title: Flavanol monomer-induced changes to the human faecal microflora.
abstract: We have investigated the bacterial-dependent metabolism of ( - )-epicatechin and (+)-catechin using a pH-controlled, stirred, batch-culture fermentation system reflective of the distal region of the human large intestine. Incubation of ( - )-epicatechin or (+)-catechin (150 mg/l or 1000 mg/l) with faecal bacteria, led to the generation of 5-(3',4'-dihydroxyphenyl)-gamma-valerolactone, 5-phenyl-gamma-valerolactone and phenylpropionic acid. However, the formation of these metabolites from (+)-catechin required its initial conversion to (+)-epicatechin. The metabolism of both flavanols occurred in the presence of favourable carbon sources, notably sucrose and the prebiotic fructo-oligosaccharides, indicating that bacterial utilisation of flavanols also occurs when preferential energy sources are available. (+)-Catechin incubation affected the growth of select microflora, resulting in a statistically significant increase in the growth of the Clostridium coccoides-Eubacterium rectale group, Bifidobacterium spp. and Escherichia coli, as well as a significant inhibitory effect on the growth of the C. histolyticum group. In contrast, the effect of ( - )-epicatechin was less profound, only significantly increasing the growth of the C. coccoides-Eubacterium rectale group. These potential prebiotic effects for both (+)-catechin and ( - )-epicatechin were most notable at the lower concentration of 150 mg/l. As both ( - )-epicatechin and (+)-catechin were converted to the same metabolites, the more dramatic change in the growth of distinct microfloral populations produced by (+)-catechin incubation may be linked to the bacterial conversion of (+)-catechin to (+)-epicatechin. Together these data suggest that the consumption of flavanol-rich foods may support gut health through their ability to exert prebiotic actions.
authors.affiliation: Molecular Nutrition Group, School of Chemistry, Food and Pharmacy, University of Reading, Reading RG2 6AP, UK.
authors.forename: Xenofon
authors.initials: X
authors.lastname: Tzounis
authors.forename: Jelena
authors.initials: J
authors.lastname: Vulevic
authors.forename: Gunter G C
authors.initials: GG
authors.lastname: Kuhnle
authors.forename: Trevor
authors.initials: T
authors.lastname: George
authors.forename: Jadwiga
authors.initials: J
authors.lastname: Leonczak
authors.forename: Glenn R
authors.initials: GR
authors.lastname: Gibson
authors.forename: Catherine
authors.initials: C
authors.lastname: Kwik-Uribe
authors.forename: Jeremy P E
authors.initials: JP
authors.lastname: Spencer
mesh_terms: D000975:Antioxidants / Q000378:metabolism / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects / Q000378:metabolism*; D001431:Bacteriological Techniques; D001644:Bifidobacterium / Q000254:growth & development; D002392:Catechin / Q000378:metabolism / Q000494:pharmacology; D003013:Clostridium / Q000254:growth & development; D004926:Escherichia coli / Q000254:growth & development; D005051:Eubacterium / Q000254:growth & development; D005243:Feces / Q000382:microbiology*; D005285:Fermentation; D005419:Flavonoids / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D007420:Intestine, Large / Q000378:metabolism / Q000382:microbiology
chemical_list: D000975:Antioxidants; D005419:Flavonoids; D002392:Catechin