Women who consume little vitamin D develop multiple sclerosis (MS) at a rate about 50 percent higher than those who get lots of the nutrient, researchers have found. MS is a neurodegenerative disease affecting 350,000 people in the United States.
Previous studies found that many MS patients are deficient in vitamin D, says Kassandra L. Munger, an epidemiologist at the Harvard School of Public Health. For instance, MS is more prevalent far from the equator, where less of the sun's ultraviolet light is available for people's bodies to make vitamin D. In an animal model of MS, Munger adds, vitamin D supplementation slowed the disease's progression.
Even so, it hasn't been known whether vitamin D deficiency precedes the onset of MS or results from the disease.
Munger and her colleagues assessed vitamin D intake from food and multivitamins in 187,563 women who participated in two large health studies lasting 10 and 20 years, respectively. Over the course of the studies