Subject: Gut microbiota
SCOPE: The stratification of individuals according to their gut microbiota metabotypes is crucial to understand the polyphenols health effects as reported for isoflavones and ellagitannins. To date, the existence of human gut microbiota metabotypes associated with proanthocyanidins (PAs) catabolism remains unclear. METHODS & RESULTS: Sixty-eight healthy volunteers (40 adolescents and 28 adults) consumed a mixture of walnuts, almonds and hazelnuts for 3 days, providing 163.65 ± 11.74 mg of PAs. Urine samples were analyzed by UPLC-ESI-QTOF. Twenty-one isomers of conjugated valerolactones and valeric acids were identified, which derived from 6 valerolactone and valeric acid precursors after analysis of hydrolysed urine. This combined approach allowed discriminating between the inter-individual variability related to phase-II enzymes polymorphisms and the metabolism of PAs by the gut microbiota. No associations of PAs metabolism with gender, age, BMI or ellagitannin metabotypes were found. Different quantitative excretion was observed after multivariate analysis but not true gut microbiota metabotypes associated with PAs catabolism. CONCLUSIONS: The metabolism of PAs does not reveal urinary metabolites consistent with distinctive gut microbiota metabotypes. The quantitative excretion of metabolites is inadequate to stratify individuals due to the strong influence of external factors (source, quantity and time of the last intake of PAs, etc.). This article is protected by copyright. All rights reserved.