It is all preliminary -- much of the scientific work has been done on animals in other countries -- but there is some evidence that drinking tea may help stave off cancer and lower cholesterol.
Research from one study presented at the International Tea Symposium in New York earlier this year indicates that zTC consumption of Chinese green tea inhibits esophageal cancer in rats. Another paper shows that the main constituent of Japanese green tea (epigallocatechin gallate, or EGCG) seems to prevent cancerous skin tumors in mice and apparently has lowered the incidence of gastric cancer in some Japanese people who consume it in large quantities.
Although some experiments showed that drinking green tea was tied to lower blood cholesterol and lower blood pressure, researchers were reluctant to draw firm conclusions because of other mitigating factors in the experiments. Tea consumption, however, does not appear to raise cholesterol levels.
"The data are suggestive that people who drink tea have [a] somewhat lower [occurrence] of heart problems," said Dr. John Weisburger, director emeritus of the American Health Foundation, an independent nonprofit research organization, and co-chairman of the symposium.
Green tea differs from the more common black tea in that the newly harvested leaves are heated to prevent the oxidation of polyphenols, the main biologically active ingredient of tea. Black tea, by far the most common form, is air-dried to promote the oxidation of polyphenols. There has not been enough research to determine whether the oxidized polyphenols of black tea have the same action in the body as the unoxidized polyphenols of the green tea, researchers said.
The symposium, sponsored by the American Health Foundation and the Tea Council and the Tea Association of the USA, was the first international scientific conference ever held on the health benefits of tea.
Dr. Weisburger stresses that more research is needed on humans, with tea drinkers and non-drinkers, particularly those living in the United States, who have their own particular habits.
"When you consider that, besides water, tea is the most widely consumed beverage in the world, it becomes clear that the potential public health implications might be enormous," said Dr. George Christakis, adjunct professor at the University of Miami School of Medicine and conference co-chairman.