Genetic susceptibility cannot fully explain the geographical variations in Multiple Sclerosis. There are a number of other factors which are consistent predictors of MS risk, including cigarette smoking, infection with the Epstein-Barr virus ... and vitamin D status.
A number have studies have shown that latitude correlates very closely with MS risk, and the most important factor that changes with latitude is the duration and intensity of sunlight. There is evidence of both reduced sun exposure and reduced vitamin D status for MS patients. Overall, the results of epidemiological studies support a protective role for vitamin D.
For MS prevention, adequate vitamin D status during childhood and adolescence is particularly important.
* Seminars in Neurology 2008; 28: 017-028