The exposure to Ultraviolet rays increases vitamin D levels, which may protect against auto-immune disease, according to a  study. The study's findings were published in the online issue of 'Neurology,' the American Academy of Neurology's magazine.

The study builds on prior studies that found a link between increased ultraviolet exposure in childhood and a lower risk of adult multiple sclerosis (MS).

The study included 332 people aged 3 to 22 who had been diagnosed with MS for an average of seven months. According to the researchers, their locations and amount of sun exposure were matched by age and sex to 534 participants without multiple sclerosis.

In questionnaires filled out by MS patients or their parents, 19 percent said they spent fewer than 30 minutes per day outside during the previous summer, compared to 6 percent of those who did not have MS. When the researchers took into account MS hazards such as smoking and female sex, they discovered that people who spent 30 minutes to one hour outside daily had a 52 percent lower risk of MS than those who spent less than 30 minutes outside daily.

Emmanuelle Waubant, MD, PhD, co-senior author and professor at the UCSF Department of Neurology and the Weill Institute for Neurosciences, said, "Sun exposure is known to raise vitamin D levels."

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