Grape Seed Extract naturally contains polyphenols known as oligomeric proanthocyanidins (OPCs). These active ingredients also exist in many plants and herbs such as green tea, bilberry and cranberry, and are important to healthful traditions around the world. In addition to begin cardio supportive, proanthocyanidin compounds possess antioxidant properties that help fight cell-damaging free radicals which can cause oxidative stress in the body, and in turn contribute to premature aging of cells.