The Tao of Tea
Tempest in a Teapot
Reality Check continued...
"Scientists can always say something remains to be
proven," says Lenore Arab, PhD, professor of epidemiology and nutrition at
the University of North Carolina at Chapel Hill School of Public Health.
Studying the effects of tea is difficult because the pattern of
consumption varies from country to country -- and even within countries. And
understanding the long-term health effects of tea requires long-term studies,
In spite of the difficulties, there is a "large and
convincing body of evidence that tea is chemo-preventive," Arab tells
WebMD. "What has impressed me most recently is the accumulating evidence of
tea's protective role in prostate cancer."
And now Arab says she and other tea researchers are seeing a
protective effect against colon and rectal cancer among tea drinkers in
With regard to heart disease, Arab says a recent analysis
pooling the results of 12 studies looking at tea consumption in a quarter
million people, found that people who drink more green tea than others have
less incidence of heart attack. Intriguingly, that effect was greater in Europe
than in the U.S., she says.
Tea advocates say most of the health effects derive from
"polyphenols," which are the antioxidants in tea. Weisburger explains
that it is the oxidized form of cholesterol, for instance, that damages the
surfaces of veins and arteries, leading to heart disease. "It turns out
that polyphenols in tea prevent oxidation," Weisburger tells WebMD.
Weisburger was keynote speaker at this year's International
Scientific Symposium on Tea and Human Health, sponsored by the U.S. Tea Council
in Washington. A similar symposium will be held again next year, he tells
The American Cancer Society has weighed in with a cautious
statement on tea as a cancer preventive. Some animal studies have been shown to
reduce risk, "but beneficial effects in people are not proven,"
according to a 1996 ACS statement on the subject.
"It's only in the last 10 year that Western science has
tried to look at antioxidant activities of tea," says Dave Ringer, PhD,
scientific program director at the ACS. "It's a young science. Generally,
it is felt that tea can inhibit the initiation of cancer and delay its
progression in animal studies. But we don't really have large well-controlled
epidemiological studies to look at this yet [in humans], because you need to
correct for the effects of other dietary components."