Trans-resveratrol, the active isomer of resveratrol, occurs naturally in red grapes, berries, and other plants. The body uses this form, but rapid liver and gut metabolism limits oral absorption. Supplement makers try to boost bioavailability using liposomal delivery or adding piperine from black pepper.
Cardiovascular health and healthy blood sugar levels are common reasons people take trans-resveratrol. Interest also extends to healthy aging because of its antioxidant and anti-inflammatory effects. The compound is fat-soluble, so taking it with a fat-containing meal may modestly enhance absorption.
Typical daily doses are 150 to 500 mg, often in enhanced formulations. High doses may cause mild digestive upset.