Jarrow FORMULAS Green Tea 500 is water extracted and consists of 40% polyphenols including 30% catechins. Catechins are flavan monomers the building blocks of OPCs. OPCs OligoProanthoCyanidins are polymers (or chains)of flavans. Catechins are generally more bioavailable and more potent antioxidants than proanthocyanidins.Other products from HerbsPro