Sunlight May Protect Against Multiple Sclerosis

Children and young adults who are exposed to sun may be protected against getting multiple sclerosis (MS), results of a study by UC San Francisco (UCSF) and Australian National University showed.

The study follows previous work that demonstrated an association between increased ultraviolet exposure in childhood and lower odds of adult MS.

The results were published in Neurology, the journal of the American Academy of Neurology.

"Sun exposure is known to boost vitamin D levels," Emmanuelle Waubant, MD, PhD, professor in the department of neurology at UCSF, said in a statement.

"It also stimulates immune cells in the skin that have a protective role in diseases such as MS,” she said. “Vitamin D may also change the biological function of the immune cells and, as such, play a role in protecting against autoimmune diseases."

The study included 332 individuals between aged 3 and 22 years, who had MS for an average of 7 months. They were matched with individuals without MS by age, gender, location, and sun exposure.

Investigators found that in questionnaires filled out by individuals with or without MS or their parents, 19% said that they spent less than 30 minutes daily outdoors during the previous summer compared with 6% of those who did not have MS.

Investigators adjusted for MS risk, such as being female or smoking, and found that individuals who spent an average of 30 minutes to 1 hour outdoors daily had a 52% lower chance of MS compared with those who spent less than 30 minutes outdoors daily.

Although MS is prevalent in adults between the aged 20 and 50 years, about 3% to 5% of the approximately 1 million individuals in the United States began experiencing symptoms during childhood.

Pediatric onset of MS is initially high inflammation, but it takes longer than adults to advance, with symptoms of secondary progression, such as moderate to severe weakness, poor coordination, and bowel and bladder control, which occurs, on average, 28 years after disease onset, according to the statement.

Investigators also found an association with the intensity of sunlight and a decreased risk of MS. They estimated that residents of Florida would be 21% less likely than residents of New York to have MS.

They said that sun exposure is “dose dependent,” so the longer an individual is exposed to sunlight, the less likely they are to have MS.

They added that even exposure in the first year of life seemed to protect against MS.

They also added that the use of sunscreen does not appear to lessen the therapeutic effects of sunlight, Waubant said.

Clinical trials are needed to determine if sun exposure or vitamin D supplements can prevent the development of MS.

"Advising regular time in the sun of at least 30 minutes daily especially during summer, using sun protection as needed, especially for first degree relatives of MS patients, may be a worthwhile intervention to reduce the incidence of MS,” Waubant said

Limited sun exposure and/or low levels of vitamin D have been associated with other conditions, such as Alzheimer, Crohn, and Parkinson diseases; lupus, other types of dementia, and type 1 diabetes.

Reference

Sunshine may shield children, young adults from MS. ScienceDaily. News release. December 8, 2021. Accessed December 14, 2021. https://www.sciencedaily.com/releases/2021/12/211208161146.htm