Resveratrol is a polyphenolic compound found in grapes, red wine, purple grape juice, peanuts, and some berries. When taken orally, resveratrol appears to be well-absorbed by humans, but its bioavailability is relatively low because it is rapidly metabolized and eliminated. Scientists became interested in exploring potential health benefits of resveratrol when its presence was reported in red wine, leading to speculation that resveratrol might help explain the ''French Paradox.'' Moderate alcohol consumption has been consistently associated with 20-30% reductions in coronary heart disease risk, but it is not yet clear whether red wine polyphenols, such as resveratrol, confer any additional risk reduction. Although resveratrol can inhibit the growth of cancer cells in culture and in some animal models, it is not known whether high intakes of resveratrol can prevent cancer in humans. Resveratrol administration has increased the lifespans of yeast, worms, fruit flies, fish, and mice fed a high-calorie diet, but it is not known whether resveratrol will have similar effects in humans. At present, relatively little is known about the effects of resveratrol in humans. Resveratrol (trans-resveratrol) is a phytoalexin produced naturally by several plants when under attack by pathogens such as bacteria or fungi. Resveratrol has also been produced by chemical synthesis and is sold as a nutritional supplement derived primarily from Japanese knotweed. In mouse and rat experiments, anti-cancer, anti-inflammatory, blood-sugar-lowering and other beneficial cardiovascular effects of resveratrol have been reported. Most of these results have yet to be replicated in humans. In the only positive human trial, extremely high doses (3-5 g) of resveratrol in a proprietary formulation have been necessary to significantly lower blood sugar. Resveratrol is found in the skin of red grapes and is a constituent of red wine, but apparently not in sufficient amounts to explain the French paradox. Experiments have shown that resveratrol treatment extended the life of fruit flies, nematode worms and short living fish but it did not increase the life span of mice. In 1997, Jang reported that topical resveratrol applications prevented the skin cancer development in mice treated with a carcinogen. There have since been dozens of studies of the anti-cancer activity of resveratrol in animal models. No results of human clinical trials for cancer have been reported. However, clinical trials to investigate the effects on colon cancer and melanoma (skin cancer) are currently recruiting patients.