Vitamin D and multiple sclerosis
A role of adequate vitamin D nutrition in the prevention of multiple sclerosis (MS) was originally proposed to explain the geographical distribution of MS, but only recently has the relation between various measures of vitamin D (eg, sun exposure, dietary sources, etc) and risk of developing MS been rigorously investigated.
Overall, the results of these studies support a protective effect of vitamin D, but there are uncertainties and many unanswered questions, including how vitamin D exerts a protective effect, how genetic variations modify the effect, and whether vitamin D can influence the course of MS progression. Ascherio A.; Munger K.L.; Simon K.C. Lancet Neurol. 2010 Jun; 9(6):599-612.