The study is published in the Journal of the American Medical Association.
“If confirmed, this finding suggests that many cases of MS could be prevented by increasing vitamin D levels” said Alberto Ascherio, who led the study and is Associate Professor of Nutrition and Epidemiology at Harvard School of Public Health. Although the results are encouraging, he emphasized the need to confirm the results and to prove that high vitamin D levels actually cause lower risk of developing MS. They could just be linked through some other means. There is not enough evidence to suggest that people should start taking vitamin D supplements, he says.
The researchers used blood samples from the Department of Defense’s Serum Repository which holds samples of more than 7 million military personnel. They identified 257 people with MS from the Army and Navy physical disability databases for 1992 through 2004. They also checked against medical records. They took the average level of 25-hydroxyvitamin D in at least two samples in each case. In the case of those with MS, the blood samples predated the onset of symptoms. They also analysed the data in ethnic/racial groups: white, Hispanic and black.
The study found that among whites the risk of developing MS significantly decreased with increasing levels of vitamin D in their blood. For instance, those people in the top 20 per cent of vitamin D concentration bore a 62 per cent lower risk of MS compared to the people in the lowest 20 per cent. The relation between high vitamin D and low MS risk was found to be particularly strong in the under 20s.
The researchers said that the level of vitamin D they found in the high range that appeared to give protection against MS were within safe levels, and suggested that higher levels of vitamin D could be good for protecting against osteoporosis and other chronic diseases.
The researchers could not find any significant links between vitamin D levels and MS risk for Hispanic and black people, although they had significantly lower levels of vitamin D in their blood. This could be because of the small numbers involved.
The study is in line with a growing body of evidence that shows how important vitamin D is to the immune system, where it helps to control autoimmune reactions.
Multiple Sclerosis affects the central nervous system and is a progressive, degenerative disease. Some 350,000 people in the US have MS, and another 2 million people worldwide. MS is most common in young adults, and in women more than men.
Vitamin D, unlike many other vitamins, can be manufactured in the body, as long as there is enough exposure to sunlight. The further away from the tropics you are, the more likely it is that you will not get enough sun during the dark months to make your daily requirement of vitamin D. This is why you should include food rich in vitamin D in your diet in winter, such as fatty fish, shitake mushrooms (good source for vegans), eggs and cod liver oil.
Many modern processed foods are now fortified with vitamin D, for instance milk. Fortification was introduced to prevent rickets, a bone condition where the legs bow outwards.
“Serum 25-Hydroxyvitamin D Levels and Risk of Multiple Sclerosis.”
Kassandra L. Munger, MSc; Lynn I. Levin, PhD, MPH; Bruce W. Hollis, PhD; Noel S. Howard, MD; Alberto Ascherio, MD, DrPH.
Written by: Catharine Paddock
Writer: Medical News Today