According to John Cannell, MD, an expert on vitamin D and the staff psychiatrist at a California psychiatric hospital, Vitamin D deficiency contributes to many mood problems. "About 90% of patients in my hospital are vitamin D deficient," says Dr. Cannell, "and I put them on a vitamin D regimen, and it does improve their mood disorders,"
In a separate study lasting 3 years, the risk of depression was found to be 21% lower among women (aged 50 to 79) who reported total daily vitamin D intake (from foods and supplements) of at least 800 IU compared to women with intake of less than 100 IU. Excluding women with evidence of depression at the beginning of the study, a 20% lower risk of depression was seen with intake of just 400 IU or more per day. However, further analyses showed no reduction in the risk of depression resulting from vitamin D supplements alone. The reductions were only associated with higher vitamin D intake from foods.