Urinary Clearance of Cranberry Flavonol Glycosides in Humans.

Cranberry is reported to have health benefits including prevention of urinary tract infections and other chronic diseases, due to the high content of polyphenols including flavonols and flavan-3-ols. The aim of this study was to determine the clearance of flavonol glycosides and flavan-3-ols and/or their metabolites in human urine. Ten healthy women volunteers ingested 240 ml cranberry juice containing flavonol glycosides. Urine samples were collected at 0, 90, 225 and 360 minutes post-ingestion. While flavan-3-ols were not detected, five flavonol glycosides common in cranberry were identified. Quercetin-3-galactoside, the most abundant cranberry flavonol, exhibited highest peak urine concentration (Cmax) of 1315 pg/mg creatinine, followed by quercetin-3-rhamnoside, quercetin-3-arabinoside, myricetin-3-arabinoside and myricetin-3-galactoside. Quercetin-3-arabinoside showed delayed clearance, Cmax at 237 min (Tmax), relative to other flavonols (90-151 min). Both aglycone and conjugated sugar moiety structure mediates the flavonol's bioavailability. Inter-individual variation for bioavailability and clearance is also apparent. Metabolites, e.g. glucoronides, were not detected.