Objectives: There are several studies considering obesity as the risk factor for various lower gastrointestinal symptoms. But the relationship between visceral abdominal obesity and the incidence of irritable bowel syndrome (IBS) is not studied yet. The aim of this study was to investigate the association between visceral adipose tissue (VAT) and the risk of IBS.
Methods: This is a case-control study comparing the VAT area between subjects with IBS (IBS group) and controls without IBS (non IBS group), who underwent abdomen computerized tomography (CT) for routine health checkup from January 2012 to August 2013 in a health promotion center. A telephone survey was retrospectively conducted to diagnose IBS by Rome III criteria. The association between IBS and abdominal obesity was evaluated by measuring VAT, subcutaneous adipose tissue (SAT), VAT/SAT ratio, body mass index (BMI) and waist circumference (WC).
Results: The prevalence of IBS was 19.9% (67/336) among all enrolled subjects. In the univariate analysis, VAT area, VAT/SAT ratio, waist circumference, the presence of reflux esophagitis and the ratio of females were significantly higher in the IBS group than in the non IBS group. However, a higher BMI or a higher SAT area is not associated with an increased risk of IBS. In the multivariate analysis, a higher VAT area (odds ratio (OR)=9.42, 95% confidence interval (CI): 2.90-30.64, highest tertile vs. lowest tertile, P=0.001), VAT/SAT ratio (OR=10.15, 95% CI: 3.05-33.58, highest tertile vs. lowest tertile, P=0.001) and waist circumference (OR=7.81, 95% CI: 2.13-28.66, highest tertile vs. lowest tertile, P=0.002) were independently associated with a risk of IBS. Only in the IBS-D group, not in the IBS-C, visceral adiposity was associated with an increased risk of IBS.
Conclusions: Visceral adiposity measured by VAT, VAT/SAT, and waist circumference is associated with an increased risk of IBS, especially of IBS-D. However, neither SAT nor BMI are associated with an increased risk of IBS.