Human bioavailability of phenolic compounds found in common beans: the use of high-resolution MS to evaluate inter-individual variability.

Abstract

Although common beans (Phaseolus vulgaris L.) are consumed worldwide, studies on the metabolic fate of phenolic compounds from common beans are still very scarce. The present work aimed to study the bioavailability of phenolic compounds in human plasma and urine, after acute consumption of a single meal of cooked common beans. Blood and urine of seven volunteers were collected before (0 h) and at different time points (1, 2, 4, 6 and 8 h for plasma and 0-2, 2-4, 4-6, 6-8 and 8-24 h for urine) after beans' intake. Ultra-high performance liquid chromatography-quadrupole-time of flight-MS (UPLC-Q-TOF-MS) was used for quantification. After beans' intake, 405 (sd 3) g, containing 188 mg of phenolic compounds (expressed as gallic acid equivalents), there was a significant increase (P < 0·05) in the plasma concentration of six metabolites and in the urinary excretion of eleven metabolites. After 1 h post-consumption, metabolites, such as kaempferol-3-O-glucuronide, showed a significant increase in plasma concentration, suggesting kaempferol's glucuronidation in the upper gastrointestinal tract. More than 50 % of the total amount of metabolites, such as 4-methylcatechol-O-sulphate and dihydrocaffeic acid-3-O-sulphate, were excreted after 8 h post-consumption, indicating colonic bacterial metabolism of the phenolic compounds. Partial least square-discriminant analysis models clearly showed clusters of metabolites, which contributed to extend the list of compounds related to cooked common beans' human intake at different time points and showed the human inter-individual variability in plasma concentration as well as in urinary excreted metabolites, after cooked common beans' intake.