Dietary fat increases quercetin bioavailability in obese men and postmenopausal women

Quercetin (Q) has poor bioavailability. Paradoxically, its intake is inversely related with cardiovascular disease (CVD) risk. We hypothesized that dietary fat would improve Q bioavailability in adults at risk for CVD. In a randomized, cross‐over design, obese men and postmenopausal women (n = 4M/5F; 55.9 ± 6.4 y; 30.8 ± 4.1 kg/m 2 ) ingested Q aglycone (1095 mg) on 3 occasions with a fat‐free (<0.5g), low‐fat (4 g), or high‐fat (15 g) meal. Plasma was obtained at timed intervals for 24 h to measure Q and its methylated metabolites isorhamnetin (ISO) and tamarixetin (TAM). Compared to the fat‐free trial, Q bioavailability increased by 32% (AUC 0–24 h ; P <0.05) during the high‐fat trial only. The high‐fat meal also increased maximum Q concentrations (C max ; 1.60 ± 0.88 μM) by 45%, but time to maximum concentration (T max ; 353 ± 105 min) and half‐life (t 1/2 ; 515 ± 144 min) were unaffected. ISO AUC 0–24 h increased by 19% and C max increased by 40% (0.24 ± 0.11 vs. 0.17 ± 0.06 μM) without affecting T max (486 ± 113 min) or t 1/2 (1154 ± 633 min). TAM AUC 0–24 h increased by 43% and C max by 46% (0.52 ± 0.29 vs. 0.36 ± 0.11 μM) without affecting T max (399 ± 110 min) or t 1/2 (299 ± 287 min). Thus, dietary fat improves Q bioavailability, and subsequent biotransformation, by increasing its absorption. Further work is warranted to define the optimal amount and type of fat to improve Q bioavailability. Support provided by the Donaghue Nutrition Research Program.