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|Tea and health|
Penny Kris-Etherton, a nutrition specialist at Penn State University, said Bukowski's study adds to growing eviden-ces that tea is an effective disease fighter.
"This is potentially a very significant finding," she said. "We're seeing multiple benefits from tea."
But she said the work needs to be confirmed in a much larger study, involving more people.
In the study, Bukowski and his co-authors isolated from ordinary black tea a substance called L-theanine.
Bukowski said L-theanine is broken down in the liver to ethylamine, a molecule that primes the response of an immune system element called the gamma-delta T cell.
"We know from other studies that these gamma-delta T cells in the blood are the first line of defense against many types of bacteria, viral, fungal and parasitic infections," he said. "They even have some anti-tumor activity."
The T cells prompt the secretion of interferon, a key part of the body's chemical defense against infection, Bukowski said.
"We know from mouse studies that if you boost this part of the immune system it can protect against infection," he said.
To further test the finding, the researchers had 11 volunteers drink five cups of tea a day, and 10 others drink coffee. Before the test began, they drew blood samples from all 21 test subjects.
After four weeks, they took more blood from the tea drinkers and then exposed that blood to the bacteria called E-coli. Bukowski said the immune cells in the specimens secreted five times more interferon than did blood cells from the same subjects before the weeks of tea drinking. Blood tests and bacteria challenges showed there was no change in the interferon levels of the coffee drinkers, he said.
Bukowski said it may be possible to further isolate and refine L-theanine from tea and use that as a drug to boost the infection defense of the body.
Tea has been linked to lower heart disease and cancer risk through the action of flavonoids, a type of antioxidant.
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