In the first prospective study to assess the relationship between vitamin D intake in women and the risk of developing multiple sclerosis (MS), researchers from the Harvard School of Public Health found that women with the highest intake of vitamin D through supplement use had a 40 percent lower risk of developing MS as compared with women who did not use supplements. The findings appear in the Jan. 13 issue of the journal Neurology.
More than 185,000 women from the Brigham and Women’s-based Nurses’ Health Study and Nurses’ Health Study II who were free of MS were selected for this research. The participants filled out dietary questionnaires every four years between 1980 and 1999 that assessed their vitamin D intake along with other dietary information. During the span of the study, 173 women developed MS. When compared with women who did not use vitamin supplements, those with the highest levels of vitamin D intake through supplements (400 IU per day or more) had a reduced risk of developing MS of 40 percent. There was no reduction in risk associated with vitamin D intake through food alone. Foods such as milk and fish are good sources of vitamin D and it is also manufactured by the body via exposure to the sun.
“These results are encouraging. We have suspected that vitamin D may play a role in reducing the risk of developing MS,” said Kassandra Munger, lead author of the study and a researcher in the Department of Nutrition at the Harvard School of Public Health.
Since the main source of vitamin D intake among women in this study was multivitamins, it is difficult to isolate the effects of vitamin D use from other vitamins. “However, none of the other vitamins was itself significantly associated with risk of MS after adjusting for total vitamin D intake or vitamin D from supplements,” Munger said.
“This is the first study to look at the role of dietary intake of vitamin D and risk of MS among women, and more research is needed,” said Munger.
Multiple sclerosis is a chronic disease of the central nervous system. The prevalence rate in the United States is higher for individuals who live above the 37th parallel, accounting for 110 to 140 cases per 100,000 people, compared with 60-80 cases per 100,000 for people living below the 37th parallel. Nationwide, there are an estimated 250,000 to 350,000 people with MS.