Effect of a Low FODMAP Diet on SIBO
Effect of a Low FODMAP Diet on SIBO
Bloating is the most common symptom associated with disorders of brain-gut interaction (i.e.,
 functional bowel disorders) such as irritable bowel syndrome, a disorder characterized by
 abdominal pain and altered bowel habits which affects up to 11% of world population. A common
 cause of bloating is small intestinal bacterial overgrowth (SIBO), a condition defined by
 excessive and/or abnormal type of bacteria in the small bowel. The potential role of SIBO for
 irritable bowel syndrome (IBS) was initially proposed by Pimentel et al. Using lactulose
 breath tests (LBTs), 78% of patients with IBS were also diagnosed with SIBO. After antibiotic
 therapy, 48% of patients no longer met the Rome criteria for IBS. A recent systematic review
 and meta-analysis concluded that the prevalence of SIBO is increased in IBS.

 Despite the clinical efficacy of LFD in improving symptoms of IBS-D, its mechanism of action
 is not clear. Recently, Zhou et al have shown FODMAPs induce colonic tight junction
 dysfunction and visceral hypersensitivity in rat models, both of which are reversible when
 rats were fed an LFD. They further showed that this effect of FODMAPs is mediated by
 microbial dysbiosis and elevated fecal lipopolysaccharide level. However, studies evaluating
 the effect of LFD on colonic permeability of humans are lacking. Studies have shown
 significant differences in intra-individual luminal and mucosal microbiome of patients with
 functional gastrointestinal disorders as well as an increase in Prevotella abundance in IBS
 patients with SIBO as compared with IBS patients without SIBO. Thus, the exact effect of
 FODMAP on intestinal permeability and mucosal microbiome in humans is not clear and needs
 further evaluation.
Inclusion Criteria:

 -  Aged 18-65 years at the time of screening

 -  Meet Rome IV criteria for functional bloating

 -  IBS-SSS score of at 176 (0-500)

 -  SIBO positive

 Exclusion Criteria:

 -  individuals already on a LFD or other dietary restriction such as gluten free diet
 within the past 6 months

 -  individuals with peanut, soy, or seafood allergies or insulin-dependent diabetes

 -  known history of celiac disease, inflammatory bowel disease or microscopic colitis

 -  prior small bowel or colonic surgery or cholecystectomy

 -  pregnant patients

 -  antibiotics, excluding topical, in the past 3 months