There is evidence that Vitamin D Deficiency is associated with Multiple sclerosis, an autoimmune disease. Vitamin D supplementation is recommended to protect against progression of MS. In a study published in 2013, in JAMA Neurology the researchers found that higher serum 25(OH)D levels in the first 12 months predicted reduced MS activity and a slower rate of MS progression. By the end of the follow-up at 5 years, participants with serum 25(OH)D concentrations of at least 50 nmol/L (20-ng/mL, a moderate level) had significantly fewer new active lesions, a slower increase in brain lesion volume, lower loss of brain volume, and lower disability than those with serum 25(OH)D concentrations below 50 nmol/L. These results suggest that vitamin D has a protective effect on the disease process underlying MS. (https://www.nih.gov/news-events/nih-research-matters/vitamin-d-levels-predict-multiple-sclerosis-progression).
In a new study (below) published in October 2016, the authors report how the active form of Vitamin D helps to reduce the inflammatory factors that destroy the myelination of the central nervous system and also helps restore a healthy immune function preventing the destructive demyelination of nerves.
Vitamin D modulates different IL-17-secreting T cell subsets in multiple sclerosis patients
Vitamin D deficiency is an environmental risk factor for MS, a Th17 cell-mediated autoimmune disease that results in demyelination in the CNS. Therefore, we aimed to evaluate the ability of in vitro 1,25(OH)2D in modulating different Th17 cell subsets in MS patients in remission phase. In the present study, the production of Th17-related cytokines (IL-1β, IL-6, IL-17, IL-22), as well as GM-CSF, was significantly higher in cell cultures from MS patients than in healthy subjects (HS). The 1,25(OH)2D reduced all pro-inflammatory cytokines essayed, mainly those released from HS cell cultures. The proportion of both IL-17+IFN-γ+ (CD4+ and CD8+) T cells and IL-17+IFN-γ−CD8+ T cells was positively related with neurological disorders, determined by EDSS score. The addition of 1,25(OH)2D reduced not only these pathogenic T cell subsets but elevated the percentage of IL-10-secreting conventional (FoxP3+CD25+CD127−CD4+) and non-conventional (IL-17+) regulatory-like T cells. Taken together, the results indicate that the active form of vitamin D should benefit MS patients by attenuating the percentage of pathogenic T cells. This effect could be direct and/or indirect, by enhancing classical and non-classical regulatory T cells.