Diet as a Risk Factor for MS: The Evidence

By Connie Brichford

Medically reviewed by Cynthia Haines, MD

Doctors and other health-care professionals recommend a healthy diet to all their patients, and especially to people with a chronic illness like multiple sclerosis. The purpose of such a recommendation is to promote a healthy lifestyle, rather than trying to prevent any one specific disease. And, in the case of multiple sclerosis, with the exception of including sufficient levels of vitamin D, not a lot of evidence is available to help us understand how diet might play a role in the development of the disease.

Globally, multiple sclerosis is most prevalent in southern Australia, northern Europe, and North America: the farther from the equator, the higher the incidence. And this holds true for the United States as well: Incidence of multiple sclerosis is lower in the southern states and higher in the northern states. On the other hand, there is also some speculation about the role of high-fat diets or high-sugar diets. This is based on the idea that people who live in areas of higher incidence tend to eat different foods from people who live in areas with lower.

Diet as a Risk Factor for MS: The Evidence
While the jury is out on a definite link between diet and multiple sclerosis, there is a great deal of evidence to support link between multiple sclerosis and a vitamin D deficiency, and the number of studies is growing. But while it is clear that there is an association between the two, it remains uncertain just how vitamin D deficiency affects multiple sclerosis or its development.

MS and Diet: Vitamin D
A study of active-duty military personnel found that people with higher levels of vitamin D in their blood were less likely to develop multiple sclerosis than those with lower levels of vitamin D, although the finding applied to whites only, not blacks or Hispanics.

“Many studies have given us a good link between vitamin D status and immune function in MS,” says Heather E. Hanwell, a doctoral candidate in nutritional sciences at the University of Toronto and author of a recent study of the affect of vitamin D on MS. “We wanted to see whether vitamin D status was lower in children who had their first demyelinating event [shedding of the myelin sheath, the protective covering of the nerves] and were subsequently diagnosed with MS.” In Hanwell’s study, presented at the World Congress on Treatment and Research in Multiple Sclerosis, in Montreal, vitamin D levels were significantly lower in children diagnosed with MS. “Another way of looking at it is that as vitamin D status increased, children had a lower risk of being diagnosed,” she says.