Tuesday, November 20, 2012
Resveratrol, wine, and cancer: an update
A recent study on the effects of resveratrol on prostate cancer highlights one of the tantalizing aspects of this red wine antioxidant: a long list of potential anti-cancer properties. It must be pointed out however that nearly all of the evidence for this comes from laboratory research, and though there are some clinical trials in progress it is premature to claim anti-cancer benefits for resveratrol supplements. But if any of it pans out it could lead to significant breakthroughs.
One of the things that make resveratrol so intriguing as an anti-cancer agent is that it not only suppresses cancer cell growth but seems to protect normal cells from the toxic effects of cancer treatment. Radiation treatment is a particularly troublesome therapy because of lasting effects on healthy cells in the treatment zone. But several lines of evidence suggest that resveratrol may pull off the ultimate hat trick: protecting the healthy cells while sensitizing cancerous cells to radiation.
This most recent study evaluated resveratrol as a ‘radiosensitizing” agent on a “radioresistant” clone of prostate cancer cells in culture. (Again, not an animal study or human clinical trial.) This confirms findings of earlier studies on prostate cancer, but other tumor lines exhibit a similar response to resveratrol. One intriguing example is glioblastoma, a particularly aggressive form of brain cancer. [reference] Melanoma cells may do likewise [reference] as do some types of lung cancer [reference].
Clinical evidence however points to a role for wine consumption. In a large series from Italy, patients undergoing radiation treatment for breast cancer had less irritation of the skin (called radiodermatitis) if they consumed red wine regularly. What is notable about this is that there isn’t enough resveratrol in wine to explain the effect. This is in fact the central dilemma about resveratrol as a candidate for all the healthy things that red wine does: lab studies show a plausible cause-effect explanation for observed inverse correlations between wine and disease, yet the amounts required to produce the effect are far more than what is available by consuming wine.
So what conclusion can we draw from this? First, much work needs to be done in the laboratory and the clinic before we can say definitively that resveratrol (or a derivative) is a useful adjunct to cancer treatment. Wine consumption generally correlates with reduced risk of cancer, in a J-shaped curve with the maximum benefit at moderate levels of consumption and increased risk with heavy consumption. It just doesn’t appear that this has much to do with resveratrol.