There is now a very comprehensive literature relating lack of sun exposure to the risk of developing MS.
Further there is a growing evidence base behind the potential for vitamin D supplementation both to prevent MS and to reduce relapse rate in people diagnosed with MS.
Researchers from Fiona Stanley's Institute for Child Health Research in Western Australia have now summarised the literature showing that sun exposure has profound effects on modulating the immune response independent of vitamin D.
We know that vitamin D is a marker of how much sun exposure one has, and so it has been tempting to think that just correcting that low level through supplementation will correct the immune problems caused by lack of sun exposure.
However, while it does appear that vitamin D supplementation is helpful for PwMS, it seems likely that sun exposure is required as well for the optimal immune benefit. Of course, in some parts of the world, sun exposure for much of the year is difficult, and so vitamin D supplements have to suffice.
But for those who can, obtaining the OMS-recommended 10-15 minutes of sun as close to all over as possible 3-5 times a week (longer if the UV index is less than 7), in addition to vitamin D supplementation, would appear to hold the most promise for optimal immune function and reduction of risk of progression of the illness.