Green tea’s promise of cancer prevention grows

Green tea may be considered a little woo-woo by some mainstream cancer experts but the popular beverage continues to creep toward credibility as a weapon against many forms of the disease. The best studies to date hint that green tea may help ward off cancers of the breast and prostate. And this week oral cancer came one step closer to making the list. Nearly 30,000 Americans will be diagnosed with oral cancer this year, and, with the 5-year survival rate at less than 50%, a little good news is always worth noting.

To get the most oomph out of green tea, most scientists work with a concentrated version called green tea extract (or GTE for short). Like the drink, green tea extract is chock full of polyphenols, plant substances that act as powerful antioxidants in the body. The star player on green tea’s polyphenol team is EGCG (epigallocatechin 2-gallate), a potent slayer of cancer cells.

The new study, appearing in Cancer Prevention Research, suggests that people most at risk of developing oral cancer may benefit from taking green tea extract, especially in higher doses. For the randomized, placebo-controlled trial, researchers at the University of Texas MD Anderson Cancer Center recruited 41 people with pre-cancerous lesions in their mouths. (Heavy use of alcohol and tobacco are the two main risk factors for oral cancers.)

The participants were randomly split into four groups. Three of the groups took green tea extract in various dosages—500 mg, 750 mg, and 1,000 mg—three times a day. The fourth group took a placebo. During the study, the volunteers had two biopsies, one at baseline and one at 12 weeks, to help the scientists figure out whether or not the GTE was working and, if so, how.

At study’s end, nearly 60% of those swallowing the highest doses of GTE—roughly the equivalent of drinking 8 to 10 cups of green tea daily—showed a clinical response, meaning their pre-cancerous lesions looked less menacing, compared to only 18% among those downing placebos. “While still very early, these results certainly encourage more study for patients at highest risk of oral cancer,” says Vassiliki Papadimitrakopoulou, MD, the study’s senior author. “The extract’s lack of toxicity is attractive.”


Time Magazine, 05.11.2009

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