High Quality Content by WIKIPEDIA articles! 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.