Sunshine effects on MS might be more complicated than previously thought, mouse study suggests
Ultraviolet radiation from sunshine seems to thwart multiple sclerosis, but perhaps not the way most researchers had assumed, a new study in mice suggests.
If validated in further research, the finding could add a twist to a hypothesis that has gained credence in recent decades. The report appears online March 22 in the Proceedings of the National Academy of Sciences.
Scientists have hypothesized that MS is rare in the tropics because people synthesize ample vitamin D from exposure to the UV radiation in equatorial sunlight. What’s more, MS is more common in the high latitudes of northern parts of Europe and North America than in regions farther south. That pattern has led to the assumption that higher levels of vitamin D might prevent people from developing MS, what became known as the latitude hypothesis.
But a direct cause-and-effect relationship between vitamin D deficiency and MS has never been established. In past experiments, giving vit