The Relationship Between Symptoms, Body Mass Index, Gastrointestinal Transit and Stool Frequency in Patients with Irritable Bowel Syndrome

Background And Aims: Motility disturbances are involved in the pathophysiology of the irritable bowel syndrome (IBS). Population-based studies have shown an association between increasing body mass index (BMI) and different gastrointestinal (GI) symptoms. The aim of this prospective study was to characterize the relationships between symptoms in IBS, GI transit, as a measure of GI motility, and BMI.

Methods: We included 96 IBS patients in which 34 patients had diarrhea predominance (D-IBS), 16 had predominant constipation (C-IBS) and 46 had alternating bowel habits (A-IBS). All patients completed a GI symptom questionnaire and underwent a measurement of gastric emptying, small bowel residence and colonic transit. Transit values in 83 healthy individuals served as reference. BMI was calculated.

Results: At least one transit abnormality was found in 49 of 96 patients (51%). Increasing severity of urgency, loose stools and reflux were associated with higher BMI. Moreover, patients overweight had significantly faster colonic and rectosigmoid transit and higher stool frequency compared with normal weight patients. The symptom severities of pain/discomfort and bloating were associated with colonic transit abnormalities. In women, transit in the small bowel and colon was significantly slower in C-IBS compared with D-IBS.

Conclusion: GI transit is of relevance for the symptom pattern in patients with IBS. High BMI is associated with fast regional bowel transit and may therefore influence some stool-related symptoms in IBS.