The active ingredient in green tea, epigallocatechin-3-gallate (EGCG), has been found to block the growth of bladder tumours in rats.
EGCG is increasingly regarded as an active anti-cancer agent, although most trials study its power in tea consumption. In a previous study, drinking more than five cups per day seemed to protect against the cancer.
The new study, published in the September issue of the Journal of Urology, investigated its effects when injected directly into the bladder.
Lead author Dr J. Karl Kemberling and colleagues, from the Medical College of Ohio in Toledo, US identified a dose of the green tea chemical that could kill all cancer cells after two hours of incubation.
The authors then tested EGCG on rats with tumour cells implanted in their bladders. Thirty minutes after tumour cells were injected, they treated half the rats with EGCG. The others were not treated.
Sixty-four per cent of animals treated with EGCG were free of tumours when examined three weeks later, the researchers reported, while all of the untreated animals showed tumour growth.
Green tea's anti-cancer effects have been attributed to its high antioxidant content, but researchers recently reported that it could instead be a result of the chemicals shutting down the aryl hydrocarbon (AH) receptor in cancerous cells.