From the Manufacturer:
Green Tea has become a benchmark antioxidant based on its high concentrations of polyphenols, a powerful class of bioflavonoids that have been shown to greatly assist in the destruction of oxidation forming free radicals. Although it’s commonly used in teas, aromatherapy and tinctures, the highest concentrations can be found in capsule form. NOW Green Tea extract is standardized to 40% catechins to provide maximum benefits.