Drinking green tea is generally recognized as good for your health, though scientific studies on this have been few. However, an exciting new trial seeks to determine whether green tea can prevent colon cancer—the biggest such trial in the world to date, according to Thomas Seufferlein, director of the Department of Internal Medicine at Halle University Hospital in Germany and co-head of the research team.

The study will investigate the effect of green tea on the formation of colon polyps, sometimes seen as precancerous. German Cancer Aid, a non-profit organization that receives no public funds, is paying the entire 2.1-million-euro (2.8 million dollars) cost of the project with donations.

"In the interests of the people concerned, we need to exhaust all possibilities for cancer prevention. This includes naturopathic therapies," said German Cancer Aid spokeswoman Christiana Tschoepe.

The trial, comprising 3,000 participants, has just gotten under way. "They were recruited for a three-year trial, but since it's staggered, the last ones won't be finished until six years after the trial starts," Seufferlein said. Selected from 30 large medical practices and clinics throughout Germany, the participants have all had colon polyps removed and are seen as having an increased risk of colon cancer. Researchers also want to learn whether green tea can help prevent a recurrence of the polyps.

For simplicity's sake, the trial uses green tea in capsule form; the dosage is two capsules daily. "That's the equivalent of about five to ten cups of tea, depending on the method of preparation," noted Julia Stingl, a clinical pharmacologist at Germany's Ulm University and the other co-head of the research team. The capsules contain an extract with all of green tea's active components except caffeine, which has been removed.
One group of participants receives capsules containing green tea extract, the other takes placebo capsules. Neither the participants nor the researchers know which group is which.

"Should its effectiveness be scientifically proven, the extract could be taken affordably in liquid form as a dietary supplement," Stingl pointed out.