A French-led international team of scientists says it has discovered how polyphenols in red wine and green tea inhibit prostate cancer growth. The scientists -- who say their findings might lead to a major advance in the treatment of prostate cancer -- said they discovered antioxidants in red wine and green tea disrupt an important cell-signaling pathway necessary for prostate cancer growth. The researchers, led by the French National Institute of Health and Medical Research in Paris, said their findings that appear in the early online edition of The FASEB Journal, might lead to the development of drugs that could stop or slow cancer progression, or improve current treatments. "Not only does (the) signaling pathway play a role in prostate cancer, but it also plays a role in other cancers, such as colon cancer, breast cancer and gastric cancers," said Dr. Gerald Weissmann, editor-in-chief of The FASEB Journal. In the experiment, three groups of mice were given drinking water, drinking water with a green tea compound known as EGCg, or drinking water with a different green tea compound, polyphenon E. Then human prostate cancer cells were implanted in the mice. The results showed a dramatic decrease in tumor size in the mice drinking the green tea mixtures. "The profound impact the antioxidants in red wine and green tea have on our bodies is more than anyone would have dreamt just 25 years ago," Weissmann said. "As long as they are taken in moderation, all signs show that red wine and green tea may be ranked among the most potent 'health foods' we know."

Researchers at Arizona Cancer Center, University of Arizona, suggest that a green tea concentrate may help some people boost their metabolic defense against toxins capable of causing cancer. In a study of 42 people, the concentrate, composed of chemicals known as green tea catechins in amounts equal to that found in 8-16 cups of green tea, boosted production of the enzymes, which belong to the glutathione S-transferase (GST) family, by as much as 80 percent in some participants. GST enzymes are believed to be crucial to the body's defense against cancer-causing chemicals and other toxins, according to the study's lead investigator, H.-H. Sherry Chow, Ph.D., a research associate professor at the University of Arizona. "They actually convert known carcinogens to non-toxic chemicals, and studies have shown a correlation between deficient expression of these enzymes and increased risk of developing some cancers," Chow said. "Expression of this enzyme varies dramatically in people due to genetic variation and environmental factors," Chow added. "Green tea catechins somehow increase gene expression of these enzymes, which can be an advantage to people with low levels to start with," he added. The study was intended to see if green tea catechin concentrate had any effect on the levels of GST enzymes in healthy individuals, an examination that could explain the tea's anti-cancer properties. Healthy volunteers were asked to abstain from consuming any tea or tea-related products for four weeks and then blood was drawn and baseline GST enzyme levels were determined. After taking the green tea concentrate for four weeks, a second blood test was taken. Researchers found that little variation occurred for those with high or medium GST levels. But it had its most significant effect in volunteers whose baseline blood measurements showed low GST activity, an 80 percent increase compared to baseline GST activity. "This is the first clinical study to show proof that chemicals in green tea can increase detoxification enzymes in humans. There may be other mechanism in play by which green tea may protect against cancer development, but this is a good place to start," Chow said. The study is published in the August issue of Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research.

Laboratory studies have found that green tea extracts prevent the growth of prostate cancer cells in test tubes. In a large clinical study conducted in Southeast China researchers found that the risk of prostate cancer declined with increasing frequency, duration and quantity of green tea consumption. However, both green and black tea extracts also stimulated genes that cause cells to be less sensitive to chemotherapy drugs. Given this potential interaction, people should not drink black and green tea (as well as extracts of these teas) while receiving chemotherapy.

In the first known study of the absorption and anti-tumor effects of green and black tea polyphenols in human tissue, researchers at the University of California at Los Angeles were able to detect tea polyphenols in prostate tissue after a very limited consumption of tea. The study was reported at Experimental Biology 2004, in Washington, D.C., as part of the scientific program of the American Society of Nutritional Sciences, one of the six sponsoring scientific societies of this large multi-disciplinary meeting. The scientists found that prostate cancer cells grew more slowly when placed in a medium containing blood serum of men who had consumed either green or black tea for five days compared to serum collected before the men began their tea-drinking regimen. Serum from men who drank comparable amounts of diet or regular soda showed no such slowing in cancer cell proliferation.

Research by Curtin University in Perth Western Australia has shown Green tea drinking over a long period of time helps prevent prostate cancer. Professor Colin Binns studied long time drinkers in China. The big sippers who'd been imbibing for 20 years were 2/3 less likely to develop the cancer than the control group.

Laboratory studies have found that green tea extracts prevent the growth of prostate cancer cells in test tubes. In a large clinical study conducted in Southeast China researchers found that the risk of prostate cancer declined with increasing frequency, duration and quantity of green tea consumption. However, both green and black tea extracts also stimulated genes that cause cells to be less sensitive to chemotherapy drugs. Given this potential interaction, people should not drink black and green tea (as well as extracts of these teas) while receiving chemotherapy.