"Tea helps fight infection"

"The [study] results gave clear proof that five cups of tea a day sharpened the body's disease defenses, said Dr. Jack F. Bukowski, a researcher at Brigham and Women's Hospital in Boston and Harvard Medical School.

Dr. Bukowski and his co-authors isolated a substance called L-theanine from ordinary black tea. He said L-theanine was broken down in the liver to ethylamine, a molecule that primes the response of an immune system element called the gamma-delta T cell."

New York Times, April 22, 2003