All teas from the plant camellia sinensis contain flavonoids. In fact one third of the weight of a tea leaf is comprised of flavonoids, which are released when the tea leaves come in contact with boiling water.
Brewing your tea releases about 300 mg of flavonoids per 250 mL serving. This makes tea a key dietary source of flavonoids. In comparison to other recommended sources, fruit juices run at about 3-50 mg flavonoids per serving. While tea is a naturally rich source of flavonoids, it is not a substitute for fruits or vegetables which provide a wide range of nutrients such as flavonoids and essential vitamins and minerals.