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Green Tea Extract & Cancer

Dec 15, 2010 | By Stephen Christensen
Green Tea Extract & Cancer
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Green tea has been credited with a variety of health benefits, including weight loss, stroke and heart attack prevention, treatment of genital warts, cholesterol control and cancer prevention. According to a 2006 study in "The Journal of the American Medical Association," consumption of green tea reduces mortality from all causes combined, but not from cancer alone. Although the scientific evidence is intriguing, you should ask your doctor if green tea extracts are appropriate for you.

Active Ingredients

A variety of substances in green tea could account for its health benefits, including caffeine, theaflavins, theobromine and polyphenols. A 2006 review of green tea's properties, published in the "Journal of the American College of Nutrition," cites green tea's polyphenols, specifically catechins such as epigallocatechin-3-gallate, or EGCG, as the basis for its salubrious effects. Most green tea extracts are standardized to their EGCG content.

Cancer Epidemiology

Epidemiologic studies show that people who regularly consume green tea have a lower risk for developing a variety of cancers. However, many of these studies were performed in specific populations, such as Japanese women, whose genetic makeup may protect them from certain cancers. Interestingly, even though green tea might protect you from developing cancer, studies do not indicate that drinking green tea reduces cancer mortality. Furthermore, at least one study, published in 2009 in the journal "Blood," demonstrates that green tea interferes with certain types of cancer chemotherapy. Therefore, green tea may not be a good choice in some situations.

Breast Cancer

Asian women who follow traditional dietary patterns exhibit a lower incidence of breast cancer than women in Western countries. When these women adopt Western lifestyles, their breast cancer risk increases. Although heightened breast cancer risk could be explained by a number of lifestyle factors, analysis of epidemiologic studies shows a reduction in breast cancer risk among women who regularly consume green tea. However, green tea cannot be considered a preventive for breast cancer.

Gastrointestinal Cancer

Two studies, both published in the journal "Carcinogenesis," showed a decreased risk for cancers of the colon, esophagus and stomach among individuals who drank large amounts of green tea. These studies were conducted in large populations of Japanese and Chinese adults, so extrapolation to other demographic groups should be approached with caution. Green tea has not been shown to prevent gastrointestinal cancers.

Prostate Cancer

A 2006 "Cancer Research" study demonstrated that men who had early evidence of prostate cancer may have benefited from consuming green tea catechins. Other studies have shown reduced risk for advanced prostate cancer in men who regularly consume green tea, but it has not been unequivocally shown that green tea prevents prostate cancer.

Considerations

Large epidemiologic studies and meta-analyses of completed clinical trials show that green tea may confer health benefits in humans, including reducing the risk for certain types of cancer. However, it is uncertain if these findings can be applied to all demographic groups, and it is not clear if all the benefits of frequent green tea consumption can also be obtained from the use of green tea extracts. Green tea may not be appropriate for everyone, and expectations of benefits should not overreach scientific evidence.

References

Article reviewed by Holland Hammond Last updated on: Dec 15, 2010

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