title: Systemic availability and metabolism of colonic-derived short-chain fatty acids in healthy subjects: a stable isotope study.
abstract: The short-chain fatty acids (SCFAs) are bacterial metabolites produced during the colonic fermentation of undigested carbohydrates, such as dietary fibre and prebiotics, and can mediate the interaction between the diet, the microbiota and the host. We quantified the fraction of colonic administered SCFAs that could be recovered in the systemic circulation, the fraction that was excreted via the breath and urine, and the fraction that was used as a precursor for glucose, cholesterol and fatty acids. This information is essential for understanding the molecular mechanisms by which SCFAs beneficially affect physiological functions such as glucose and lipid metabolism and immune function.
  
  
  
  The short-chain fatty acids (SCFAs), acetate, propionate and butyrate, are bacterial metabolites that mediate the interaction between the diet, the microbiota and the host. In the present study, the systemic availability of SCFAs and their incorporation into biologically relevant molecules was quantified. Known amounts of13C-labelled acetate, propionate and butyrate were introduced in the colon of 12 healthy subjects using colon delivery capsules and plasma levels of13C-SCFAs13C-glucose,13C-cholesterol and13C-fatty acids were measured. The butyrate-producing capacity of the intestinal microbiota was also quantified. Systemic availability of colonic-administered acetate, propionate and butyrate was 36%, 9% and 2%, respectively. Conversion of acetate into butyrate (24%) was the most prevalent interconversion by the colonic microbiota and was not related to the butyrate-producing capacity in the faecal samples. Less than 1% of administered acetate was incorporated into cholesterol and <15% in fatty acids. On average, 6% of colonic propionate was incorporated into glucose. The SCFAs were mainly excreted via the lungs after oxidation to13CO2, whereas less than 0.05% of the SCFAs were excreted into urine. These results will allow future evaluation and quantification of SCFA production from13C-labelled fibres in the human colon by measurement of13C-labelled SCFA concentrations in blood.
authors: Translational Research in Gastrointestinal Disorders.|Leuven Food Science and Nutrition Research Centre.
authors: Eef
authors: E
authors: Boets
authors: Leuven Food Science and Nutrition Research Centre.|Center for Food and Microbial Technology.
authors: Sara V
authors: SV
authors: Gomand
authors: Translational Research in Gastrointestinal Disorders.|Leuven Food Science and Nutrition Research Centre.
authors: Lise
authors: L
authors: Deroover
authors: Stable Isotope Biochemistry Laboratory, Scottish Universities Environmental Research Centre, University of Glasgow, Glasgow, UK.
authors: Tom
authors: T
authors: Preston
authors: Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Merelbeke, Belgium.
authors: Karen
authors: K
authors: Vermeulen
authors: Translational Research in Gastrointestinal Disorders.|Group Health and Social Work, UC Leuven-Limburg, Leuven, Belgium.
authors: Vicky
authors: V
authors: De Preter
authors: Translational Research in Gastrointestinal Disorders.|Leuven Food Science and Nutrition Research Centre.
authors: Henrike M
authors: HM
authors: Hamer
authors: Drug Delivery and Disposition, KU Leuven, Leuven, Belgium.
authors: Guy
authors: G
authors: Van den Mooter
authors: Industrial Microbiology and Food Biotechnology, Vrije Universiteit Brussel, Brussel, Belgium.
authors: Luc
authors: L
authors: De Vuyst
authors: Leuven Food Science and Nutrition Research Centre.|Center for Food and Microbial Technology.
authors: Christophe M
authors: 0000-0002-1203-9063
authors: CM
authors: Courtin
authors: Drug Delivery and Disposition, KU Leuven, Leuven, Belgium.
authors: Pieter
authors: P
authors: Annaert
authors: Leuven Food Science and Nutrition Research Centre.|Center for Food and Microbial Technology.
authors: Jan A
authors: JA
authors: Delcour
authors: Translational Research in Gastrointestinal Disorders.|Leuven Food Science and Nutrition Research Centre.
authors: Kristin A
authors: KA
authors: Verbeke
mesh_terms: D000328:Adult; D002214:Capsules; D002247:Carbon Isotopes; D002784:Cholesterol / Q000378:metabolism; D003106:Colon / Q000378:metabolism* / Q000382:microbiology; D018592:Cross-Over Studies; D005232:Fatty Acids, Volatile / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D005260:Female; D000069196:Gastrointestinal Microbiome / Q000502:physiology; D005947:Glucose / Q000378:metabolism; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D055815:Young Adult
chemical_list: D002214:Capsules; D002247:Carbon Isotopes; D005232:Fatty Acids, Volatile; D002784:Cholesterol; D005947:Glucose
keywords: colonic fermentation; metabolism; short-chain fatty acids; stable isotopes; systemic exposure