The so-called sunshine vitamin, which can be obtained from food or manufactured by human skin exposed to the sun, plays a key role in boosting the immune system, researchers believe.
In particular it triggers and arms the body's T cells, the cells in the body that seek out and destroy any invading bacteria and viruses.
Scientists at the University of Copenhagen have discovered that Vitamin D is crucial to activating our immune defences and that without sufficient intake of the vitamin, the killer cells of the immune system – T cells – will not be able to react to and fight off serious infections in the body.
For T cells to detect and kill foreign pathogens such as clumps of bacteria or viruses, the cells must first be ‘triggered’ into action and "transform" from inactive and harmless immune cells into killer cells that are primed to seek out and destroy all traces of invaders.
The researchers found that the T cells rely on vitamin D in order activate and they would remain dormant, ‘naïve’ to the possibility of threat if vitamin D is lacking in the blood.
Professor Carsten Geisler from the Department of International Health, Immunology and Microbiology, said: "When a T cell is exposed to a foreign pathogen, it extends a signalling device or ‘antenna’ known as a vitamin D receptor, with which it searches for vitamin D.
"This means that 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 mobilise. ”
The discovery, the scientists believe, provides much needed information about the immune system and will help them regulate the immune response.
This is important not only in fighting disease but also in dealing with anti-immune reactions of the body and the rejection of transplanted organs.
Vitamin D 'triggers and arms' the immune system - Telegraph