Repeated dosing and BMI influence plasma polyphenol response in humans

Abstract

Repeated dosing of grape polyphenols has been found to affect bioavailability and metabolism of catechin (C) and epicatechin (EC) in rats. In addition, obesity may influence intestinal function and xenobiotic metabolism, which could alter polyphenol bioavailability. To assess the impact of exposure and obesity on polyphenol bioavailability in humans, a pilot 11 day intervention was conducted with 12 adults with either normal BMI (23.5±0.7) or high BMI (30.6±0.6). Volunteers consumed 250 mg resveratrol, 900 mg grape seed extract, and 20 oz. Concord grape juice daily for 11 d. On d1 and d11, treatment was consumed after a 12h fast, then serial blood samples were collected for 6h. Plasma was extracted, and deconjugated C, EC, resveratrol (R), and quercetin (Q) were measured by LC‐MS/MS. Plasma AUCs were greater for C, EC, and Q on d11 compared to d1 for low BMI (P<0.039) but not high BMI individuals. Further, AUCs were greater for EC and R for low BMI compared to high BMI individuals (P<0.041), with a similar trend for C (p=0.065), on d11 but not d1. These results suggest that that repeated exposure and obesity likely influences polyphenol bioavailability in humans. Supported by the USDA and NCCAM.