Table 1.

Flavonoid subclasses and their naturally occurring forms.

Flavonoid Subclass	Food Source	Additional Naturally Occurring Forms
Anthocyanidins; e.g., cyanidin, delphinidin	Berries	Anthocyanidins may occur in methylated form, e.g., malvidin. All anthocyanidins conjugate with saccharide (sugar) groups to form anthocyanins *, e.g., chrysanthemin
Flavanols; e.g., catechin	Tea, cocoa	All flavanols are isomers, polymers or gallated conjugates of catechin, e.g., epicatechin *, epigallocatechin gallate (EGCG) *
Flavonols; e.g., kaempferol *, quercetin *	Fruits, vegetables	Flavonols may occur in methylated form, e.g., isorhamnetin * and/or conjugate with saccharides
Flavones; e.g., apigenin, luteolin	Cereals, herbs	Flavones conjugate with saccharides
Flavanones; e.g., naringenin	Citrus fruits	Flavanones may occur in methylated form e.g., hesperetin *, and/or conjugate with saccharides, e.g., hesperidin *, narirutin *
Isoflavones; e.g., daidzein, genistein	Soya beans, peanuts	Isoflavones may occur in methylated form and/or conjugate with saccharides

* Flavonoid compounds included in this review.