Monomeric Flavanols are More Efficient Substrates for gut Microbiota Conversion to Hydroxyphenyl‐ γ‐Valerolactone Metabolites than Oligomeric Procyanidins: A Randomized, Placebo‐Controlled Human Intervention Trial

SCOPE: The majority of ingested flavanols reach the colon where they are catabolised by the microbiota to form derivatives of hydroxyphenyl-gamma-valerolactones (HGVLs). It is not known if the HGVLs are catabolic products of monomeric catechins, oligomeric procyanidins (PC), or both. Using data from a randomized, double-blind, placebo-controlled, crossover trial we estimated the relative contributions of catechins and PC to the bioavailable pool of HGVLs. METHODS AND RESULTS: Participants ingested an apple extract once daily for 28-d that delivered the following: (i) 70 mg catechins and 65 mg PC (Low dose EPC) (ii) 140 mg catechins and 130 mg PC (High dose EPC), (iii) 6 mg catechins and 130 mg PC (OPC) and (iv) a placebo control. Urine was collected over a 24-h period before and after treatments. The median urinary excretion of HGVL metabolites after ingestion of the high dose EPC was 10-fold higher than that excreted after ingestion of the OPC that provided an equivalent dose of PC. Approximately 22% of catechins were converted to HGVLs in contrast to PC for which there was limited conversion. CONCLUSION: Monomeric catechins are efficiently converted to gut microbiota-derived HGVLs that are absorbed and excreted in human urine, whereas oligomeric PC are much less efficiently converted. This article is protected by copyright. All rights reserved.