Flavanol monomer-induced changes to the human faecal microflora

Tzounis, X., Vulevic, J., Kuhnle, G. G. C. ORCID: https://orcid.org/0000-0002-8081-8931, George, T., Leonczak, J., Gibson, G. R. ORCID: https://orcid.org/0000-0002-0566-0476, Kwik-Uribe, C. and Spencer, J. P. E. ORCID: https://orcid.org/0000-0003-2931-7274 (2008) Flavanol monomer-induced changes to the human faecal microflora. British Journal of Nutrition, 99 (4). pp. 782-792. ISSN 0007-1145 doi: 10.1017/s0007114507853384

Abstract/Summary

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 (150mg/l or 1000mg/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.