Grape skins contain resveratrol, a powerful polyphenol. Polyphenols are compounds found in plants, which have been shown to benefit the human body. More specifically, resveratrol is part of the stilbenoid family. Stilbenoids are a natural compound produced by certain plants in response to injury. The purpose of stilbenoids is to protect the plant, similarly, resveratrol has been shown to protect the cardiovascular system.