Flavanol monomer-induced changes to the human faecal microflora

Abstract

We have investigated the bacterial-dependent metabolism of (2 )-epicatechin and (þ )-catechin using a pH-controlled, stirred, batch-culture fermentation system reflective of the distal region of the human large intestine. Incubation of (2)-epicatechin or (þ )-catechin (150 mg/l or 1000 mg/l) with faecal bacteria, led to the generation of 5-(3 0 ,4 0 -dihydroxyphenyl)-g-valerolactone, 5-phenyl-g-valerolactone and phenylpropionic acid. However, the formation of these metabolites from (þ )-catechin required its initial conversion to (þ )-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. (þ )-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 (2)-epicatechin was less profound, only significantly increasing the growth of the C. coccoides -Eubacterium rectale group. These potential prebiotic effects for both (þ )-catechin and (2 )-epicatechin were most notable at the lower concentration of 150 mg/l. As both (2)-epicatechin and (þ )-catechin were converted to the same metabolites, the more dramatic change in the growth of distinct microfloral populations produced by (þ )-catechin incubation may be linked to the bacterial conversion of (þ )-catechin to (þ)-epicatechin. Together these data suggest that the consumption of flavanol-rich foods may support gut health through their ability to exert prebiotic actions. Flavanols: Prebiotics: Faecal microflora: Large intestineRepresenting one of the most important lifestyle factors, diet can strongly influence the incidence and onset of CVD (1) , and thus a healthy diet is an essential factor for healthy ageing (2) . A number of dietary intervention studies in human subjects and animals, in particular those using Vitis vinifera (grape), Camellia sinensis (tea) and Theobroma cacao (cocoa) have demonstrated beneficial effects on vascular function (3 -5) . While such foods and beverages differ greatly in chemical composition and macro-and micronutrient content, they have in common that they are amongst the major dietary sources of flavanols. The in vivo effects of flavanols will be dependent on the absorption and metabolism of flavanols in the gastrointestinal tract. Studies have indicated that flavanols are subject to extensive metabolism by phase I and II enzymes to yield O-methylated, sulfated and glucuronidated forms during transfer from the small-intestinal lumen to the portal blood (6) . However, significant amounts of ingested (2 )-epicatechin, (þ)-catechin, and their structurally related oligomeric forms (procyanidins), escape absorption in the small intestine, instead rea...

Novel approaches for analysing gut microbes and dietary polyphenols: challenges and opportunities

“…For example, (+)-catechin significantly inhibited growth of Clostridium histolyticum, whereas growth of members of the Clostridium coccoides-Eubacterium rectale group and Escherichia coli was significantly enhanced and growth of Bifidobacterium and Lactobacillus spp. remained relatively unaffected (Tzounis et al, 2008). Moreover, two rat studies showed an impact of a polyphenol-rich diet on particular gut bacterial populations.…”

Effect of horse chestnut and inulin as single supplements or in combination on chemically induced colon cancer in rats

“…It was shown that several polyphenols, such as caffeic acid, catechin, epicatechin, coumaric acid, phloridzin, rutin, naringenin, daidzein, genistein and quercetin, inhibit the growth and adhesion of bacterial pathogens to human Caco-2 cells and enhance the proliferation and adhesion of probiotic bacteria L. rhamnosus (Parkar et al 2008). The consumption of flavonol-rich foods has been shown to modify the composition of the gut microbiota, exerting prebiotic-like effects (Tzonuis et al 2008). Tea phenolics have shown to inhibit the growth of Bacteroides spp., Clostridium spp.…”

Beneficios de los polifenoles contenidos en la cerveza sobre la microbiota intestinal

“…Cambiando el foco de atención a polifenoles concretos, más que en el alimento/bebida, en la literatura científica se encuentran más ejemplos: la quercetina tiene un efecto sobre el índice Firmicutes/Bacteroidetes relativo a la obesidad (19) ya que, junto a la rutina, estimula el crecimiento de Bacteroidetes, traducién-dose en un aumento de butirato (quercetina) y de propionato (rutina) (20); la (-)epicatequina y la (+)catequina influyen en el crecimiento de bacterias beneficiosas como las del grupo Clostridium Coccoides y Eubacterium Caccae, mientras que limitan el crecimiento de bacterias perjudiciales como C. Histolyticum (21). Todos estos polifenoles se encuentran en la cerveza, por lo que su potencialidad como modulador de la microbiota intestinal está fuertemente apoyada.…”