Oligosaccharide promotes bioavailability of a water-soluble flavonoid glycoside, alpha G-rutin, in rats.

This study examined the effects of a nondigestible saccharide, difructose anhydride (DFA) III, and fructooligosaccharides (FOS) on the intestinal absorption and metabolism of alpha G-rutin, a quercetin glycoside in rats during a 2 week feeding period with diets containing 1% alpha G-rutin with or without 1.5 or 3% DFAIII and FOS. Blood concentrations and urinary excretion of quercetin derivatives were largely and dose-dependently increased during the test period with feeding DFA III and FOS. The amounts of quercetin derivatives in the cecal contents and feces were also much higher in both saccharide groups than in the control group. The degradation rate of aglycone, estimated by differences between ingestion and sum of fecal and urinary excretion, were suppressed in the both saccharide groups. Cecal fermentation was dose-dependently modified by the oligosaccharides. It was concluded that suppression of degrading quercetin aglycone in the large intestine has a major role for increasing alpha G-rutin bioavailability by DFA III and FOS feedings.