Vitamin D crucial for fighting infection, TB

Kathleen Blanchard's picture
Vitamin D activates crucial proteins to fight tuberculosis
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Vitamin D is known to boost the immune system, but now researchers say the so called sunshine vitamin is also essential for fighting tuberculosis, a disease that causes 1.8 million deaths annually. Scientists have discovered the immune system doesn't work when vitamin D levels are inadequate.

Researchers have noted dark skinned people in Africa are more susceptible to tuberculosis. They also know dark skin blocks absorption of the UV rays, reducing vitamin D production.

Results of a study published October 12, 2011 in the journal Science Translational Medicine found infection fighting T-cells that activate a protein called interferon become inactive without enough vitamin D.

What that means is the body can’t launch an immune response without enough vitamin D.

For their study, the researchers tested blood serum samples from health individual with and without adequate levels of vitamin D and compared them.

They found low vitamin D levels, as found in Africans, failed to trigger an immune response. When they added vitamin D, which is actually a hormone, the immune defense was activated.

Tuberculosis colonies treated with interferon was 85 percent eliminated when adequate levels of vitamin D were present.

Dr. Mario Fabri, who conducted the research at UCLA and is currently at the Department of Dermatology at the University of Cologne, Germany says, “Our findings suggest that increasing vitamin D levels through supplementation may improve the immune response to infections such as tuberculosis.”

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Tuberculosis has been treated with vitamin D over the centuries. Some people may remember sanatoriums where patients with the disease were isolated and placed in the sunshine as a part of their treatment plan.

Previous studies have shown that vitamin D also promotes the production of a molecule called cathelicidin that helps kill the TB bacteria.
Senior investigator Dr. Robert Modlin said, "The findings of our previous research with innate immunity provided us with a new opportunity to take a look at the effects and role of Vitamin D with acquired immunity, both critical systems of human defense."

In the study, the scientists found innate and acquired immunity both follow the same pathways to kill tuberculosis, though they use different receptors.

“These current findings provide the first credible mechanistic explanation for how vitamin D critically contributes to acquired T-cell immunity that protects us from infections, particularly tuberculosis,” said Modlin.

The study is also the first to show the protein interferon-γ activates immune cells to fight TB. Until now researchers didn’t know vitamin D was necessary to help interferon-y.

Study author Dr. John Adams, professor of orthopedic surgery, Geffen School of Medicine. “Now we understand better how this chain reaction works.”

“At a time when drug-resistant forms of tuberculosis are emerging, understanding how to enhance natural innate and acquired immunity through vitamin D may be very helpful,” said co-author Barry Bloom, former dean of the faculty at the Harvard School of Public Health.

The researchers say clinical trials are needed to find out if vitamin D supplements increase resistance to tuberculosis and other infections. The new study shows vitamin D is essential for fighting tuberculosis through a chain reaction that boosts immune defenses.

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Image credit: morguefile

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