This is a specially developed formula of Trans-Resveratrol that consists of several quality sources of this natural ingredient. Resveratrol contains two isomers, cis-resveratrol and trans-resveratrol. Trans-resveratrol is the active form. No benefits have been associated with cis-resveratrol. By combining the best extracts of grape skins, red wine and Japanese knotweed, Progressive Laboratories has created a well-rounded product to support the nutritional needs of healthy aging.* Resveratrol occurs naturally in plants along with other polyphenols such as quercetin. Quercetin may enhance resveratrol’s bioavailability.