Vitamin D Supplementation in Multiple Sclerosis

Vitamin D insufficiency has recently emerged as a risk factor for susceptibility to multiple sclerosis (MS). The investigator's observational data suggest that lower vitamin D levels in patients with relapsing-remitting MS are associated with a higher subsequent relapse rate. However, it is unknown if providing vitamin D supplementation to such patients leads to a reduction in the risk of an exacerbation. Historically, several nutritional supplements that appeared to be helpful in observational studies of various diseases did not demonstrate a benefit or were harmful in randomized trials. Further, a vitamin D response element was recently identified in the promoter region of Human Leukocyte Antigen (HLA)-DRB1\*15, the gene believed to be critical to initiating the autoimmune response in MS, and 1, 25-dihydroxyvitamin D3 increases the expression of the gene in vitro, suggesting that vitamin D supplementation could even be harmful in established MS. This is a randomized, double-blind trial of high- versus low-dose vitamin D3 supplementation as an add-on to glatiramer acetate in 172 patients with relapsing-remitting MS. Subjects will be randomized to 600 IU or 5000 IU of oral vitamin D3 daily for two years. A standardized brain MRI scan will be performed at baseline and at the end of the first and second years. The impact of high-dose vitamin D supplementation on the number of relapses, the number of new lesions on brain MRI, and the change in brain volume will be assessed. Establishing these associations will have major implications for the treatment of patients with MS throughout the world and will provide rationale for further investigations of the role of vitamin D in the immunopathogenesis of MS, possibly leading to the identification of new therapeutic targets.