title: Anal gas evacuation and colonic microbiota in patients with flatulence: effect of diet.
abstract: OBJECTIVE
  To characterise the influence of diet on abdominal symptoms, anal gas evacuation, intestinal gas distribution and colonic microbiota in patients complaining of flatulence.
  
  
  METHODS
  Patients complaining of flatulence (n=30) and healthy subjects (n=20) were instructed to follow their usual diet for 3 days (basal phase) and to consume a high-flatulogenic diet for another 3 days (challenge phase).
  
  
  RESULTS
  During basal phase, patients recorded more abdominal symptoms than healthy subjects in daily questionnaires (5.8±0.3 vs 0.4±0.2 mean discomfort/pain score, respectively; p=<0.0001) and more gas evacuations by an event marker (21.9±2.8 vs 7.4±1.0 daytime evacuations, respectively; p=0.0001), without differences in the volume of gas evacuated after a standard meal (262±22 and 265±25 mL, respectively). On flatulogenic diet, both groups recorded more abdominal symptoms (7.9±0.3 and 2.8±0.4 discomfort/pain, respectively), number of gas evacuations (44.4±5.3 and 21.7±2.9 daytime evacuations, respectively) and had more gas production (656±52 and 673±78 mL, respectively; p<0.05 vs basal diet for all). When challenged with flatulogenic diet, patients' microbiota developed instability in composition, exhibiting variations in the main phyla and reduction of microbial diversity, whereas healthy subjects' microbiota were stable. Taxa from Bacteroides fragilis or Bilophila wadsworthia correlated with number of gas evacuations or volume of gas evacuated, respectively.
  
  
  CONCLUSIONS
  Patients complaining of flatulence have a poor tolerance of intestinal gas, which is associated with instability of the microbial ecosystem.
authors.affiliation: Digestive System Research Unit, Departament de Medicina, University Hospital Vall d'Hebron, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Universitat Autònoma de Barcelona, , Barcelona, Spain.
authors.forename: Chaysavanh
authors.initials: C
authors.lastname: Manichanh
authors.forename: Anat
authors.initials: A
authors.lastname: Eck
authors.forename: Encarna
authors.initials: E
authors.lastname: Varela
authors.forename: Joaquim
authors.initials: J
authors.lastname: Roca
authors.forename: José C
authors.initials: JC
authors.lastname: Clemente
authors.forename: Antonio
authors.initials: A
authors.lastname: González
authors.forename: Dan
authors.initials: D
authors.lastname: Knights
authors.forename: Rob
authors.initials: R
authors.lastname: Knight
authors.forename: Sandra
authors.initials: S
authors.lastname: Estrella
authors.forename: Carlos
authors.initials: C
authors.lastname: Hernandez
authors.forename: Denis
authors.initials: D
authors.lastname: Guyonnet
authors.forename: Anna
authors.initials: A
authors.lastname: Accarino
authors.forename: Javier
authors.initials: J
authors.lastname: Santos
authors.forename: Juan-R
authors.initials: JR
authors.lastname: Malagelada
authors.forename: Francisco
authors.initials: F
authors.lastname: Guarner
authors.forename: Fernando
authors.initials: F
authors.lastname: Azpiroz
mesh_terms: D015746:Abdominal Pain / Q000175:diagnosis / Q000209:etiology; D000328:Adult; D000368:Aged; D044822:Biodiversity; D016022:Case-Control Studies; D003106:Colon / Q000382:microbiology*; D004269:DNA, Bacterial / Q000032:analysis; D004032:Diet / Q000009:adverse effects*; D005414:Flatulence / Q000150:complications / Q000175:diagnosis / Q000382:microbiology* / Q000503:physiopathology; D006801:Humans; D064307:Microbiota / Q000235:genetics; D008875:Middle Aged; D010147:Pain Measurement; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011446:Prospective Studies; D017422:Sequence Analysis, DNA; D011795:Surveys and Questionnaires; D014057:Tomography, X-Ray Computed
chemical_list: D004269:DNA, Bacterial
keywords: Colonic Bacteria; Colonic Fermentation; Colonic Microflora; Functional Bowel Disorder; Visceral Sensitivity