Women who take vitamin D supplements are 40% less likely to develop multiple sclerosis (MS) than women who do not take supplements, according to a study in the January 13 Neurology. “Because the number of cases of MS increases the farther you get from the equator, one hypothesis has been that sunlight exposure and high levels of vitamin D may reduce the risk of MS,” said study author Kassandra L. Munger, MSc, of the Department of Nutrition at Harvard School of Public Health in Boston. “This is the first prospective study to look at this question. “These results need to be confirmed with additional research, but it’s exciting to think that something as simple as taking a multivitamin could reduce your risk of developing MS.”

A PROTECTIVE EFFECT

The researchers examined data from two large studies involving women: the 20-year Nurses’ Health Study and the 10-year Nurses’ Health Study II. The women’s diets and multivitamin supplement use were assessed at study baseline and then again every four years. Results from women with MS symptoms before study initiation were not included. There were 187,563 women in the study. Of those, 173 women developed MS during the course of the study.

The women were divided into groups based on vitamin D use. Those with the highest intake of vitamin D from supplements (400 IU or more per day) were 40% less likely to develop MS than were those who used no supplements.

The risk of MS was also lower for those with high intake from both supplements and food than for those receiving no vitamin D from supplementation or diet. However, those whose intake of vitamin D was from food only did not have any lesser risk of MS.

The researchers also analyzed the data while adjusting for smoking and latitude at birth, but the results did not change.

D, ONE AND ONLY

Since supplemental vitamin D intake was mainly from multivitamins, it is difficult to isolate the effects of vitamin D from the potential effects of the other vitamins, admitted Ms. Munger. “However, none of these vitamins was itself significantly associated with risk of MS after adjusting for total vitamin D intake or vitamin D from supplements,” she said.

Earlier research also points to the role of vitamin D in MS. Studies with mice with experimental autoimmune encephalomyelitis, an autoimmune disease in animals that is used as a model of MS, have shown that vitamin D supplements can prevent or favorably affect the course of the disease. Other studies have shown that people with MS often have fluctuating and often insufficient levels of vitamin D, and that periods of low vitamin D occur before times of high disease activity and periods of high vitamin D precede times of low disease activity. Ms. Munger said that future prospective studies should measure the levels of vitamin D in the blood prior to the onset of MS.

NR

—Jean McCann

Munger KL, Zhang SM, O’Reilly E, et al. Vitamin D intake and incidence of multiple sclerosis. Neurology. 2004; 62:60-65.
Bowling AC, Stewart TM. Current complementary and alternative therapies for multiple sclerosis. Curr Treat Options Neurol. 2003;5:55-68.
Garcion E, Sindji L, Nataf S, et al. Treatment of experimental autoimmune encephalomyelitis in rat by 1,25-dihydroxyvitamin D3 leads to early effects within the central nervous system. Acta Neuropathol (Berl). 2003;105: 438-448.
Mahon BD, Gordon SA, Cruz J, et al. Cytokine profile in patients with multiple sclerosis following vitamin D supplementation. J Neuroimmunol. 2003;134:128-132.

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