High levels of Vitamin D, 10,000 a day, could help ramp down the immune system which could help deflate the progression of MS. When i moved to Oregon and experienced the dismal, dark days of winter, my Vitamin D levels got dangerously low. There is some research that low levels of Vitaman D can be part of what causes MS. That and the fact i was exposed to a virus or toxin by the age of 15, which was Mono. These two combination could be part of why i got MS.
Reaserch is coming closer in understanding under what circumstance MS develops.