In a multi-year study done on 465 patients with multiple sclerosis, patients whose vitamin D levels rose 50 nm/L (nanomoles per liter) over the course of the first year experienced a 57% lower risk of developing new lesions. They also had 57% less probability of a relapse.
Some experts believe that vitamin D supplementation is risky, and more studies should be done before a recommendation should be given. But the results of at least this study are promising. Considering that vitamin D deficiency is so widespread, and that vitamin D is vital to so many functions in the body, ensuring that levels are at least within normal limits through supplementation is prudent.
Article: Vitamin D May Slow Multiple Sclerosis, Study Suggests