Sunlight Per Se, Not Vitamin D, Energizes Human Immunity
In fact, we may have been giving vitamin D a bit more credit than it deserves. “Some of the roles attributed to vitamin D on immunity may be due to this new mechanism,” said Gerard Ahern, one of the study’s authors and an associate professor at the Department of Pharmacology and Physiology in Georgetown University Medical Center.
They found that T cells exposed to sun rays actually begin to move faster. (T cells are a kind of white blood cells. They are actively involved in finding and destroying germ-infected or cancerous cells, among other things.) This accelerated movement helps them to do their job more effectively.
In a way, this T-cell boosting mechanism even has one over the vitamin D-producing mechanism. That’s because to boost T cells, only blue light from the sun is required. On the other hand, vitamin D production requires ultraviolet rays. This carries with it a risk of skin cancer.
The investigators also found a clue on how sunlight activates T cell movement. Apparently, the light synthesizes hydrogen peroxide within the T cells. “We know that an immune response also uses hydrogen peroxide to make T cells move to the damage,” Ahern said, adding that these two pieces of data fit in with each other.
Details of this study appeared in December 2016 in the journal Scientific Reports.