sábado, 27 de marzo de 2010

El Sol Es Nuestra Primera Defensa


Body's First Line of Defense Depends on Sunshine Vitamin

Updated: 15 days 4 hours ago
Katie Drummond
Katie Drummond Contributor
(March 8) -- Your body's first line of defense can benefit from an ample dose of the sunshine vitamin, according to a new study that examined the link between vitamin D and human immunity.

Estimates suggest that about half the world's population suffer from inadequate levels of the vitamin, which is produced by the body through sun exposure and found in dietary sources such as fish, cod-liver oil and fortified milk.

A shortage of vitamin D has already been linked to dozens of health problems. The vitamin is essential for the creation of strong bones, healthy blood pressure and maybe even the reduction of unhealthy body-fat accumulations. Low levels might also increase the risk of developing cancer and multiple sclerosis.

Findings from the University of Copenhagen, published this week in Nature Immunology, now suggest that vitamin D might also activate the body's T cells -- the immune system's first response to invading viruses and bacteria.

"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," Carsten Geisler, the study's lead author, told Reuters.

If an individual is suffering from a shortage of the vitamin, T cells won't activate to respond to the threat. The researchers think their findings could have implications for everything from the common cold to combating global epidemics.

But, in most parts of the world, we're spending more and more time indoors. As a consequence, vitamin D levels continue to drop. A recent study out of California found that 59 percent of subjects -- healthy, young women living in Southern California -- were suffering from insufficient levels of vitamin D.

That study also concluded that insufficient vitamin D could cause increased levels of unhealthy body fat. The research suggests that those body-fat levels could heighten a person's risk of developing a spectrum of illnesses that the body's immune system couldn't fend off.

"It's certainly the most common nutritional deficiency and likely the most common medical problem in the world," Dr. Michael Holick, a professor of medicine at Boston University, told BU Today.

The new insight might encourage use of vitamin D to improve lifesaving procedures, like organ transplants. T cells usually mobilize to fight back -- and reject -- new organs. Controlling the circulation of vitamin D could prevent the adverse reactions.

Those under age 50 should be getting 200 international units of vitamin D each day, with the recommended dose rising for the elderly. But debate persists over whether those doses are high enough. The Institute of Medicine is reviewing the latest research and plans to publish revised recommendations in May.

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