The conclusions of the study, published in the American medical journal Cancer Research, lend weight to previous surveys that found lower cancer rates among populations of heavy green tea drinkers. This may be because EGCG blocks an enzyme that is a catalyst to cancer growth; in fact, it has properties similar to those of methotrexate, a drug that has been used for decades in the treatment of cancerous breast, head and neck, and lung tumors. "For the first time we have a scientific explanation of why EGCG inhibits the growth of cancer cells at concentrations which are found in the blood of people who drink two to three cups of green tea a day," says Professor Roger Thorneley, one of the joint research team members.
Scientists hope their findings will lead to EGCG-based drugs that have fewer side effects than methotrexate, which can cause vomiting and hair loss, among other ills. But as is often the case with promising medical discoveries, there are caveats. Excessive drinking of green tea by pregnant women has been linked to birth defects. And Thorneley warns that it could take up to 10 years to develop and start to test new treatments. In the meantime, a couple of daily cups of cha can't hurt. "I usually only have a sip of my wife's green tea," says Thorneley, "I might start drinking it now."