Although previous studies have suggested a link between increased body mass index (BMI) and the risk of developing lower GI symptoms, the role obesity plays in the development of irritable bowel syndrome (IBS) is still not fully understood. A recent article published in The American Journal of Gastroenterology sought to investigate the link between visceral adipose tissue and the risk of developing IBS.

In this study, participants had undergone abdomen CT for a routine health screen from January 2012 to August 2013. The association between abdominal obesity and IBS was evaluated by measuring visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT),  VAT/SAT ratio, BMI and waist circumference in patients with IBS and controls without IBS.

Among all enrolled participants (336), the prevalence of IBS was 19.9%. The analysis showed that higher BMI or SAT is not associated with increased IBS risk; however, higher VAT area (odds ratio [OR]= 9.42), VAT/SAT ratio (OR= 10.15), and waist circumference (OR= 7.81) were independently associated with an increased risk. Visceral adiposity was linked to an increased risk of IBS only in the IBS-D group (diarrhea dominant IBS) and not the IBS-C (constipation dominant IBS) group.

The authors conclude that visceral abdominal obesity, not general obesity, is a significant independent risk factor of IBS, especially IBS-D.  This finding supports the theory that visceral adiposity increases pro-inflammatory cytokine release, which in turn may alter intestinal permeability, and cause chronic diarrhea in patients with IBS-D.