Relative bioavailability of the antioxidant flavonoid quercetin from various foods in man.
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.
Hollman
P C
PC
DLO-State Institute for Quality Control of Agricultural Products (RIKILT-DLO), Wageningen, The Netherlands. p.c.h.hollman@rikilt.dlo.nl
van Trijp
J M
JM
Buysman
M N
MN
van der Gaag
M S
MS
Mengelers
M J
MJ
de Vries
J H
JH
Katan
M B
MB
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*
D000975:Antioxidants; D011794:Quercetin