Grapes, grape juice and cancer

There are no single foods that by themselves can protect you against cancer. But there is evidence that the minerals, vitamins and phytochemicals found in plant foods could interact with each other to boost a person's individual cancer protection ability.

On the top of the list for protective foods are grapes and grape juice. Grapes are excellent sources of resveratrol, a type of natural phytochemical that belongs to a much larger group of phytochemicals called polyphenols.

The grape skin contains the most resveratrol, and the richer the color, the more there is. Red and purple grapes contain significantly more resveratrol than green grapes. Grape jam and raisins contain much smaller amounts of this phytochemical. Red wine also contains resveratrol.

Current cancer studies at the National Institutes of Health suggest that polyphenols in general and resveratrol, in particular, possess strong antioxidant and anti-inflammatory properties. In laboratory studies, resveratrol prevented the kind of damage identified to trigger the cancer process in cell, tissue and animal models. Specifically, resveratrol slowed the growth of cancer cells in the lymph, skin, liver, stomach and breast. However this has not yet been replicated in humans.

You can buy resveratrol supplements which contain extracts of the root of Polygonum cuspidatum, also known as Hu Zhang or kojo-kon. Red wine extracts and red grape extracts containing resveratrol are also available in the U.S. as dietary supplements. They contain anywhere from 10-50 mg of resveratrol.

My recommendation is always whole foods versus supplements. This is especially important with resveratrol because the effective doses for chronic disease prevention in humans are not known. In the lab, it has been found to inhibit human platelet agregation, so theoretically high intakes, through supplements, could potentially increase the risk of bleeding when taken with anticoagulant drugs, such as warfarin (Coumadin), clopidogrel (Plavix) and dipridamole (Persantine), non-steroidal anti-inflammatory drugs like aspirin, ibuprofen and others. Until more is known about the estrogenic activity of resveratrol in humans, women with a history of estrogen-sensitive cancers, such as breast, ovarian, and uterine cancers, should probably avoid resveratrol supplements.

Remember, no one food can protect you against cancer, but grapes offer a unique benefit to our health so probably should be added to our produce shopping lists.