Quercetin-3-glucoside bioavailability

Until recently, the extent of absorption and bioavailability of flavonoids was somewhat unclear. Studies with ileostomy patients have shown that humans can absorb significant amounts of quercetin and that glycosides can be absorbed from the small intestine. Absorption of quercetin glucosides was... 

M.R. Olthof, RC.H. Hollman, T.B. Vree and M.B. Katan, Bioavailabilities of quercetin-3-glu-coside and quercetin-4 -glucoside do not differ in humans. J. Nutrition 130 (2000) 1200-1203. 

The bioavailibility of quercetin-glycosides from onions, containing mainly quercetin-p-glucosides, was superior to that of various quercetin glycosides from apples (containing a mixture of quercetin-(3-galactosides and P-xylosides) and of pure quercetin-3-mtinoside (major species in tea). The possible matrix effect of the foods remains unclear. 

---