Grape seeds are a rich source of flavonoid compounds called proanthocyanidins (also called "OPCs" for oligomeric proanthocyanidins or "PCOs" for procyanidolic oligomers). These compounds have powerful antioxidant properties, which can be beneficial for cells and tissues throughout the body. Although PCOs are found in a wide variety of plants, the best supplemental sources are extracts from grape seeds and the bark of the maritime pine (Pycnogenol. Grape seed extracts are commonly standardized for 92 to 95 percent proanthocyanidin content to ensure consistent antioxidant potency.
The benefits of PCOs were first brought to light in 1534, when French explorer Jacques Cartier led an expedition up the Saint Lawrence river. Trapped by ice and forced to subsist on rations of salted meat and biscuits, Cartier's men began to exhibit signs of scurvy, a severe vitamin C deficiency disease whose cause was unknown at the time. Cartier and his crew survived, thanks to the advice of a Native American who showed them how to make a tea from the bark and needles of pine trees. More than 400 years later, Jacques Masquelier, a professor at the University of Bordeaux, read of Cartier's experience and decided to investigate the nutritive properties of pine bark. He discovered that pine bark contains powerful antioxidant compounds (PCOs), and patented a method to extract them from pine bark in 1951, and from grape seeds in 1970. Since that time, both grape seed and pine bark extracts have become popular dietary supplements for improving the body's antioxidant defense mechanisms
The chief active components of grape seeds are proanthocyanidins (PCOs), which usually comprise 92 to 95 percent of grape seed extracts. Pine bark extracts usually contain 80 to 85 percent PCOs.
For daily antioxidant support, 50 mg of grape seed extract per day is suitable for most people, although people with special health concerns often take 150 to 300 mg per day. Grape seed extract is very well tolerated in this dosage range, with no known side effects.