The low FODMAP diet improves gastrointestinal symptoms in patients with irritable bowel syndrome: a prospective study

Int J Clin Pract. 2013 Sep;67(9):895-903. doi: 10.1111/ijcp.12128. Epub 2013 May 23.


Background and aim: Current treatment for irritable bowel syndrome (IBS) is suboptimal. Fermentable oligo-, di-, mono-saccharides and polyols (FODMAPs) may trigger gastrointestinal symptoms in IBS patients. Our aim was to determine whether a low FODMAP diet improves symptoms in IBS patients.

Methods: Irritable bowel syndrome patients, who had performed hydrogen/methane breath testing for fructose and lactose malabsorption and had received dietary advice regarding the low FODMAP diet, were included. The effect of low FODMAP diet was prospectively evaluated using a symptom questionnaire. Furthermore, questions about adherence and satisfaction with symptom improvement, dietary advice and diet were assessed.

Results: Ninety patients with a mean follow up of 15.7 months were studied. Most symptoms including abdominal pain, bloating, flatulence and diarrhoea significantly improved (p < 0.001 for all). 75.6%, 37.8% and 13.3% of patients had fructose, lactose malabsorption or small intestinal bacterial overgrowth respectively. Fructose malabsorption was significantly associated with symptom improvement (abdominal pain odds ratio (OR) 7.09 [95% confidence interval (CI) 2.01-25.0], bloating OR 8.71 (95% CI 2.76-27.5), flatulence OR 7.64 (95% CI 2.53-23.0) and diarrhoea OR 3.39 (95% CI 1.17-9.78), p < 0.029 for all). Most patients (75.6%) were adherent to the diet, which was associated with symptom improvement (abdominal pain, bloating, flatulence and diarrhoea all significantly associated with adherence, r > 0.27, p < 0.011). Most patients (72.1%) were satisfied with their symptoms.

Conclusions: The low FODMAP diet shows efficacy for IBS patients. The current strategy of breath testing and dietary advice provides a good basis to understand and adhere to the diet.

Publication types

  • Evaluation Study
  • Observational Study

MeSH terms

  • Abdominal Pain / diet therapy
  • Abdominal Pain / etiology
  • Breath Tests
  • Diarrhea / diet therapy
  • Diarrhea / etiology
  • Female
  • Flatulence / diet therapy
  • Flatulence / etiology
  • Fructose / pharmacokinetics
  • Fructose Intolerance / complications
  • Fructose Intolerance / diet therapy
  • Humans
  • Irritable Bowel Syndrome / diet therapy*
  • Irritable Bowel Syndrome / etiology
  • Lactose / pharmacokinetics
  • Lactose Intolerance / complications
  • Lactose Intolerance / diet therapy
  • Malabsorption Syndromes / complications
  • Malabsorption Syndromes / diet therapy*
  • Male
  • Middle Aged
  • Patient Compliance
  • Patient Satisfaction
  • Prospective Studies
  • Treatment Outcome


  • Fructose
  • Lactose