RESUMO
BACKGROUND: Clinical guidelines provide limited and conflicting recommendations regarding dietary fiber supplementation in irritable bowel syndrome (IBS). Nopal (Opuntia ficus-indica) is a cactus plant fiber containing both insoluble and soluble fibers that may have therapeutic potential in IBS. Our aim was to evaluate the dose-response effect of extracted nopal fiber powder on symptoms in IBS. METHODS: We performed a 4-arm, double-blind, parallel, randomized controlled trial in 60 patients fulfilling Rome IV criteria for IBS. Patients were randomized and blindly allocated to receive either nopal fiber (10, 20, or 30 g/day) or placebo (30 g/day dextrose) for one week and to keep their usual diet. Symptom severity (Global Symptom Question, IBS-SSS, Gastrointestinal Symptom Rating Scale), stool frequency and consistency (Bristol Stool Form Scale), breath hydrogen response, and stool short-chain fatty acids (SCFA) were measured at baseline and follow-up. KEY RESULTS: Significantly more patients reported adequate relief of symptoms after 20 g/day (87%, p = 0.008) and 30 g/day (80%, p = 0.025) of nopal fiber compared to placebo (33%). More patients receiving 20 g/day nopal fiber (67%) had a > 50% reduction in IBS-SSS compared to placebo (20%, p = 0.027), whereas the 30 g/day dose induced more loose stools (p = 0.027). Response rates were similar among IBS subtypes. There were no differences in breath hydrogen or stool SCFA between groups. CONCLUSIONS AND INFERENCES: Nopal fiber supplementation at doses of 20 and 30 g/day was associated with short-term improvement in IBS symptoms, warranting a fully powered clinical trial of longer duration with symptomatic, physiological, and microbiological endpoints.
