Polyphenols from Alcoholic Apple Cider Are Absorbed, Metabolized and Excreted by Humans

Open Access
Publisher Website
Google Scholar
Abstract
We determined the uptake and excretion of low doses of polyphenols in six subjects who each consumed 1.1 L of an alcoholic cider beverage. Over a 24-h period, no phloretin was detected in plasma (detection limit = 0.036 μmol/L), but 21 ± 5% of the dose (4.8 mg) was excreted in the urine. In contrast, from a low dose of 1.6-mg quercetin equivalents, no quercetin was found in urine or plasma, but 3′-methyl quercetin was detected in plasma [Cmax (maximum concentration) = 0.14 ± 0.19 μmol/L; range: 0 to 0.44 μmol/L]. No flavanol monomers (dose of free (+)-catechin and (−)-epicatechin = 3.5 mg) were detected in urine or plasma (detection limit: 0.01 μmol/L). Caffeic acid (total dose including esters = 11 mg) was detected only in plasma within 2 h, with Cmax = 0.43 ± 0.3 μmol/L (range: 0.18 to 0.84 μmol/L). An almost 3-fold increase in hippuric acid was detected in 24-h urine (74 ± 29 μmol/L; range: 38–116 μmol/L), compared with a prestudy value of 19 ± 9 μmol/L. These data show that polyphenols are taken up from cider, that phloretin is excreted in the urine and suggest that low doses of quercetin are extensively methylated in humans.