Oligomeric proanthocyanidins (OPCs) are bioflavonoids (complex organic plant compounds) found in fruits, vegetables and certain tree barks that provide nutritional benefits to the human body. 

Studies have shown OPCs to be more powerful than vitamin C and vitamin E in neutralizing free radicals. Ixonix OPC-3 contains Pycnogenol^®, a natural plant extract from the bark of the French maritime pine tree and the most researched bioflavonoid.