Vitamin D and Depression: Is There A Link?

Vitamin D is a secosteroid responsible for regulating calcium in the body, and may have other health effects as well, including reducing the risk of cancer and heart disease. There may also be a link between vitamin D and depression, although whether this is a strong link or not remains to be seen.

There is a well known form of depression called seasonal affective disorder, which involves annual bouts of depression in response to seasonal changes, either in winter or summer, generally. The best treatment for this is light therapy. Exposure to UV light for periodic sessions can help SAD sufferers. Since vitamin D is acquired through exposure to UV light, does it play a role in depression?

Several studies have attempted to find out. A 1992 study published in Psychiatry Research found that vitamin D supplementation on 250 women with SAD did not have any affect on their condition. A 1998 study published in Psychopharmacology found a similar effect, on volunteers receiving up to 800 IU per day of vitamin D3.

And a further study in 1999 found that a single dose of 100,000 IU (over 50,000 IU of sustained use is toxic; one time doses are not) of vitamin D3 provided better treatment for SAD than light therapy.

And yet further evidence is to be found in the increase in depression over the 20th Century. Over this time, people have stopped working outdoors as much, sunblock was invented, people were encouraged to not get too much sunlight because of skin cancer, and so on. If vitamin D plays a role in depression, then depression rates should have skyrocketed during this period. Indeed this is the case.

So, clearly vitamin D plays some role in depression, but whether it’s good as a treatment or not remains to be seen. This would requires a large scale study on the direct connection between the two, as correlation does not always mean causation. To date, this has not been performed.