Resveratrol is a phytoalexin prouced 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. A number of beneficial health effects, such as anti-cancer, antiviral, neuroprotective, anti-aging, and anti-inflammatory effects, have been reported, but all of these studies are "in-vitro" (test tube) or in yeast, worms, fruit flies, fish, mice, and rats. Resveratrol is found in the skin of red grapes and is a constituent of red wine but, based on extrapolation from animal trials, apparently not in sufficient amounts to explain the "French paradox" that the incidence of coronary heart disease is relatively low in southern France despite high dietary intake of saturated fats.