Chronic ingestion of apple pectin can enhance the absorption of quercetin.

The effect of apple pectin (AP) on quercetin and rutin bioavailability was investigated. Rats received a basal (control) or AP-containing diet for 6 weeks followed by orally administered quercetin or rutin. With quercetin administration, the maximum concentration and area under the curve of concentration−time from 0 to 24 h for the sum of quercetin metabolites in the plasma were significantly higher in AP-fed rats than in the control group. However, AP did not significantly affect rutin bioavailability. The crypt depth of the jejunum and ileum and the villus thickness of the ileum of AP-fed rats were significantly greater than those of control rats. These results demonstrate that chronic AP ingestion enhances intestinal absorption of quercetin. This increase in quercetin absorption might be attributed to alteration of the absorptive capacity of the small intestine through AP-induced improvement of its morphological and physiological properties.