MINNEAPOLIS, Minn. — A half-hour walk each day can halve a child or young adult’s risk of developing multiple sclerosis, according to a new study. Researchers with the American Academy of Neurology say young people who spend most time outdoors — taking in ultraviolet light from the Sun — are less prone to the condition.
The findings add to evidence that vitamin D, produced by sunlight, has a protective effect on the human body. The devastating neurological condition is more common in cloudier countries further away from the equator.
“Providing guidance on the best amounts of sunlight exposure to get while weighing the benefits against the risks is challenging,” says lead author Dr. Emmanuelle Waubant from the University of California-San Francisco in a media release.
“We found that spending between one and two hours outdoors daily provided the most benefit, but spending as little as 30 minutes outside daily may cut risk of MS roughly in half.”
Since agencies like the CDC don’t consider sunlight a “consistent source” of vitamin D, due to issues like the weather and air pollution, health officials encourage people to also consume the nutrient through food and supplements.
More time outdoors dramatically cuts MS risk
The study, published in the journal Neurology, examined 332 children, teens, and young adults with MS for an average of seven months. Researchers matched their test results with 534 healthy peers of similar age and sex. Participants ranged in age from three to 22 years-old.
Those who spent an average of 30 minutes to an hour outside each day during the previous summer had a 52-percent lower chance of developing MS. Those who averaged between one and two hours a day outside had an 81-percent reduced risk — compared to peers with less than half an hour of exposure to vitamin D.
The team also took into account factors such as smoking exposure and gender, finding that MS is more common among women and smokers.
“It’s important to note that too much sun exposure without protection also has risks, and our study found that spending two hours or more outside daily did not further reduce the risk of MS compared to one to two hours,” Dr. Waubant says.
The study also found those living in sunnier areas of the United States and those who had more sun exposure in their first year of life also had lower odds of developing multiple sclerosis. For example, someone living in Florida was 21 percent less likely to have MS compared to someone living in New York.
What exactly is MS?
While rare, MS can develop in children. Most patients, however, begin developing symptoms between the ages of 20 and 50. Study authors measured sun exposure as time spent outdoors and use of sun protection like a hat, clothing, and sunscreen. They calculated the amount of ultraviolet light received based on where participants lived at birth and at the time of the study.
The children or their parents and guardians answered a questionnaire about how much time they spent outdoors daily at various ages and over the past year. In the summer before the study, 19 percent of the MS patients spent less than 30 minutes outdoors, compared to six percent of those who did not have MS.
Another 18 percent of the patients spent one to two hours outdoors, compared to 25 percent of those without the condition. Dr. Waubant and colleagues note their study does not prove sun exposure prevents MS but does show an association.
Multiple sclerosis is an unpredictable, disabling autoimmune disease of the central nervous system. The disease eats away at the protective covering of the nerves, leading to continuous pain and fatigue.
Symptoms range from numbness and tingling to blindness and paralysis in more severe cases. There is currently no cure for MS and the disease affects women three times more often than men.
How much vitamin D should children get?
Vitamin D is also found in small amounts in oily fish, eggs, meat, milk, and margarine. Some cereals and yogurts are also fortified with the nutrient. The CDC recommends that children between 12 and 24 months receive 600 IU (international units) of vitamin D each day.
“We know MS is more common in countries further away from the equator,” says the Multiple Sclerosis Society in a statement to SWNS. “There are many possible reasons for this pattern. But researchers are particularly interested in the role that sunlight (and therefore vitamin D) could play in MS.”
“In 2015 scientists demonstrated a clear link between low vitamin D and MS,” the society tells SWNS. “They found people who naturally had lower levels of vitamin D (because of their genetics) were more likely to develop MS. Researchers in Oxford have also discovered vitamin D could affect the way a gene linked to MS behaves. They showed when vitamin D was present, the gene was more active. This groundbreaking research could help us understand more about the role vitamin D plays in developing MS.”
South West News Service writer Mark Waghorn contributed to this report.