More than 185,000 women from the Brigham and Women’s-based Nurses’ Health Study and Nurses’ Health Study II, who were free of multiple sclerosis (MS), were selected for a research study. 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 to 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. The findings appeared in the Jan. 13, 2004 issue of the journal Neurology.