Ultraviolet radiation, vitamin D and multiple sclerosis.

There is compelling epidemiological evidence that the risk of developing multiple sclerosis is increased in association with low levels of sun exposure, possibly because this is associated with low vitamin D status. Recent work highlights both vitamin D and non-vitamin D effects on cellular immunity that suggests that higher levels of sun exposure and/or vitamin D status are beneficial for both MS risk and in ameliorating disease progression. Here we review this recent evidence, focusing on regulatory cells, dendritic cells, and chemokines and cytokines released from the skin following exposure to ultraviolet radiation.