Lee Swanson Research Update

How Green Tea Fights Cancer

August 2005

green tea

Scientists have known for some time that a compound in green tea known as epigallocatechin gallate (EGCG) helps fight cancer. How the compound fights the disease has remained a mystery—until now. A team of English and Spanish scientists recently discovered the mechanism behind EGCG's anti-cancer activity. Their findings, which were published in the journal Cancer Research, showed that EGCG prevents cancer cells from growing by binding to a specific enzyme.

Green tea catechins have long been known to exhibit a range of biological activities. Of the catechins, EGCG has been the most extensively studied, according to the report, because of its "high abundance and strong epidemiologic evidence for cancer prevention," though it is probably just one of a number of anti-cancer mechanisms in green tea. EGCG has been shown in vitro to inhibit the growth of various cancers including prostate, lymphoma, colon and lung.

Researchers discovered that EGCG works against cancer by binding to and inhibiting the enzyme dihydrofolate reductase (DHFR). Inhibition of DHFR results in a disruption of DHA biosynthesis—in other words, it stops cell growth. The setback is that DHFR is essential to both healthy and cancer cell development. In the study researchers found that in vitro and in vivo, EGCG binds strongly to DHFR, but not too tightly, so the side effects to healthy cells are not severe. Moreover, EGCG acted as a DHFR inhibitor at concentrations usually found in the blood of tea drinkers.

Cancer Research 65:1059-2064, 2005

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