Relative bioavailability of the flavonoids quercetin, hesperetin and naringenin given simultaneously through diet

The bioavailability and urinary excretion of three dietary flavonoids, quercetin, hesperetin and naringenin, were investigated. Ten healthy men were asked to consume a 'juice mix' containing equal amounts of the three flavonoids, and their urine and plasma samples were collected. The resulting mean plasma area under the curve (AUC)(0-48 h) and C(max) values for quercetin and hesperetin were similar, whereas the AUC(0-48 h) of naringenin and, thus, the relative bioavailability were higher after consumption of the same dose. The study consolidates a significantly lower urinary excretion of quercetin (1.5+/-1%) compared with hesperetin (14.2+/-9.1%) and naringenin (22.6+/-11.5%) and shows that this is not due to a lower bioavailability of quercetin, but rather reflects different clearance mechanisms.