November 23, 2007
Grapes Might Reduce Colon Cancer Risk

A moderate dose of grapes per day seems to suppress a genetic pathway involved in colon cancer development.

Led by Dr. Randall Holcombe, director of clinical research at the Chao Family Comprehensive Cancer Center at UC Irvine, the study followed up on previous in vitro studies showing that resveratrol, a nutritional supplement derived from grape extract, blocks a cellular signaling pathway known as the Wnt pathway. The Wnt pathway has been linked to more than 85 percent of sporadic colon cancers, which is the most common form of colon cancer.

The UC Irvine researchers conducted their study with colon cancer patients. One group was given 20 milligrams daily of resveratrol as a pill; another drank 120 grams daily of grape powder mixed in water; and a third drank 80 grams daily of grape powder.

While the supplements did not have an impact on existing tumors, biopsied colon tissue showed that Wnt signaling in the patients taking 80 grams of grape powder was significantly reduced. Similar changes were not seen in patients taking the higher dose of grape powder or the resveratrol pills.

So excess is not always best and the whole food has advantages over the supplement pill.

Up for a pound of grapes every day?

Eighty grams of grape powder equal a half glass of wine or 1 pound of grapes, which is equivalent to three dietary servings of grapes, according to the USDA.

The wine has alcohol that will increase your risk of some cancers. Grape juice might be more effective.

My general take on studies about specific foods is that they typically are too short in duration and each food has such limited effect that we can't tell whether eating that food for years and years will increase your odds of survival. Remember, you can reduce your risk of a single disease but as a side effect increase your risk of something else. Or maybe you weren't at much risk of, say, colon cancer in the first place.

Whereas studies about whole categories of foods (e.g. vegetables and fruits) typically involve larger groups of people for longer periods of time. So we can state with some confidence that eating lots of fruits and vegetables will increase your life expectancy. But how much of the benefit is coming from particular fruits or vegetables is less clear.

Some of the benefit of fruits and vegetables is probably coming from a displacement effect. The fruits and vegetables displace less healthy foods from the diet. Eat a lot of vegetables and therefore eat less white flour and other refined high glycemic index foods.

Share |      Randall Parker, 2007 November 23 02:22 PM  Aging Diet Resveratrol


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