Exposure to UV rays boost vitamin D, may protect against auto-immune disease — ScienceDaily

Living in sunny locations and spending time outdoors may increase your risk of skin cancer, but a new study led by UC San Francisco and the Australian National University shows sun exposure in children and young adults may protect against multiple sclerosis. The study follows previous work by other researchers who have shown a link between increased exposure to ultraviolet radiation in childhood and a lower risk of developing MS in adulthood.

The study included 332 participants, ages 3 to 22, who had MS for an average of seven months. Their locations and amount of sun exposure were compared by age and sex with 534 participants without MS, the researchers reported in their study, to be published Dec. 8, 2021 in the online issue of Neurology, the journal of the American Academy of Neurology. .

In questionnaires completed by participants with MS or their parents, 19 percent said they spent less than 30 minutes a day outside during the past summer, compared with 6 percent of those who did not have MS. When the researchers adjusted for MS risks, such as smoking and female gender, they found that participants who spent an average of 30 minutes to an hour outside the home each day had a 52 percent lower chance of developing MS, compared with those who spent an average of less than 30 minutes outside each day. .

“Sun exposure is known to increase vitamin D levels,” says co-senior author Emmanuelle Waubant, MD, PhD, a professor in the UCSF Department of Neurology and of the Weill Institute for Neurosciences. “It also stimulates immune cells in the skin that play a protective role in diseases such as MS. Vitamin D may also alter the biological function of the immune cells and as such play a role in protecting against autoimmune diseases.”

Progression slower in pediatric MS, despite inflammatory onset

While MS usually affects adults between the ages of 20 and 50, about 3 to 5 percent of the approximately one million patients in the United States with the condition begin to have symptoms in childhood. MS in children is highly inflammatory at first, but takes longer than adults to progress, with symptoms of secondary progression, such as moderate to severe weakness, poor coordination, and bowel and bladder control, which experts say start an average of 28 years after the start of the disease. the disease occur. . However, these disability landmarks are reached about 10 years earlier than in adult MS.

The researchers also found a link with sunlight intensity and estimated that Florida residents were 21 percent less likely to have MS than New York residents. They 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, they said.

Fortunately, using sunscreen does not appear to diminish the therapeutic effects of sunlight in warding off MS, noted Waubant, who is also director of the UCSF Regional Pediatric Multiple Sclerosis Center. Clinical trials are needed to determine whether “increased sun exposure or vitamin D supplementation can prevent the development of MS or alter the course of the disease after diagnosis,” she said. Meanwhile, “advising regular time in the sun of at least 30 minutes a day, especially in summer, and using sun protection when necessary, especially for first-degree relatives of MS patients, can be a valuable intervention to reduce the incidence of MS.” Reduce.”

Limited sun exposure and/or low vitamin D levels have been linked to other conditions. These include Parkinson’s disease, Alzheimer’s disease and other dementias, as well as schizophrenia and other autoimmune diseases such as type 1 diabetes, Crohn’s disease and lupus.

Senior co-author is Robyn Lucas, MBChB, PhD, of the Australian National University in Canberra. Lead author is Prince Sebastian, PhD, also from the Australian National University. Please refer to the study for a full list of co-authors and potential conflicts of interest.

The study was funded by the National Institutes of Health (RO1NS071463, EW) and the National MS Society (HC0165, CC)

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