title: Fecal microbial metabolism of polyphenols and its effects on human gut microbiota.
abstract: We investigated the biotransformation of four common dietary polyphenols, rutin, quercetin, chlorogenic acid and caffeic acid, in an in vitro mixed culture model of human intestinal microbiota, to determine effects on human gut bacteria. All four compounds were biotransformed rapidly, disappearing from the medium within 0.5 h and later replaced by known phenolic acid breakdown products, at concentrations up to hundreds of micromolar, much higher than in no-polyphenol control experiments. Quantitative PCR was used to measure effects of the polyphenols on the balance between the major groups of intestinal bacteria that are known to influence gut health, i.e., Bifidobacterium spp., Bacteroidetes, and Firmicutes. Fermentation of polyphenols stimulated proliferation of bifidobacteria and decreased the ratio of Firmicutes to Bacteroidetes, relative to controls. Polyphenols also stimulated short chain fatty acid production by the bacteria. Pure bifidobacterial cultures were treated separately with either fermented media isolated from the incubations, the pure test polyphenols, or the biotransformation products detected in the fermentations. Growth stimulation was observed only with fermented polyphenol media and the pure biotransformation products. It appears that dietary polyphenols may have the ability to modify the gut microbial balance, but this effect is indirect, i.e., it is mediated by biotransformation products, rather than the original plant compounds.
authors.affiliation: The New Zealand Institute for Plant & Food Research Limited, Private Bag 3123, Waikato Mail Centre, Hamilton 3240, New Zealand. Electronic address: shanthi.parkar@plantandfood.co.nz.
authors.forename: Shanthi G
authors.initials: SG
authors.lastname: Parkar
authors.forename: Tania M
authors.initials: TM
authors.lastname: Trower
authors.forename: David E
authors.initials: DE
authors.lastname: Stevenson
mesh_terms: D001419:Bacteria / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D058448:Biota; D001711:Biotransformation; D003470:Culture Media / Q000737:chemistry; D005243:Feces / Q000382:microbiology; D041981:Gastrointestinal Tract / Q000382:microbiology*; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D008962:Models, Theoretical; D059808:Polyphenols / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D003470:Culture Media; D059808:Polyphenols
keywords: 3-(3-hydroxyphenyl)propionic acid; 3-(4-hydroxyphenyl)propionic acid; 3-hydroxylphenylacetic acid; 3OHPAA; 3OHPPA; 4OHPPA; Bifidobacterium longum; Fecal fermentation; Firmicutes:Bacteroidetes ratio; HPLC; MRS; RT-PCR; SCFA; Short chain fatty acid; WCA; Wilkins–Chalgren anaerobe; de Man Rogosa Sharpe; diOHPPA; dihydroxyphenylpropionic acid or hydrocaffeic acid; high performance liquid chromatography; polyphenol; real-time polymerase chain reaction; short chain fatty acids