Among this selection you will discover a range of green teas whose reputation is second to none. Research has shown several positive effects on health and the prevention of certain types of cancers. Catechin is an antioxidant that strengthens the immune system and fights cholesterol. The main catechin in green tea is called EGCG (epigallocatechin gallate). EGCG is considered one of the major contributors to positive health effects . Japanese green teas are said to contain more than other Chinese or other green teas.