IBS Management: The Complex Role of Dietary Fiber

A novel trial underpins the differential impact that dietary fiber can have on IBS symptoms and the gut microbiota.

Recent research has underscored the complex influence of varied dietary fiber types on irritable bowel syndrome (IBS), particularly noting their effects on gut transit time and microbiota, notwithstanding certain side effects, such as colonic gas production.

The investigation, presented by Jose Maria Remes-Troche, MD, at DDW 2023, was a double-blind, placebo-controlled clinical trial conducted across Mexico and the United Kingdom. It evaluated the effect of co-administering distinct types of dietary fibers on IBS patients. Participants were given either a placebo, a combined dose of extracted fibers (inulin and psyllium), or native fibers (nopal) twice daily over 8 weeks. The trial’s main objective was to measure the impact of these interventions on the patients’ gut microbiota and IBS symptoms. Secondary objectives included evaluating stool consistency, gut transit times, and microbial metabolites.

Included were 133 patients who were randomly assigned to receive inulin/psyllium (N=47), nopal (N=44), or placebo (N=42). The results revealed no significant differences in the relief of IBS symptoms assessed by the Global Symptom Question across the three groups. However, the incidence and severity of constipation and hard stools were notably reduced in the inulin/psyllium group (4.5%) compared with nopal (15.1%, P=0.026) and placebo (15.6%, P=0.02).

Additionally, the inulin/psyllium group exhibited a decreased Shannon Diversity Index (4.0) in contrast to both nopal (4.4, P=0.024) and placebo (4.5, P=0.016). In particular, inulin/psyllium resulted in a lower abundance of Ruminococcus(P=0.001), Dorea (P=0.016), and Coprococcus (P=0.011) and higher Bifidobacteria (P=0.055). These changes were not associated with short-chain fatty acid production alterations, suggesting a unique effect on the gut microbiome’s composition.

Overall, the co-administration of inulin and psyllium was shown to mitigate constipation without exacerbating IBS symptoms, despite not leading to overall clinical improvements. These findings suggest the potential for personalized fiber-based interventions in IBS management, based on individual symptom profiles and microbiota configurations.

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