An antioxidant found in green tea is at least 100 times more effective than vitamin C and 25 times better than vitamin E at protecting cells and their genetic material, DNA, from damage believed to be linked to cancer, heart disease and other potentially life-threatening illnesses, KU research shows.
The antioxidant, known as epigallocatechin gallate, or EGCG, carries twice the antioxidant punch of resveratrol, found in red wine, according to the study. EGCG also is present in black and oolong tea, although in lower concentrations.
Lester A. Mitscher, university distinguished professor of medicinal chemistry at KU, reported on the research today, Sept. 11, at the 214th American Chemical Spciety national meeting in Las Vegas. Delbert Shankel, KU professor emeritus of microbiology, and Segaran P. Pillai, a KU postdoctoral research scientist in medicinal chemistry, also participated in the research.
In recent years, several studies in animals and humans have suggested that green tea may help prevent certain human illnesses.
The KU research is believed to be the first to actually quantify the effectiveness of green tea's disease-fighting capabilities and measure it against other popular antioxidants. Antioxidants appear to help protect human cells from attack by free radicals, which are unstable molecules generated by the body.
"Our research shows that green tea contains a powerful antioxidant, known as epigallocatechin gallate or EGCG, that actually gets into cells to exert its protective effect," Mitscher says. "I'm not making any claims, but, used in conjunction with a healthful diet and exercise program, it's like an insurance policy. It increases your odds of avoiding or postponing diseases associated with free radicals."
Other protective antioxidants are also present in teas, although not in as great of amounts as EGCG is.
For the KU study, hundreds of samples of green, black and oolong tea and other known antioxidants were analyzed in varying doses, using a modified version of the Ames test. The test, developed by Bruce Ames, a University of California, Berkeley, researcher, is widely used to detect cellular mutations.
Mitscher was so impressed by the results of the research, conducted this spring, that he now takes a nutritional supplement containing the antioxidant compounds found in green tea. (The KU tests show that nutritional supplements containing the antioxidants vary in their effectiveness.) Green tea, which is water soluble, has another advantage over vitamin E, he adds. Excessive amounts of antioxidants found in green tea are excreted by the body. The body absorbs and retains fat-based vitamins such as vitamin E, even at potentially harmful levels.
Though Mitscher won't guarantee that green tea can prevent cancer and heart disease, statistics suggest that it may postpone the diseases for five years or more, he says.
"By the time we are in our 80s, it's an exceptional person who has not had cancer," Mitscher says. "That's why it's important for us to look at the kinds of compounds that may stall the development of disease."
Mitscher notes that black tea, the tea most commonly consumed by Americans, and oolong tea do not have the same antioxidant potency as green tea.
That's because green tea is steamed immediately after it is picked, which prevents the leaves from oxidizing, thus preserving the EGCG. In comparison, black and oolong tea have less than half the levels of EGCG as green tea, Mitscher says.
The KU research was funded by a grant from Pharmanex, which produces plant-based health-care products, including a nutritional supplement that contains antioxidants found in green tea.