Early termination due to lack of funds, staffing

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

SIBO positive participants who undergo 3 weeks of low FODMAP diet

2 years

Early termination leading to small numbers of subjects analyzed