Hello, my fellow MSer! Since you are also not part of the "normal" population, this should be of interest to you to at least investigate. If you insert the two phrases "Multiple Sclerosis" "Vitamin D3" together into your search engine, you'll see a lot of interesting (and relatively recent) info. In short, besides the theory that insufficient D3 puts people at greater risk for developing MS, it is also believed to possibly be beneficial for those who already have it. For those in whom there is a clinical reason to supplement with D3, it's just really not possible to get enough from the sun without bad side effects.