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Maybe it’s not the vitamin D from the sun that helps people with multiple sclerosis, but rather the UVB radiation.

That’s right… the same radiation that causes skin cancer.

A study out of Harvard under the team of Helen Tremlett, PhD, a professor in neuroepidemiology and multiple sclerosis at the Djavad Mowafaghian Centre for Brain Health, mapped the sun exposure over the life of multiple sclerosis patients using state-of-the-art information from NASA.

Taken from the Nurses’ Health Study cohort, 3,226 people with multiple sclerosis (MS) were geocoded.

This information was then cross referenced and analyzed with data from NASA tracking UVB radiation.

Tremlett and her team went to Boston specifically for the Nurses’ Health Study cohort.

“It is a huge and powerful resource to look at these kinds of questions. They have been following women who were nurses across the U.S. Over time, some have developed conditions such as MS,” Tremlett told Healthline.

Those who lived in high UVB areas had a 45 percent lower risk of MS. Also associated with a reduced risk was high summer sun exposure in high UVB areas.

“People didn’t have to have a lot of skin showing, but just to be outside in the sunlight,” Tremlett said.

The body creates vitamin D when exposed to sunlight. However, the study suggests that there is more than vitamin D at play here.

“We don’t know how it works,” said Tremlett, “It could be, for example, that the sun hits the retina in the back of the eye, which influences how much melatonin you produce, which affects circadian rhythm. This could affect wake and sleep cycle and immune regulation,” Tremlett suggested.

Another sunny study

Another research project, the Sunshine Study, looked at lifetime sun exposure and its relationship to MS.

In addition, this study analyzed vitamin D levels and divided the cases and controls among Caucasians and people of African and Hispanic descent.

The cases and controls were taken from the membership out of Kaiser Permanente Southern California.

Many studies have documented the relationship between vitamin D and MS. But this study questions vitamin D as a cause for MS and its role in achieving better health, especially for people of African and Hispanic descent.

Higher vitamin D was associated with a lower risk of MS only in Caucasians, not in people of African and Hispanic descent. There was no association for the other subgroups.

It also found that lifetime exposure appears to reduce the risk of MS regardless of race or ethnicity.

“People who spend more time outdoors are usually engaging in some form of exercise like walking, hiking, biking, jogging, or gardening. So, it may be the combination of exercising outdoors that is really protecting people from developing MS,” said Dr. Annette Langer-Gould, who is associated with Kaiser Permanente Southern California in Pasadena, a member of the American Academy of Neurology, and a study author.

Vitamin D levels are an easy way to measure this indirectly in Caucasians, but not in people of Hispanic or African descent, whose vitamin D levels don’t go up as much, even with the same amount of sunlight exposure.

“My recommendation is get your sunlight from natural sources, wear sunscreen to prevent skin cancer, and try to spend an average of 30 minutes a day engaging in outdoor activities like walking or gardening,” Langer-Gould told Healthline.

“It has something to do with the immune system, ultra violet increasing regulatory cells,” explained Nick LaRocca, PhD, vice president of healthcare delivery and policy research for the National Multiple Sclerosis Society.

“Interest has been growing that UV radiation plays a roll in the risk of MS, independent of the role of vitamin D,” he told Healthline.

These studies focused on where people grew up and the connection to MS.

A study begins in Australia

Last year, Prue Hart, PhD, of Western Australia, successfully used UV radiation on MS patients that had one attack but no further disease activity.

With positive results, Hart then created the PhoCIS Trial to further study the effects of UV radiation (phototherapy) on MS patients with Clinically Isolated Syndrome (CIS).

This study is currently recruiting.

“If the role of sunlight is more complex than originally thought, then we need to find it out,” LaRocca said, adding “in reference to everything with MS, it’s complicated.”

Editor’s note: Caroline Craven is a patient expert living with MS. Her award-winning blog is GirlwithMS.com, and she can be found on Twitter.