Another reason vitamin D is important: It gets T cells going

Vitamin D deficiency has been linked to a rapidly expanding inventory of ailments—including heart disease, cancer and the common cold. A new discovery demonstrates how the vitamin plays a major role in keeping the body healthy in the first place, by allowing the immune system's T cells to start doing their jobs.

In order for T cells to become active members of the body's immune system, they must transition from so-called "naive" T cells into either killer cells or helper cells (which are charged with "remembering" specific invaders). And, if ample vitamin D is not around, the T cells do not make that crucial transition, a group of researchers led by Carsten Geisler, head of the Department of International Health, Immunology and Microbiology at the University of Copenhagen, found. They draw this conclusion based on their experiments with isolated naïve human T cells.