Last month, researchers at Yale University School of Medicine weighed in on the issue with a review article that looked at more than 100 studies on the health benefits of green tea.

More studies are needed, they said. But they pointed to what they called an "Asian paradox," which refers to lower rates of heart disease and cancer in Asia despite high rates of cigarette smoking.

They theorized that the 1.2 liters of green tea that is consumed by many Asians each day provides high levels of polyphenols and other antioxidants.

These compounds may work in several ways to improve cardiovascular health, including preventing blood platelets from sticking together and improving cholesterol levels, said the researchers, whose study appeared in the May issue of the Journal of the American College of Surgeons.

Specifically, green tea may prevent the oxidation of LDL cholesterol (the bad kind), which, in turn, can reduce the buildup of plaque in arteries, the researchers wrote.

It may be difficult for Americans to consume as much green tea as Asians, but they can get greater amounts of antioxidants in their diet by drinking some green tea, as well as increasing consumption of dark fruits and vegetables, drinking moderate amounts of red wine and even eating some dark chocolate, said lead author Bauer Sumpio, a professor of vascular surgery at Yale.

"The collective intake probably is of significant protection to cardiovascular disease," he said.

Sumpio said what swayed him is laboratory research on cells showing that green tea can act in a way that prevents heart disease and cancer.

"For me, there is no downside to drinking green tea," he said. "It's not like red wine with the alcohol issue."

Sumpio and his co-authors concluded in the article that "the evidence is strong that green tea consumption is a useful dietary habit to lower the risk (for) and treat a number of chronic diseases. ... The consumption of six to 10 cups of tea per day might constitute an aid to increased health, longevity and quality of life."