Being in the sun can keep infections at bay

Vitamin D is vital in activating human defenses and low levels suffered by around half the world's population may mean their immune systems' killer T cells are poor at fighting infection, scientists say.

The findings by Danish researchers could help the fight against infectious diseases and global epidemics, they say, and could be particularly useful in the search for new vaccines.

The researchers found that immune systems' killer cells, known as T cells, rely on vitamin D to become active and remain dormant and unaware of the possibility of threat from an infection or pathogen if vitamin D is lacking in the blood.