Article 25: 40% Reduction in MS Incidence with Vit D Supplementation

Background: A protective effect of vitamin D on risk of multiple sclerosis (MS) has been proposed, but no prospective studies have addressed this hypothesis.

Methods: Dietary vitamin D intake was examined directly in relation to risk of MS in two large cohorts of women: the Nurses? Health Study (NHS; 92,253 women followed from 1980 to 2000) and Nurses? Health Study II (NHS II; 95,310 women followed from 1991 to 2001). Diet was assessed at baseline and updated every 4 years thereafter. During the follow-up, 173 cases of MS with onset of symptoms after baseline were confirmed.

Results: The pooled age-adjusted relative risk (RR) comparing women in the highest quintile of total vitamin D intake at baseline with those in the lowest was 0.67 (95% CI _ 0.40 to 1.12; p for trend _ 0.03).

Intake of vitamin D from supplements was also inversely associated with risk of MS; the RR comparing women with intake of _400 IU/day with women with no supplemental vitamin D intake was 0.59 (95% CI _ 0.38 to 0.91; p for trend _ 0.006).

No association was found between vitamin D from food and MS incidence.

Conclusion: These results support a protective effect of vitamin D intake on risk of developing MS.

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