Simultaneous ingestion of apple pectin enhances the absorption and antioxidant activity of quercetin in rats

The enhanced bioavailability of quercetin (Qr), which has low absorption, may have beneficial effects on human health. This study aimed to elucidate the effects of simultaneous pectin ingestion on the absorption and antioxidant activity of Qr. Qr concentrations in the plasma and urine of rats fed Qr + cellulose or Qr + pectin diets were determined, and thiobarbituric acid reactive substances (TBARS) in oxidized low-density lipoprotein (LDL) were measured. The concentrations of Qr and its metabolites in the plasma and urine increased one day after feeding the Qr + pectin diet compared with the Qr + cellulose diet. The elevation of TBARS was suppressed in rats fed the Qr + pectin diet. Qr concentrations in the plasma and LDL increased in a dose-dependent manner with pectin. Qr levels in plasma and LDL were negatively correlated with TBARS levels in LDL. The simultaneous ingestion of pectin has been suggested to immediately enhance the absorption and antioxidant activity of Qr.