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Evidence For Green Tea Mounts

Study found it held off breast cancer in rats

TUESDAY, June 24, 2001 (HealthDayNews) -- A new study adds a tantalizing possibility to green tea's potential cancer-fighting abilities.

Several previous studies have shown the drink helps protect against a variety of cancers, while other studies found it makes no difference.

Now researchers at Boston University say the highly touted tea held off breast cancer in rats.

The scientists fed 15 rats green tea, along with a chemical known to induce breast cancer. Compared to 15 other rats that were fed plain water with the chemical, the tea-drinking rats took longer to develop tumors. And the tumors weighed, on average, 70 percent less.

"It was surprising we saw such a dramatic difference," says lead author Gail Sonenshein, a biochemistry professor at Boston University School of Medicine. The study appears in the July issue of the Journal of Cellular Biology.

Sonenshein says it's too early to recommend that women start drinking green tea as a cancer preventive.

"But personally, I drink green tea in the afternoon," she adds. "I don't know yet if it works for prevention, but there is enough research to indicate it does that I drink it."

Green tea is full of molecules called polyphenols, which have inhibited tumor cell growth in animals through their antioxidant activity. Antioxidants protect against cell damage, which can be a precursor to cancer.

Other research hasn't been this optimistic. In one recent study, after adjusting for smoking and other factors, researchers found people who said they drank green tea regularly had the same risk of getting gastric cancer as those who didn't. That study appeared in The New England Journal of Medicine.

In the lab, polyphenols have been shown to be potent antioxidants, even stronger than vitamins E or C, says Marji McCullough, a nutritional epidemiologist for the American Cancer Society.

But outside the lab, "the evidence is not strong that green tea has a preventative effect against cancer," McCullough says. "The data is inconsistent, both from an animal model and a human model."

McCullough adds, however, that it's worthwhile to continue to test green tea because there's very little chance it will do any harm.

In the most recent study, researchers fed the 30 rats a carcinogenic compound that previous research has shown leads to breast cancer within nine to 12 weeks in an overwhelming majority of cases.

After a few weeks, researchers began feeling the rats' mammary glands for tumors. Researchers could feel tumors, on average, two weeks later in the tea-fed rats than in the water-fed rats.

"We cannot distinguish absolutely if there was cancer present because we weren't looking at cell changes in the molecular level," Sonenshein adds.

After 17 weeks, the tumors in the tea-fed rats weighed 70 percent less than those in the water-fed rats.

Breast cancer is the second-leading cause of cancer death among U.S. women, according to the American Cancer Society.

What To Do: For more information on nutrition and cancer, visit the American Institute for Cancer Research. For more information on breast cancer, visit the American Cancer Society.

SOURCES: Interviews with Gail Sonenshein, Ph.D., biochemistry professor, Boston University School of Medicine, Boston; Marji McCullough, Sc.D, nutritional epidemiologist, American Cancer Society, Atlanta; July 2001 Journal of Cellular Biology
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