In a study to establish whether green tea has anti-cancerous potential in human stomach and colon cancers, six cancerous and six non-cancerous adjacent human gastric tissues and seven cancerous and seven non-cancerous adjacent colon tissues were obtained from patients who underwent surgery for stomach and colon cancer in the Ankara University Faculty of Medicine, Department of General Surgery, Turkey. The tissues were treated with aqueous green tea extract at three different final concentrations (0.05%, 0.5%, and 1.25%) for one hour. Activity assays were performed on the same samples without green tea extract. Protein levels of the tissues were studied and adjusted to equal concentrations.

Xanthine oxidase (XO) and reduced adenosine deaminase (ADA) enzyme activities were measured before and after the incubation period. Percentage changes for the three different concentrations of green tea extract versus no green tea extract were calculated.

In both cancerous and non-cancerous tissues, XO activities were found to increase in correlation with increased extract concentrations in both cancer types. Additionally, ADA activity was found to decrease in the cancerous part of stomach tissue and to increase in the non-cancerous part.

"[While] further in vivo studies should be conducted about the effects of green tea in colon and gastric cancers, our study suggests that green tea consumption may promote cancer-preventive effects in people at risk for cancer, in addition to supporting the medical treatment of some kinds of cancers," the authors said.

From the May 27, 2008, Prepared Foods e-Flash