Lee Swanson Research Update

Green Tea May Cut the Risk of Gastric Cancer in Women

March 2008

The green tea polyphenol (-)-epicatechin-3-gallate (ECG) may slash the risk of gastric cancer among women by 75%, a new study from Japan suggests.

While that's great new for women, researchers from the National Cancer Center in Tokyo cautioned that increased blood levels of the polyphenol can have the opposite effect in men and may increase their risk.

The researchers, led by Shizuka Sasazuki, reported their findings in the journal Cancer Epidemiology, Biomarkers & Prevention.

The study adds to an ever-growing body of science supporting potential health benefits of green tea and its polyphenols, previously linked to a lower risk of certain cancers, weight-loss, heart health and protection against Alzheimer's.

Green tea contains between 30% and 40% of water-extractable polyphenols, while black tea (green tea that has been oxidized by fermentation) contains between 3% and 10%. The four primary polyphenols found in fresh tea leaves are epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG) and epicatechin (EC).

The new study, which used a case-control design, matched 494 people with gastric cancer (cases) with 494 healthy people (controls). Blood samples were taken and polyphenol levels measured using high-performance liquid chromatography (HPLC).

Sasazuki and coworkers reported that blood levels of ECG between 0.32 and 9.2 ng/mL were not associated with any change in gastric cancer risk among women. However, blood levels of 9.3 ng/mL were associated with a 75% reduction in risk in women, compared to women with blood levels below the detectable limit. On the other hand, “for men, a high plasma level of (-)-epigallocatechin was associated with an increased risk of gastric cancer,” the researchers said.

Cancer Epidemiology, Biomarkers & Prevention 17(2):343-351, 2008

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