Vascular Health Healthy Immune Response NOW Grape Seed Extract is a highly concentrated extract with a minimum of 90% polyphenols including oligomeric proanthocyanidins (OPCs) which are the potent water-soluble free radical scavenging compounds found in grape seeds. A growing body of research indicates that grape seed OPCs may help to support the health of vascular bone kidney brain and other tissues by supporting a healthy balanced immune response to oxidative and metabolic stress.