Why is There More MS in the North?

According to an analysis of data from the Nurse’s Health Study published in the Jan. 13, 2004 issue of Neurology, vitamin D may have a protective effect against multiple sclerosis (MS). Women without multiple sclerosis symptoms completed questionnaires on diet and use of multivitamin supplements. Of 187,563 women, 173 women developed MS during the study. Women who took 400 IU or more of vitamin D per day from vitamin supplements were 40% less likely to develop multiple sclerosis than those who used no supplements.  There have been earlier studies on mice supporting this idea. Also, some researchers have linked low vitamin D levels to multiple sclerosis.

Periods of exacerbation in MS patients have been linked to periods of low vitamin D levels and periods of remission have been linked to high vitamin D levels. Because the incidence of multiple sclerosis increases as you get farther from the equator, some scientists think that sunlight exposure and high levels of vitamin D may reduce the risk of multiple sclerosis.