A randomised, placebo-controlled trial in healthy humans of modified cellulose or psyllium evaluating the role of gelation in altering colonic gas production during inulin co-administration

was assessed by breath hydrogen measurements for 24 hours after ingestion. While psyllium significantly reduced initial breath hydrogen production compared to the placebo, a non-inferior effect on reduction in initial breath hydrogen with methylcellulose was not demonstrated. Despite similar physicochemical properties, psyllium and methylcellulose hydrogels exhibited different transit behaviour based on the breath hydrogen time to rise >10 ppm and time to peak. We hypothesise that the fast reformation of psyllium's polysaccharide network or "self-healing" properties after deformation by intestinal pressure waves may underpin its effectiveness in slowing fermentation. The clinical trial registry number is NCT05911347 (https://clinicaltrials.gov).