Whether low levels of vitamin Dcause depression, worsen it, or are a symptom of the underlying depression is not fully understood. "There is no solid proof that vitamin D deficiency causes depression," says researcher Sonal Pathak, MD. She is an endocrinologist at Bay Health Endocrinology in Dover, Del. "Large studies are clearly needed."
Her findings were presented at The Endocrine Society's 94th Annual Meeting in Houston.
Pathak's study included three women aged 42 to 66 with depression, all of whom were taking antidepressants. The women were also being treated for type 2 diabetes or an underactive thyroid gland.
All three were deficient in vitamin D, with levels that ranged from 8.9 to 14.5 nanograms per milliliter of blood (ng/mL). Levels below 21 ng/mL are considered vitamin D deficient. Normal vitamin D levels are above 30 ng/mL, according to guidelines set by The Endocrine Society.
The women received vitamin D therapy for eight to 12 weeks to replenish their blood levels. After treatment, their levels increased to 32 to 38 ng/mL. The women also reported corresponding improvements in symptoms of depression following vitamin D therapy. One woman's depression score changed from one indicating severe depression to mild depression. Another woman's score improved to a level suggesting she had just minimal symptoms of depression.
Vitamin D is called the sunshine vitamin because our bodies produce it when exposed to sunlight. Vitamin D is also added to milk and other foods, and is available in small amounts in fatty fish like tuna, salmon, and mackerel; beef liver, cheese, and egg yolks. It can be hard to get as much as we need from our diets, which is why supplements are often needed.
The Institute of Medicine recently raised the recommended daily intake to 600 IU for people aged 1-70 and to 800 IU for adults older than 70. Other groups set the bar even higher.