Cancer
Study: Green tea protects against colorectal cancer
By David Liu
Dec 9, 2007 - 6:56:11 PM

SUNDAY DEC 9, 2007 (Foodconsumer.org) -- Drinking four to six cups of green tea a day may dramatically reduce the risk of colorectal cancer in humans, according to an animal study presented at the Sixth International Conference on Frontiers in Cancer Prevention, sponsored by the American Association for Cancer Research.

In the study, Dr. Hang Xiao at the Ernest Mario School of Pharmacy at Rutgers University, Piscataway, New Jersey and colleagues found a standardized green tea polyphenol preparation called Polyphenon E inhibits the growth of colorectal tumors in rats treated with a carcinogen.

"Our findings show that rats fed a diet containing Polyphenon E are less than half as likely to develop colon cancer," Dr. Hang Xiao said in a statement.

The study was consistent with some previous studies that have showed that green tea consumption was associated with lower colon cancer risk.

In the current study, Xiao and team injected rats with azoxymethane, a chemical known to cause colorectal tumors that mimic human colorectal cancer in many characteristics.  

Afterwards, one group of rats was fed a high fat Western-style diet and another with Polyphenon E for 34 weeks.  The dose rats received was equivalent to four to six cups of green each day for humans.

Xiao and colleagues found Polyphenon E not only decreased the total number of tumors per rat, but also decreased the tumor size, compared with control rats that received no green tea preparation.

Specifically, 67 percent of control rats that received no green tea preparation developed malignant tumors compared to only 27 percent in the rats receiving Polyphenon E.  The treated rats also reduced the number of tumors by 80 percent compared to the control groups.

Xiao noted that considerable amounts of tea polyphenols were found in the samples from treated rats. The levels of the compounds were comparable to the amount found in people who ingest tea leaves or tea beverage.