A review of vitamin D supplementation as disease-modifying therapy.

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS) and a major contributor to disability of young adults in western countries. MS prevalence is highest in areas with low vitamin D. Vitamin D is a fat-soluble compound with numerous physiologic responses, including immune regulation. An increasing volume of work suggests that lower levels of serum vitamin D are associated with an increased risk of MS and a more severe disease course. With the suggestion of a role in MS disease activity, increasing attention is being paid to the potential of using vitamin D as an add-on therapy to established MS disease-modifying therapies. Several preliminary studies have reported results which have shown some promise, but none has yet provided significant evidence of a clinically meaningful improvement. We review our recommendations for off-label supplementation in the context of these findings.