Grape Powder Shown to Block a Cancer Gene

A study led by Dr. Randall Holcombe, director of clinical research at the Chao Family Comprehensive Cancer Center at UC Irvine, found that a diet containing low doses of freeze-dried grape powder may block the genes linked to the development of sporadic colorectal cancer.
Sporadic colorectal cancer, the third most common cancer, kills over half a million people each year. Seventy-five percent of colon cancer is sporadic and occurs in those with little or no family history of the disease.
The study showed that Resveratrol, a nutritional supplement derived from grape extract, blocks the Wnt pathway, which has been linked to over 85 percent of sporadic colon cancer. The natural chemical Resveratrol is most commonly found in grape skins but can also be found in wine and peanuts.
Holcombe and his colleagues conducted their study with 499 colon cancer patients, were divided into three groups. The first group was directed to take 20 milligrams of Resveratrol in a pill form daily. The second group drank 120 grams of grape powder mixed with water per day, while the third group only consumed 80 grams.
A biopsied colon tissue sample showed that Wnt signaling was dramatically reduced in the patients who consumed 80 grams of grape powder per day, which is equal to a half a glass of wine. These changes were not seen in the other groups.
Researchers are still unsure why the lower doses seemed the most effective in patients. Holcombe and his colleagues recently began designing a clinical cancer prevention study to see how a daily diet including one pound of grapes affects Wnt signaling.
Holcombe and his team of scientists presented their results at the Society for Integrative Oncology’s Fourth International Conference in San Francisco on Nov. 16. Calling the discovery ‘truly exciting,’ Holcombe explained that the substance found in grapes can block the Wnt pathway before a tumor develops.
An epidemiological survey following the study was given by Holcombe, Dr. Jason Zell, assistant clinical professor at UCI, and Dr. Hoda Anton-Culver, chair of UCI’s Cancer Surveillance Program. The results showed increased survival odds among patients with a family history of colon cancer who consumed wine at moderate levels before developing the cancer.
These results were featured in the October 2007 issue of Nutrition and Cancer. The researchers claimed that 75 percent of colon cancer patients who drank wine regularly were alive 10 years after being diagnosed with the cancer, compared to just 47 percent of patients who did not consume wine regularly.
‘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. 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,’ Zell said.
Holcombe claimed that researchers have known about the link between diet and cancer for some time. The study has received support from the California Table Grape Commission and the UCLA Bionutrition Unit.