in people with depression, but should be considered in those who are at risk of low vitamin D levels.
Reference 1 for: The Vitamin D Depression Association
Reference 2 for: The Vitamin D Depression Association
Reference 3 for: The Vitamin D Depression Association
Reference 4 for: The Vitamin D Depression Association