MONDAY, Sept. 8, 2003 (HealthDayNews) -- Drink tea. Drink lots of it. Drink black tea. Drink green tea. Drink it iced, drink it hot; you might even want to rub it on your skin.
A dozen or so studies being presented Sept. 8 at the American Chemical Society meeting in New York City are reporting health benefits from the beverage that range from fighting fat to fighting cancer.
In what seems to be the first study linking immunity with tea, researchers in Boston found people who drank five to six cups of black tea each day seemed to get a boost in that part of the immune system that acts as a first line of defense against infection.
"We found that certain molecules were shared by bacteria, parasites and vegetables -- and one of the vegetables was tea," says study author Dr. Jack F. Bukowski, an assistant professor of medicine at Harvard Medical School and staff rheumatologist at Brigham and Women's Hospital. "These molecules could activate a certain component of the immune system called gamma delta T lymphocytes, which are very important as the first line of defense against infection and tumors."
Bukowski and his colleagues asked non-tea drinking, non-coffee drinking volunteers to consume five to six cups of black tea infusion or instant coffee for either two or four weeks.
They then took blood samples and tested the activity of the immune system against bacteria.
"We found that samples taken after they drank tea were able to react against the bacteria fivefold better by making a very important protein called interferon gamma," Bukowski says. "If you put two and two together, that should mean you're going to be more able to fight off diseases because that's a very important bacteria-fighting and virus- and tumor-fighting molecule, but we did not go on to show that drinking tea actually protects you against getting sick." That will be the subject of the next study.
Although the tea can't be viewed as a cure, it could be viewed "almost as a vitamin for the immune system," Bukowski says. And more of these "vitamins" will probably be found in vegetables, Bukowski adds, which means you should probably have some vegetables with your tea.
A second study found that mice who had been genetically engineered to develop prostate cancer, and who drank the equivalent of about six cups of tea a day, did not end up developing tumors. "Those animals who drank tea were substantially protected and they lived longer," says study author Hasan Mukhtar, a professor of cancer research at the University of Wisconsin in Madison. No one knows if the same mechanism will be at play in humans, but Mukhtar says he suspects that tea will have some effect in some patients.
"China has the lowest prostate cancer rate in the world and Japan is also very low, and they drink much more tea," he notes.
Another study found that a green tea extract reduced body fat in mice, possibly by inhibiting the absorption of fats and starches, and that drinking green tea may mitigate DNA damage from smokers that could lead to mouth cancer. Still other researchers are working on developing a cream made up of tea polyphenols which would ward off skin cancer.
Finally, researchers in Boston found that drinking tea improved the function of blood vessels and platelets, and may therefore reduce the risk of heart attack and stroke. This adds to an already large body of knowledge on tea and heart health.
"The results of studies on tea have been quite positive along a whole array of human ailments with the strongest appearing to be cardiovascular," says Joseph Simrany, president of the Tea Council of the U.S.A. in New York City. "Not to diminish any of the others, but cardiovascular is coming to the forefront in this point of time."