Just as a postscript to this: The June/July 2016 issue of
Neurology Now contains two letters about people with MS who believe that increasing their vitamin D3 by supplementation has helped their MS, and there is an editorial comment in reply to the letters:
Thank you for sharing your experiences with vitamin D. Despite such anecdotal evidence, experts would advise caution in interpreting the effect of the vitamin on MS or other conditions, which is why they stress the need for better and larger studies.