How can increasing vitamin D help?
Increasing vitamin D has been tied to a lower risk for MS and may explain the sunshine effect that researchers found. Waubant suspects that a combination of sunshine increasing vitamin D and revving up immune cells in the skin is protective.
“We think it could be not only vitamin D, but also the fact that there are immune cells in the skin, and these immune cells are stimulated by exposure to the sun, and that is unrelated to vitamin D,” she says. “Those immune cells are actually good immune cells — they help dampen inflammation.”
For the study, Waubant’s team studied more than 300 children and young adults with MS and more than 500 without the disease. Participants ranged from ages 3 to 22. Their parents answered questions about how much time their child spent in the sun in the summer before the study.
In all, 19% of those with MS had spent fewer than 30 minutes a day outdoors, compared with 6% of those without MS. Also, 18% of those with MS spent one to two hours a day outdoors, compared with 25% of those without MS.
Waubant’s team calculated that those who spent 30 to 60 minutes a day outdoors had a 52% lower risk of developing MS, compared with those who spent less than a half-hour a day outdoors.
More time in the sun reduced the risk even more.
Compared with participants who were outdoors less than a half-hour a day, those who spent one to two hours a day had an 81% lower risk of MS, researchers found. More hours outdoors than that didn’t reduce the risk further, Waubant notes.
Sun exposure in the first year of life also lowered MS odds.