November 15/Washington/Hindustan Times -- A diet rich in grapes may help prevent the onset of colorectal cancer, the third most common form of cancer that kills over half a million people worldwide each year.

A study undertaken by researchers at the University of California, Irvine, showed that resveratrol, a nutritional supplement derived from grape extract, blocks a cellular signalling pathway known as the WNT pathway.

The WNT pathway is linked to more than 85% of sporadic colon cancers.

In the study, one group of participants was given 20mg of resveratrol daily in pill form. A second group of participants drank 120g of grape powder mixed in water every day, while a third group drank 80g of grape powder daily.

As the supplements did not have an impact on existing tumors, biopsied colon tissue showed that WNT signalling in the patients taking 80g of grape powder was significantly reduced, while similar changes were not seen in patients taking higher dose of grape powder or resveratrol pills.

Though the researchers were not certain why the lower dose of grape powder was more effective than the higher one, they believe that active components in grapes may have different effects in low doses as opposed to higher doses.

"This is truly exciting, because it suggests that substances in grapes can block a key intracellular signalling pathway involved in the development of colon cancer before a tumor develops," said Dr. Randall Holcombe, director of Clinical Research at the Chao Family Comprehensive Cancer Center at UC Irvine.

The study involved the participation of 499 colorectal cancer patients. The authors found that 75% of the patients were alive after 10 years of initial diagnosis, compared to 47% of the patients who did not regularly drink wine.

"Our epidemiologic study suggests that wine consumption may influence survival among a subset of colorectal cancer patients, specifically those with family history of the disease," said Dr. Jason Zell, assistant clinical professor of medicine at UC Irvine.

"These findings could reflect unique genetic and environmental interactions among familial colorectal cancer patients, but further studies are needed to test this theory. Studies such as Dr. Holcombe's with grape powder extract and resveratrol are important as they offer potential explanations for our findings," he added.

"These findings suggest that we should do additional research and clinical studies on grapes and other natural products that may prove effective in helping to prevent cancer," said Holcombe.

From the November 19, 2007, Prepared Foods e-Flash