Which catechin is the most abundant in green tea?

Epigallocatechin gallate is the most abundant catechin in green tea. Usually abbreviated EGCG, it is a polyphenol formed from epigallocatechin and gallic acid. Catechins are naturally occurring flavanols that contribute to tea’s bitterness, astringency, and some of its color and flavor.

Green tea retains relatively high levels of catechins because its leaves are heated soon after harvesting, limiting oxidation. In black-tea production, enzymes promote oxidation and convert much of the original catechin content into compounds such as theaflavins and thearubigins. That is why green tea is especially associated with EGCG, even though other teas contain it too.

The alternatives can cause confusion. Caffeine is a stimulant, not a catechin, while theanine is an amino acid associated with tea. Epicatechin is another catechin, but it is not the predominant one in green tea. EGCG is also widely studied in laboratory and human research, although supplement claims about health benefits should not be confused with established medical treatment.