Scientists find why sunshine vitamin D is crucial

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Scientists find why " sunshine " vitamin D is crucial

_http://www.discoveryon.info/2010/03/vitamin-d.html_

(http://www.discoveryon.info/2010/03/vitamin-d.html)

 

 

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 said on Sunday.

 

 

The findings by Danish researchers could help the fight against infectious

diseases and global epidemics, they said, 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.

 

 

" 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, " said Carsten Geisler of Copenhagen University's department of

international health, immunology and microbiology, who led the study.

 

 

" 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. "

 

 

Scientists have known for a long time that vitamin D is important for

calcium absorption, and that there is a link between levels of the vitamin and

diseases such as cancer and multiple sclerosis.

 

 

" What we didn't realize is how crucial vitamin D is for actually

activating the immune system -- which we know now, " Geisler wrote in the study

in

the journal Nature Immunology.

 

 

Most Vitamin D is made by the body as a natural by-product of the skin's

exposure to sunlight. It can also be found in fish liver oil, eggs and fatty

fish such as salmon, herring and mackerel, or taken as a supplement.

 

 

Almost half of the world's population has lower than optimal levels of

vitamin D and scientists say the problem is getting worse as people spend more

time indoors.

 

 

Geisler and his research team said the findings offered much needed

information about the immune system and would be of particular use when

developing new vaccines.

 

 

" 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, "

they wrote.

 

 

Active T cells multiply at an explosive rate and as well as fighting

infection, can also mistakenly attack the body itself.

 

 

After and an organ transplant, for example, T cells can attack the new

organ as a " foreign invader, " and in autoimmune disease, hypersensitive T

cells mistake parts of the body's own cells as threats, prompting the body to

attack itself.

 

 

Geisler said there were no definitive studies on the optimal daily vitamin

D dose but experts recommend 25 to 50 micrograms.