Tea: Antioxidants in Green, Black & Oolong Tea (cont.)
Studies of humans, animals, and Petri dish experiments show that black and green tea is highly beneficial to our health, says 82-year-old John Weisburger, PhD, senior researcher at the Institute for Cancer Prevention in Valhalla, N.Y.
"I've published over 500 papers, including a helluva lot on tea," says Weisburger, who drinks 10 cups daily. "I was the first American researcher to show that tea modifies the metabolism to detoxify harmful chemicals."
Green tea, black tea, oolong tea -- they all come from the same tea plant, Camellia sinensis; the leaves are simply processed differently, explains Weisburger. Green tea leaves are not fermented; they are withered and steamed. Black tea and oolong tea leaves undergo crushing and fermenting processes.
All teas from the Camellia tea plant are rich in polyphenols, which are antioxidants -- meaning they scavenge for cell-damaging free radicals and detoxify them, says Weisburger.
"Astounding" aptly describes tea's antioxidant power: "Whether it's green or black, tea has about 8 to 10 times the polyphenols found in fruits and vegetables," he says.
While herbal teas may also contain antioxidants, less is known about them, Weisburger adds.
"In my lab, we found that green and black tea had identical amounts of polyphenols," he tells WebMD. "We found that both types of tea blocked DNA damage associated with tobacco and other toxic chemicals. In animal studies, tea-drinking rats have less cancer."
Look at the world's big tea-drinkers, like Japan and China. "They have much less heart disease and don't have certain cancers that we in the western world suffer," says Weisburger.
However, be careful about doctoring-up your tea, says Weisburger. One study found that adding too much milk to can greatly reduce tea's health benefits.
"The scientific evidence about tea is evolving and I think it's compelling," Jeffrey Blumberg, PhD, Friedman School of Nutrition Science and Policy of Tufts University, tells WebMD.
The Evidence on Tea
Tea is a great example of the past decade's research of antioxidants, he says. "There is a pretty consistent body of evidence suggesting there is a benefit to tea. Tea is a very rich source of a specific kind of antioxidant -- flavonoids," says Blumberg.
Admittedly, there has been conflict among the studies. One large study in the American Journal of Clinical Nutrition followed nearly 40,000 women for nearly seven years. Researchers found that drinking over four cups of tea a day did nothing to reduce their risk of heart disease.
However, the bulk of research is what counts most, Blumberg says. And that research has found that regular tea drinkers -- people who drink two cups or more a day -- have less heart disease and stroke, lower total and LDL cholesterol, and that they recover from heart attacks faster.