During the study -- published in the Journal of the American Medical Association -- the researchers pored through more than 7 million serum samples from U.S. military personnel, and found 257 had developed the disorder. The samples with MS were analyzed and their vitamin D levels compared to a control group of unaffected military personnel from the same grouping.
The white people studied showed a proportional drop in MS risk with an increased vitamin D level, with the people in the top fifth of the high-vitamin-D sample showing a 62 percent reduced risk. The researchers said this suggested an increased vitamin D intake might prevent many cases of MS.
The black and Hispanic people studied showed no drop in MS risk regardless of their vitamin D levels, but lead researcher Alberto Ascherio said this could be because both groups had overall lower vitamin D levels or because there were so few blacks and Hispanics in the sampling.
According to Nicholas LaRocca of the National Multiple Sclerosis Society, which helped fund the study, the findings were promising, but it was too soon to begin recommending vitamin D supplements as a way to prevent MS.
Multiple sclerosis is an as-yet-incurable disease marked by disrupted communication between the brain and the body, sometimes leading to paralysis, and affects about 2 million people worldwide. Some experts believe it to be an autoimmune disorder in which the immune system attacks its own body.
Vitamin D has been shown in previous studies to reduce the risk of certain types of cancer and promotes calcium absorption, subsequently increasing the strength of bones. Vitamin D deficiency has been shown to lead to osteoporosis, rickets and a host of other health problems. The hormone can be introduced into the body through fatty fish such as salmon, or produced in the skin through sensible sun exposure, leading to its nickname, "the sunshine vitamin."