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Original article
Anal gas evacuation and colonic microbiota in patients with flatulence: effect of diet
  1. Chaysavanh Manichanh1,
  2. Anat Eck1,
  3. Encarna Varela1,
  4. Joaquim Roca2,
  5. José C Clemente3,
  6. Antonio González3,
  7. Dan Knights3,
  8. Rob Knight3,
  9. Sandra Estrella1,
  10. Carlos Hernandez1,
  11. Denis Guyonnet4,
  12. Anna Accarino1,
  13. Javier Santos1,
  14. Juan-R Malagelada1,
  15. Francisco Guarner1,
  16. Fernando Azpiroz1
  1. 1Digestive 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
  2. 2Molecular Biology Institute of Barcelona, Consejo Superior de Investigaciones Cientificas, Barcelona, Spain
  3. 3Department of Chemistry and Biochemistry, University of Colorado at Boulder, and Howard Hughes Medical Institute, Boulder, Colorado, USA
  4. 4Digestive Health Department, Danone Research, Palaiseau, France
  1. Correspondence to Professor Fernando Azpiroz, Digestive System Research Unit, Hospital General Vall d'Hebron, Barcelona 08035, Spain; azpiroz.fernando{at}


Objective To characterise the influence of diet on abdominal symptoms, anal gas evacuation, intestinal gas distribution and colonic microbiota in patients complaining of flatulence.

Design 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.

  • Colonic Bacteria
  • Colonic Fermentation
  • Colonic Microflora
  • Functional Bowel Disorder
  • Visceral Sensitivity

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 3.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:

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