Not just important for building strong bones, an international team of scientists has found that vitamin D also plays an essential role in the body’s fight against infections such as tuberculosis.
A potentially fatal lung disease, tuberculosis is estimated to cause 1.8 million deaths annually and especially impacts those with reduced immunity such as HIV-infected individuals, according to the World Health Organization.
In an interesting twist, people with darker skin traditionally have had a higher susceptibility to tuberculosis and areas of Africa lead the world with the highest infection rates. Scientists believe this may be partly due to the skin pigment melanin, which is more abundant in darker skin that shields the body from absorbing ultraviolet rays, but also reduces vitamin D production.
Vitamin D — a natural hormone, rather than a vitamin– is known to be instrumental in bone development, but also may protect against cancer and autoimmune diseases, as well as fight infections.
Published online Oct. 12 in the peer-reviewed journal, Science Translational Medicine, researchers examined the mechanisms that govern the immune system’s ability to kill or inhibit the growth of pathogens such as M. tuberculosis, the bacteria causing tuberculosis.
The team found that T-cells, which are white blood cells that play a central role in immunity, release a protein called interferon- that triggers communication between cells and directs the infected immune cells to attack the invading tuberculosis bacteria. However, this activation requires sufficient levels of vitamin D to be effective.
Researchers next tested serum taken from blood samples in healthy humans with and without sufficient vitamin D and found that the immune response was not triggered in serum with lower vitamin D levels, such as those found in African Americans. But, when adequate vitamin D was added to deficient serum, the immune response was effectively activated.
Scientists found that there was an 85 percent reduction of colony-forming tuberculosis bacteria in human macrophage cells that were effectively treated with interferon- in the presence of sufficient vitamin D.
“Over the centuries, vitamin D has intrinsically been used to treat tuberculosis. Sanatoriums dedicated to tuberculosis patients were traditionally placed in sunny locations that seemed to help patients — but no one knew why this worked,” said first study author Dr. Mario Fabri, who conducted the research at UCLA and is currently at the Department of Dermatology at the University of Cologne, Germany. “Our findings suggest that increasing vitamin D levels through supplementation may improve the immune response to infections such as tuberculosis.”