LIFE EXTENSION UPDATE
Oral Green Tea Polyphenols Inhibit Prostate Cancer In Mouse Model
Scientists at Case Western Reserve University & The Research Institute of University Hospitals of Cleveland, in Cleveland, Ohio, utilized a mouse model genetically engineered to develop metastatic prostate cancer in 100% of the animals to test the effects of orally administered green tea against development of the disease. In a study published in the August 28, 2001 issue of the Proceedings of the National Academy of Sciences,(http://www.pnas.org/
) researchers documented the effect of giving the amount of green tea polyphenols equivalent to six cups of green tea per day in humans, to male mice in several experiments. In the first two experiments, twenty-eight week old mice were divided into two groups. One group received drinking water that contained 1% green tea polyphenols for twenty-four weeks as their sole source of fluid, while the control group received tap water.
The polyphenol infusion consisted of 62% epigallocatechin-3-gallate, 24% epicatechin-3-gallate, 6% epicatechin, 5% epigallocatchin and 1% caffeine. At the conclusion of the studies, the animals' prostates were removed and examined. The same procedure was followed in the third experiment which was conducted on thirty-six mice at eight weeks of age, however, they were allowed to survive into old age before the experiment was concluded.
The mice were examined by MRI for tumor growth at twenty and thirty weeks of age. At twenty weeks, mice not given green tea polyphenols had prostate tumors, which were fully developed by thirty weeks. The mice given green tea polyphenols experienced an average 44% reduction in prostate cancer growth compared to the controls at twenty weeks, and a 42% reduction at thirty weeks. In the first two experiments, green tea polyphenols resulted in an almost complete inhibition of distant site metastases, whereas 95% of untreated mice had lymph node metastases. It also increased tumor free survival, with half the animals receiving the polyphenols remaining tumor free at forty weeks old, and life expectancy, which was 70% higher in mice given the polyphenol-enhanced drinking water. Green tea polyphenols were also found to inhibit serum IGF-1 levels. According to some studies, IGF-1 levels could be better predictors of prostate cancer risk than PSA levels.
Green tea's mechanism of action is believed by the researchers to be that of inducing apoptosis in prostate cancer cells observed in this study, however they recommend further studies to confirm this.
Because prostate cancer is typically diagnosed in older men, the study's authors comment that the disease is an excellent candidate for prevention, because even a modest delay in the development of the disease could result in a substantial reduction in the number of patients diagnosed. They write, "We suggest that regular consumption of green tea may prlong life expectancy and quality of life in prostate cancer patients."
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