Jarrow Formulas™ Green Tea 5:1 is water extracted and consists of 50% polyphenols, including 33% 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 an antioxidant than proanthocyanidins. This top quality green tea (Camellia sinesis), grown in Zhejiang, China, has been inspected by the Ministry of Agriculture.