Tea for Tumors?

LAS VEGAS--Health conscious drinkers who sip red wine for its beneficial antioxidants may want switch their beverage of choice to a piping cup of green tea. New work presented here today at the semiannual meeting of the American Chemical Society shows that an antioxidant found in green tea is 3.5 times as effective as the antioxidant in red wine and more than 100 times as effective as vitamin C at protecting cells and DNA from damage believed to be linked to cancer.

Antioxidants are widely believed to protect cells by sopping up highly reactive compounds known as free radicals before they have a chance to react and tear apart DNA or other vital cellular components. Left unchecked, such damage can lead to genetic mutations that can trigger cancer. Antioxidants are common in fruits, vegetables, red wine, and even peanuts. Tea leaves also contain a variety of compounds that have been shown to have antioxidant properties. But although animal studies have suggested that tea can protect against diseases such as skin and stomach cancer, the antioxidants in tea had not been directly compared to those found in other foods.

Medicinal chemist Lester Mitscher and his colleagues at the University of Kansas, Lawrence decided to test a number of possible antioxidant compounds in green tea, red wine, and vitamins C and E for their ability to prevent bacterial cells from mutating, a standard test for gauging a compound's anticancer capabilities. In one of many tests, the Kansas researchers incubated bacterial cultures with hydrogen peroxide, a powerful free radical producer, along with varying concentrations of one of several antioxidants.

All of the antioxidants helped reduce the mutation rates, but the clear winner turned out to be the most abundant antioxidant in green tea, known as epigallocatechin gallate (EGCG). While EGCG protected about 68% of the cells from oxidative damage, resveratrol--the antioxidant in red wine--protected only 20%, vitamin E protected 1.5% and vitamin C protected only 0.6%. "Of all the antioxidants we've measured, EGCG wins," says Mitscher.

"There's no question it's important work," says A. Douglas Kinghorn, a pharmacologist at the University of Illinois, Chicago, who says the finding could partly explain the low rates of some cancers in Japan. Mitscher cautions that this result does not show that the potent green tea antioxidants stave off cancer. Nevertheless, he adds, "it has made a believer out of me."