Total ¯avonol and ¯avone contents of foods have been determined with validated state-ofthe-art methods. Quercetin dominates, and ¯avonol levels found in vegetables and fruits are below 10 mg kg À1 . However, high concentrations are found in onions (300 mg kg À1 ), kale (450 mg kg À1 ), broccoli (100 mg kg À1 ), beans (50 mg kg À1 ), apples (50 mg kg À1 ), blackcurrants (40 mg kg À1 ), and tea (30 mg l À1 ). The dietary intake of ¯avonols varies 10-fold between countries (6±60 mg day À1 ). Flavones are of minor importance in the diet. Tea, wine and fruits are the most important sources of ¯avanols, but there are gaps in our knowledge on ¯avanol levels of many foods. The absorption of dietary quercetin glycosides in humans ranges from 20 to 50%. The sugar moiety is an important determinant of the bioavailability of ¯avonols. The presence of a glucose moiety signi®cantly enhances absorption. The extent of absorption of ¯avanols in humans seems similar to that of ¯avonols but has been little studied. Flavonols and ¯avanols are extensively metabolised, as only 1±2% of them are excreted with an intact ¯avonoid backbone. Hepatic biotransformations include glucuronidation and sulphatation of the phenolic hydroxyls and O-methylation of catechol groups. Bacteria of the colon cleave the C-ring of the ¯avonoid nucleus to phenolic acids which are subsequently absorbed. Apart from conjugates, virtually no metabolites have been characterised in humans. Absorption of ¯avanols is rather fast, with times to reach peak values between 0.5 and 4 h. Flavanols are rapidly excreted, with elimination halflives of 1±6 h. Quercetin glycosides show rapid to slow absorption; peak values are reached between `0.5 and 9 h. The type of glycoside determines the rate of absorption. Excretion of quercetin glycosides is slow: elimination half-lives are 24 h, independent of the type of glycoside. Analytical data for ¯avanols in foods are needed. Tea, as an important dietary source, has to be studied. Research on the bioavailability of ¯avonols and ¯avanols has to be expanded. Attention is needed for the identi®cation and quanti®cation of their metabolites in body ¯uids.