A principal component of the tea extract is tea polyphenol compounds, and said tea polyphenol compounds include the tea catechin compounds represented by the general formula (I) given below and the theaflavin compounds represented by the general formula (II) given below, and also thearubigin: ##STR1## in which R1 is a hydrogen atom or a hydroxy group and R2 is a hydrogen atom or a 3,4,5-trihydroxy