title: Relative bioavailability of the antioxidant flavonoid quercetin from various foods in man.
abstract: Quercetin is a strong antioxidant and a major dietary flavonoid. Epidemiological studies suggest that consumption of quercetin protects against cardiovascular disease, but its absorption in man is controversial. We fed nine subjects a single large dose of onions, which contain glucose conjugates of quercetin, apples, which contain both glucose and non-glucose quercetin glycosides, or pure quercetin-3-rutinoside, the major quercetin glycoside in tea. Plasma levels were then measured over 36 h. Bioavailability of quercetin from apples and of pure quercetin rutinoside was both 30% relative to onions. Peak levels were achieved less than 0.7 h after ingestion of onions, 2.5 h after apples and 9 h after the rutinoside. Half-lives of elimination were 28 h for onions and 23 h for apples. We conclude that conjugation with glucose enhances absorption from the small gut. Because of the long half-lives of elimination, repeated consumption of quercetin-containing foods will cause accumulation of quercetin in blood.
authors.affiliation: DLO-State Institute for Quality Control of Agricultural Products (RIKILT-DLO), Wageningen, The Netherlands. p.c.h.hollman@rikilt.dlo.nl
authors.forename: P C
authors.initials: PC
authors.lastname: Hollman
authors.forename: J M
authors.initials: JM
authors.lastname: van Trijp
authors.forename: M N
authors.initials: MN
authors.lastname: Buysman
authors.forename: M S
authors.initials: MS
authors.lastname: van der Gaag
authors.forename: M J
authors.initials: MJ
authors.lastname: Mengelers
authors.forename: J H
authors.initials: JH
authors.lastname: de Vries
authors.forename: M B
authors.initials: MB
authors.lastname: Katan
mesh_terms: D000328:Adult; D000975:Antioxidants / Q000032:analysis / Q000493:pharmacokinetics*; D001682:Biological Availability; D003296:Cooking; D004032:Diet; D005260:Female; D005527:Food, Fortified; D005638:Fruit; D006207:Half-Life; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D019697:Onions; D011794:Quercetin / Q000008:administration & dosage / Q000493:pharmacokinetics*
chemical_list: D000975:Antioxidants; D011794:Quercetin