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Can Vitamin D Help with Seasonal Affective Disorder?


Many people feel down in the winter months from the lack of sunlight during the short days. Of course, sunlight is a major source of vitamin D. Researchers from Loyola University Chicago Marcella Neihoff School of Nursing (MNSON) have set out to see if dietary sources of vitamin D have the same effect on depression and mood.

Loyola is currently enrolling women in this clinical trial. In order to enter the study, they must be 18 to 70 years of age, signs of depression and no other major medical illness. Because the researchers will also evaluate the relationship between vitamin D, depression and diabetes, the women enrolled in the study will need to have stable type 2 diabetes. Eighty women will be selected and given a weekly dose of 50,000 IU of vitamin D for a period of six months.

Vitamin D has had much research lately into its positive effects on health, or rather it contribution to chronic illnesses when a person is deficient in the nutrient. In diabetes, for example, diabetes supplementation in those deficient may decrease insulin resistance.

Vitamin D has been used in the study of depression since 1989 when Professor Walter Sumpf of the University of North Carolina wrote a paper on bright light, vitamin D and depression and the results have been conflicting.

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Researchers in Boston found no effect from supplementation of 400 IU of vitamin D2 on women suffering from seasonal mood changes in 1993. In 1998, Australian researchers found that a higher dose of a different form of vitamin D, 800 IU of cholecalciferol, did enhance mood in late winter months. More recently, German scientists found that depressed subjects had a slightly lower blood level of 25(OH)D than that of healthy controls.

Vitamin D is a fat-soluble vitamin essential for promoting calcium absorption to maintain bone mineralization. Without adequate vitamin D, bones can become thin, brittle, or mis-shapen. Vitamin D is also involved in immune function, neuromuscular function, and reduction of inflammation.

Some research indicates that dietary intake and sunlight may not be sufficient to maintain body levels of vitamin D and therefore more Americans need supplementation. Adequate vitamin D levels are assessed by measuring the body levels of 25-hydroxyvitamin D or 25(OH)D. Currently, blood levels greater than 37.5 nmol/L are considered adequate, although some researchers believe this to be too low.

It will be interesting to learn what the study from Loyola will find. The National Vitamin D Council has this to say regarding vitamin D and depression:
“Vitamin D may help major depression. It is too early to say. To know for sure, patients with severe major depression would have to have baseline 25(OH)D blood levels, be treated with doses of vitamin D adequate to raise their levels to at least 35 ng/mL for several months and be compared to a normal control group treated with placebo. No one has ever published such a study.”

Until then, the agency recommends that if you suffer from depression or seasonal affective disorder, do not self-treat the condition with vitamin D. Have blood levels tested, and follow the advice of your physician.



Hopefully they will test the 25(OH)D levels before, during and after the study as reaching any conclusions just based on the dose is not a sound way to judge the effect.