Colon Cancer Genes Blocked by Grape Powder

Colon cancer is the third most common form of cancer, killing more than half a million people each year. Researchers at the University of California, Irvine, found that a substance in grapes block genes linked to the cancer, which suggests that a diet high in grapes could help prevent the disease.

The study, which was a follow up of an earlier study on resveratrol, a substance found in grapes, was conducted with colon cancer patients. One group took resveratrol in pill form, while two other groups took either 120 or 80 grams of grape powder mixed in water daily. Existing tumors were not affected, but the patients taking the 80 gram dose had less activity along a cellular signaling pathway known as the Wnt. The Wnt pathway is linked to more than 85 percent of sporadic colon cancers, the most common form, and the earlier study had shown that revseratrol had a similar effect in vitro. However, in the more recent study those changes were not seen in patients taking resveratrol or the higher dose of grape powder.

Researches believe that the active components in the grapes could have different effects at low doses, as is commonly found in nutritional studies. They also believe that other grape chemicals may be responsible for the aiding resverstrol's effect, which could be why the substance alone did not show a benefit in patients.

"This is truly exciting, because it suggests that substances in grapes can block a key intracellular signaling 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.

To consume the equivalent of 80 grams of grape powder you would have to eat one pound of grapes, or three servings according to USDA guidelines. You could also drink just one glass of red wine. The next step for researchers is designing a clinical study assessing the effect of eating 1 pound grapes a day on the Wnt pathway.

An earlier survey had also found that, in people with a family history of colorectal cancer, the patients who drank wine moderately before developing cancer had a better chance of survival than those who did not. Of those patients, 75% were alive 10 years after their first diagnosis, compared to 47% of the non-drinkers. Taht survey can be found in the October 2007 issue of Nutrition and Cancer, and was also conducted by Dr. Holcombe, Dr. Jason Zell, assistant clinical professor of medicine at UC Irvine, and Dr. Hoda Anton-Culver, director of UC Irvine's Cancer Surveillance Program and chair of epidemiology.

"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," Zell said. "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."

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University of California, Irvine, Grape Powder Blocks Genes Linked to Colon Cancer