If I had clinically isolated syndrome with magnetic resonance imaging diagnostic of multiple sclerosis, I would take vitamin D 10,000 IU daily: Yes.

Proposal Strong epidemiologic evidence supports a role for vitamin D insufficiency as a risk factor for multiple sclerosis (MS), shown by increasing disease prevalence with increasing latitude, and inverse correlation with duration and intensity of ultraviolet B (UVB) sunlight exposure and vitamin D serum concentration. 1 Moreover, MS risk seems to decrease with migration from higher latitudes to lower ones. 2 The Nurses' Health Study II, in research focused on latitude and sunlight, demonstrated dietary vitamin D supplement use (estimated dose ≥400 IU/day) was associated with 40% less risk of MS development, compared to non users. 3 MS risk among study participants was reduced by approximately half, in women born to mothers with high vitamin D levels in breast milk or taking supplements during pregnancy, compared to women born to mothers whose intake had been low, suggesting that MS risk is related not only to recent vitamin D levels but also to levels present during childhood or in utero. A prospective nested case-control study among US military personnel demonstrated 41% decrease in MS risk in Caucasian individuals, for every 20 ng/ml increase in serum-measured vitamin D levels. 4 Likewise, in patients with pediatric-onset MS or clinically isolated syndrome (CIS) every 10 ng/ml increase in adjusted 25-hydroxyvitamin D3 level was associated with a one-third reduction in subsequent relapse rates. 5 There is accumulating data documenting the capacity of 1,25 dihydroxyvitamin D3 produced by macrophages, den-dritic cells (DCs), T cells and B cells, to contribute physiologically to autocrine and paracrine regulation of both innate and adaptive immune responses, via the vitamin D receptor (VDR) expressed in these types of cells. 6,7 1,25 dihydroxy-vitamin D3favors induction of DCs with tolerogenic properties , shaping T cell activation and development. In addition, 1,25 dihydroxyvitamin D3 can have a direct effect on T cells and B cells. On B cells, it inhibits the proliferation of memory B cells, plasma-cell differentiation and immunoglobulin production. Under appropriate conditions 1,25 dihydroxy-vitamin D3 inhibits the proliferation of CD4+ T cells favoring the development of IL-10 producing cells, and also inhibits pro-inflammatory, pathogenic Th1 and Th17 cells inducing differentiation of CD4+CD25+Foxp3+ regulatory T cells. Collectively, vitamin D affects the immune system at different levels, through varied mechanisms conferring an immunosuppressive effect on the whole which may ultimately be applied to treat autoimmune diseases such as MS. However, it is important to note that the majority of these immunological effects have only …