title: Colonic content: effect of diet, meals, and defecation.
abstract: BACKGROUND
  The metabolic activity of colonic microbiota is influenced by diet; however, the relationship between metabolism and colonic content is not known. Our aim was to determine the effect of meals, defecation, and diet on colonic content.
  
  
  METHODS
  In 10 healthy subjects, two abdominal MRI scans were acquired during fasting, 1 week apart, and after 3 days on low- and high-residue diets, respectively. With each diet, daily fecal output and the number of daytime anal gas evacuations were measured. On the first study day, a second scan was acquired 4 hours after a test meal (n=6) or after 4 hours with nil ingestion (n=4). On the second study day, a scan was also acquired after a spontaneous bowel movement.
  
  
  RESULTS
  On the low-residue diet, daily fecal volume averaged 145 ± 15 mL; subjects passed 10.6 ± 1.6 daytime anal gas evacuations and, by the third day, non-gaseous colonic content was 479 ± 36 mL. The high-residue diet increased the three parameters to 16.5 ± 2.9 anal gas evacuations, 223 ± 19 mL fecal output, and 616 ± 55 mL non-gaseous colonic content (P<.05 vs low-residue diet for all). On the low-residue diet, non-gaseous content in the right colon had increased by 41 ± 11 mL, 4 hours after the test meal, whereas no significant change was observed after 4-hour fast (-15 ± 8 mL; P=.006 vs fed). Defecation significantly reduced the non-gaseous content in distal colonic segments.
  
  
  CONCLUSIONS
  Colonic content exhibits physiologic variations with an approximate 1/3 daily turnover produced by meals and defecation, superimposed over diet-related day-to-day variations.
authors.affiliation: Digestive System Research Unit, University Hospital Vall d'Hebron, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Universitat Autònoma de Barcelona, Bellaterra (Cerdanyola del Vallès), Spain.
authors.forename: R A
authors.initials: RA
authors.lastname: Bendezú
authors.affiliation: Digestive System Research Unit, University Hospital Vall d'Hebron, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Universitat Autònoma de Barcelona, Bellaterra (Cerdanyola del Vallès), Spain.
authors.forename: M
authors.initials: M
authors.lastname: Mego
authors.affiliation: Department of Computer Languages and System, Universidad Politécnica de Cataluña, Barcelona, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Monclus
authors.affiliation: Radiology Department, University Hospital Vall d'Hebron, Barcelona, Spain.
authors.forename: X
authors.initials: X
authors.lastname: Merino
authors.affiliation: Digestive System Research Unit, University Hospital Vall d'Hebron, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Universitat Autònoma de Barcelona, Bellaterra (Cerdanyola del Vallès), Spain.
authors.forename: A
authors.initials: A
authors.lastname: Accarino
authors.affiliation: Digestive System Research Unit, University Hospital Vall d'Hebron, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Universitat Autònoma de Barcelona, Bellaterra (Cerdanyola del Vallès), Spain.
authors.forename: J R
authors.initials: JR
authors.lastname: Malagelada
authors.affiliation: Department of Computer Languages and System, Universidad Politécnica de Cataluña, Barcelona, Spain.
authors.forename: I
authors.initials: I
authors.lastname: Navazo
authors.affiliation: Digestive System Research Unit, University Hospital Vall d'Hebron, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Universitat Autònoma de Barcelona, Bellaterra (Cerdanyola del Vallès), Spain.
authors.forename: F
authors.initials: F
authors.lastname: Azpiroz
mesh_terms: D000328:Adult; D003106:Colon / Q000000981:diagnostic imaging / Q000502:physiology*; D003672:Defecation / Q000502:physiology*; D004032:Diet / Q000379:methods; D004043:Dietary Fiber / Q000008:administration & dosage*; D005243:Feces; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D062407:Meals / Q000502:physiology*; D008875:Middle Aged
chemical_list: D004043:Dietary Fiber
keywords: colonic content; diet; fecal output; intestinal gas; meals