Bioavailability of quercetin in pigs is influenced by the dietary fat content.

The flavonol quercetin is one of the most prevalent flavonoids found in edible plants. In this study, the influence of dietary fat on oral bioavailability of quercetin was investigated. Quercetin (30 micromol/kg body weight) was administered either as the lipophilic aglycone or as the more hydrophilic quercetin-3-O-glucoside in test meals differing in fat content (3, 17, or 32 g fat/100 g diet) to growing pigs. Blood samples were drawn repeatedly over a 24-h period and analyzed by HPLC. The main metabolite found in plasma was always conjugated quercetin. Quercetin bioavailability from each diet was always higher from the glucoside than from the aglycone. Irrespective of the chemical form applied, the bioavailability of quercetin was higher in the 17% fat diet compared with the 3% fat diet (P < 0.05). No further effect on bioavailability was observed when the flavonols were administered with diets containing 32% fat. The elimination of quercetin was significantly delayed after its application with fat-enriched diets (P < 0.05). Thus, in addition to the chemical form of the flavonol, the fat content of the diet influences oral bioavailability of quercetin.