Pine Bark Extract contains proanthocyanidins, which are also called "OPCs" for oligomeric procyanidins or "PCOs" for procyanidolic oligomers. They are a class of nutrients belonging to the flavonoid family. Proanthocyanidins can be found in many plants, most notably pine bark and grape seed.

Proanthocyanidins have antioxidant activity and they play a role in the stabilization of collagen and maintenance of elastin—two critical proteins in connective tissue that support organs, joints, blood vessels, and muscle. They have been shown to strengthen capillaries in double-blind research using as little as 100 mg per day. In another double-blind trial, French researchers reported that women with chronic venous insufficiency had reduced symptoms using 150 mg per day. In another French double-blind trial, supplementation with 100 mg taken three times per day, resulted in benefits within four weeks. And taken in doses of 200 mg per day for five weeks, proanthocyanidins have improved visual performance in the dark in healthy people. Research has shown that PCO's have the ability to support the following functions and conditions:

• Chronic venous insufficiency
• Capillary fragility
• Retinopathy
• Pancreatic insufficiency
• Varicose Veins