How Immune Health Depends on Vitamin D

Quoting Kate Kelland:

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.

"When a T cell is exposed to a foreign pathogen, it extends a signaling device or ’antenna’ known as a vitamin D receptor, with which it searches for vitamin D ... This means the T cell must have vitamin D or activation of the cell will cease.  If the T cells cannot find enough vitamin D in the blood, they won’t even begin to mobilize."

So unless you spend about 20 minutes a day outside in the noontime sun -- or take a vitamin D supplement -- your immune system can’t do its job effectively.