Now Foods Grape Seed Anti-Oxidant 100 mg - 100 Vegetarian Capsules NOW Grape Seed Extract is a highly concentrated natural extract containing a minimum of 90% Polyphenols including OPC s (Oligomeric Proanthocyanidins) the beneficial antioxidant compounds found in Now Foods Grape Seeds. Now Foods Grape Seed Extract and OPC s have been the subject of numerous scientific studies demonstrating their efficacy in the support of cardiovascular health and immune system balance.