Abstract & Commentary
Synopsis: High vitamin D intake is associated with lower incidence of MS.
Source: Munger KL, et al. Vitamin D intake and incidence of multiple sclerosis. Neurology. 2004;62:60-65.
Munger and colleagues reviewed a database of 187,563 women enrolled in the Nurses’ Health Study, which longitudinally surveyed participants aged 25-55. There were 173 women with probable or definite multiple sclerosis (MS). Vitamin D intake was determined through the study questionnaire and 4 1-week diet records. Blood vitamin D levels were tested and compared with other variables that might predispose to disease, such as latitude of birth and early childhood and smoking (Munger et al had reported an increased risk of MS among nurses who smoked).
Women whose vitamin D intake was approximately 400 IU/day or more from supplements and food or from supplements alone had a 40% lower risk of developing MS than women who did not take the supplements.
Comment by Brian R. Apatoff, MD
The incidence of MS worldwide is higher in northern latitudes and lower in the equatorial regions. In addition to recognized genetic and environmental/infectious factors, one protective variable of southern climates might be increased vitamin D production from sunlight exposure. Vitamin D is now also commonly supplemented in multivitamins or with calcium, usually in postmenopausal women at higher risk for osteoporosis.
While the current study indicates a preventative role for vitamin D in reducing the risk of acquiring MS, it does not address whether vitamin D supplements can alter the course of existing MS or if vitamin D has similar preventative benefits in men. Since first-degree family members of persons with MS have approximately a 20-fold increased risk of developing MS, is it reasonable for at-risk groups to be taking vitamin D supplements?
In general, MS patients may be at higher risk of osteopenia from exposure to corticosteroids and a more sedentary lifestyle. It is reasonable to have patients on a vitamin D supplement for this health benefit alone.
More needs to be understood about the immune mechanisms of MS and the immunomodulatory effects of vitamin D for broader recommendations.
Dr. Apatoff is Associate Professor of Neurology, New York Presbyterian Hospital-Cornell Campus.