Quercetin glycosides have beneficial effects on human health, however, the bioavailability is usually low and is influenced by the sugar moieties of glycosides and other food ingredients. We examined the effects of nondigestible saccharides, fructooligosaccharides (FOS) and difructose anhydride III (DFAIII), on the bioavailability of a quercetin glycoside, which is a mixture of 1-8 D-glucose adducts for quercetin aglycone (Q3GM). The blood levels of quercetin and methylquercetin conjugates were significantly higher in rats fed AIN93G-based test diets, including 1％ Q3GM with FOS or DFAIII (1.5％ and 3％) when compared with rats fed a Q3GM diet without nondigestible saccharides, on day 7 at 10:00 and 17:00 h. The blood levels of quercetin and methylquercetin conjugates tended to increase furthermore on day 13 in rats fed Q3GM diets with the oligosaccharides. Fecal excretion of quercetin and methylquercetin was also increased by FOS and DFAIII. Our results show that FOS and DFAIII promote the bioavailability of Q3GM; suppression of intestinal degradation of quercetin aglycone may party contribute to the promotive effects.

Key words: Quercetin glucoside, nondigestible saccharides, bioavailability, fecal excretion, rats