Green tea is rich in a group of substances called catechin polyphenols. These include catechin, epicatechin, epicatechin gallate (ECG), and the most powerful of them: epigallocatechin gallate (EGCG), plus various pro-anthocyanidins. They are also known as flavonoids, and are one of the most powerful antioxidants. It also contains precious amino acids such as thianine or theanine. Thanks to its high content of antioxidants green tea is a powerful natural way of defending the harmful effects of free radicals and UV-induced oxidative stress and can delay the signs of ageing. Green tea can also support fat burning and enhance the metabolism.