According to a new study, exposure to ultraviolet (UV) rays increases vitamin D levels, which may protect against auto-immune disease.
The findings of the study were published in the online issue of ‘Neurology’, the journal of the American Academy of Neurology.
The study follows 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. Their locations and amount of sun exposure were matched by age and sex to 534 participants without MS, the researchers reported in their study.
In questionnaires filled in by participants with MS or their parents, 19 percent stated that they spent less than 30 minutes daily outdoors during the previous summer, compared to 6 percent of those who did not have MS.
When the researchers took into account MS risks 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.
“Sun exposure is known to boost vitamin D levels,” said co-senior author Dr. Emmanuelle Waubant, MD, PhD, professor in the UCSF Department of Neurology and of the Weill Institute for Neurosciences.
“It also stimulates immune cells in the skin that have a protective role in diseases such as MS. Vitamin D may also change the biological function of the immune cells and, as such, play a role in protecting against autoimmune diseases,” added Dr. Waubant.
“Pediatric-onset MS is initially highly inflammatory, but takes longer than adults to advance, with symptoms of secondary progression, such as moderate to severe weakness, poor coordination and bowel, and bladder control, occurring on average 28 years after disease onset,” according to health experts. However, these disability landmarks are reached approximately 10 years earlier than in adult MS.
The researchers noted that sun exposure was “dose-dependent,” the longer the exposure the lower the risk. “And even exposure in the first year of life seemed to protect against MS,” the study said.
“Fortunately, the use of sunscreen does not appear to lessen the therapeutic effects of sunlight in warding off MS. Clinical trials are needed to determine if increasing sun exposure or vitamin D supplementation can prevent the development of MS or alter disease course post-diagnosis,” Dr. Waubant noted.
