The substance, which belongs to the phenols (polyphenols), was first isolated and identified in 1963 in knotweed plants (Polygonum cuspidatum). It is an antioxidant (oxidation inhibitor) and is present in plants and plant foods, especially in peanuts, raspberries, mulberries and also grapes. In the vine, resveratrol is formed in the leaves and skins of vines affected by downy mildew or botrytis, as well as under stress conditions such as UV light as a defensive reaction. It is a natural fungicide, so to speak. Such substances are also called phytoalexins. The resveratrol content in grapes or wines from cool and humid areas is much higher than in dry and warm areas. It is particularly present in the skins of dark grapes in more than five times the amount of light-coloured ones.
Resveratrol in wine can have a positive, health-promoting effect by preventing platelets from clumping together. The phenomenon was discovered in the USA in the 1980s and quickly became known worldwide under the catchword French paradox. In the meantime, in vitro studies have provided evidence of a possible efficacy against cancer cells. Resveratrol kills them by inhibiting a protein that is important for the survival of cancer cells. Other studies have shown positive effects on autoimmune deficiencies, arteriosclerosis, arthritis and heart disease. Most recently, scientists at the University of Wisconsin found in laboratory experiments that age-related changes in heart function can be attenuated, thereby slowing down the aging process. The required amount of resveratrol is already achieved with a daily glass of red wine. See also under anthocyanins.