Green tea, made from unfermented leaves of Camellia sinensis, contains higher levels of polyphenols and lower levels of caffeine than black tea, which comes from the same plant. The polyphenols in green tea are responsible for its bitter flavor and tremendous health-boosting qualities. Recent research on green tea has yielded promising results for its benefits in the prevention and treatment of several types of cancer.
Combination Therapy
Green tea enhances the effectiveness of some cancer drugs, according to a study published in the November 2010 "Cancer Science" journal on the potential benefits of combination therapy of green tea with anticancer drugs for cancer treatment. The study, conducted at the Research Institute for Clinical Oncology, Tokushima Bunri University, Japan, found that the green tea polyphenol epigallocatechin gallate, in combination with anticancer drugs -- including tamoxifen, COX-2 inhibitors, and retinoids -- produced a synergistic enhancement of apoptosis, or programmed cell death, and cancer gene expression in lung cancer cells.
Genetics
If you possess a certain gene, you may derive greater protection against cancer when you use green tea, according to a study conducted at the School of Public Health, University of Minnesota. The study, published in the 2010 "International Journal of Molecular Epidemiology and Genetics," found that people with a slow-acting form of the enzyme catechol-O-methyltransferase retain more of the protective polyphenols, resulting in greater anticancer benefits. Women with the gene are less likely to develop breast cancer, say the authors.
Stomach Cancer
Green tea reduces risk of stomach cancer, according to a meta-analysis -- a review of previously published research -- conducted at Yonsei University, Seoul, Korea. Five or more cups of green tea per day confers a significant protective effect, reported the authors of the study, published in the April 2010 "Epidemiolgy and Health." The results suggest that higher levels of green tea may be needed in order to achieve a protective dose; however, the authors cautioned that biases inherent in a meta-analysis type of study may lead to inaccurate conclusions.
Prostate Cancer
Prostate cancer may respond well to treatment with green tea polyphenols, according to a study conducted at the University of Wisconsin. In the study, epigallocatechin-3-gallate, the major polyphenol in green tea, suppressed cancer cell reproduction in laboratory mice. The green tea extract also decreased activity of a cancer gene activated by testosterone and increased expression of a tumor suppressor gene, say the researchers of the study, published in the December 2010 "Federation of American Societies for Experimental Biology."
References
- PubMed.gov: New cancer treatment strategy using combination of green tea catechins and anticancer drugs
- PubMed.gov: Genetic Association Between the COMT Genotype and Urinary Levels of Tea Polyphenols and Their Metabolites among Daily Green Tea Drinkers
- PubMed.gov: Green Tea Consumption and Stomach Cancer Risk: A Meta-Analysis
- PubMed.gov: Green tea polyphenol EGCG blunts androgen receptor function in prostate cancer
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