I doubt whether anyone knows exactly how much sun
one needs to avoid MS or even if that would be
sufficient to completely protect one from the disease. I
would suggest, though, that it might be a good idea to
get at least an hour or two of direct sunlight early
in the morning or late in the afternoon (when the
sun is low on the horizon and the harmful rays are
filtered out by the atmosphere). If that is not feasible,
supplementation with vitamin D is definitely in order.