Researchers have long known that the incidence of multiple sclerosis seems to be more common in higher latitudes than those in the tropics. One reason they surmised is that it may be because of the amount of sunlight that the tropics receive and the less of it that those in the higher latitudes are able to get. The researchers from the University of Wisconsin-Madison are trying to find out whether it is the Vitamin D from the sunlight or the ultraviolet light that may have the significant effect on MS.
Although vitamin D in the sunlight may help reduce the symptoms of MS, a recent study headed by Hector DeLuca, Steenbock Research Professor of Biochemistry at University of Wisconsin-Madison, and first author Bryan Becklund suggests that it is the UV light coming from the sun that might play a bigger role in controlling MS. The UV portion of sunlight helps stimulate the body to produce vitamin D. Both may then work together to regulate the immune system that might slow down the effects of MS. But scientists have yet to know whether it is the UV light, vitamin D, or even both that may actually regulate the immune system.
In order to study the said effects, the researchers used a mice model susceptible to an MS-like disease. They triggered the disease by infecting a certain protein from the nerve fibers. The mice are then exposed to moderate UV radiation levels for a week. After injecting the protein that triggered the MS-like disease in mice, irradiation was done every second or third day. The UV exposure was equivalent to two hours of direct sun exposure during the summer.
The results of the study showed that the UV exposure did not have an effect on how many mice developed the disease. But it did reduce the symptoms of MS which were especially displayed on those mice that were exposed to UV light every other day. Although the UV exposure did help increase the vitamin D levels , the said effect did not provide a clear explanation on the reduction of MS symptoms.
According to DeLuca, "We are looking to identify what compounds are produced in the skin that might play a role, but we honestly don’t know what is going on. Somehow it makes the animal either tolerate what’s going on, or have some reactive mechanism that blocks the autoimmune damage."
"There are several ways this could go. If we can find out what the UV is producing, maybe we could give that as a medicine. In the short term, if we can define a specific wavelength of light that is active, and it does not overlap with the wavelengths that cause cancer, we could expose patients who have been diagnosed with MS to that wavelength," DeLuca further added.
Source: University of Wisconsin-Madison. "Exploring the Link Between Sunlight and Multiple Sclerosis." ScienceDaily 23 March 2010. 30 March 2010