Flavonoids på Linus Pauling Institute - Micronutrient Information Center: "In general, the bioavailability of flavonoids is low due to limited absorption, extensive metabolism, and rapid excretion. Isoflavones are thought to be the most bioavailable of all flavonoid subclasses, while anthocyanins and galloylated catechins are very poorly absorbed." och "... the relative contribution of dietary flavonoids to plasma and tissue antioxidant function in vivo is likely to be very small or negligible."