Psyllium reduces inulin-induced colonic gas production in IBS: MRI andin vitrofermentation studies

Abstract

ObjectiveHealth-promoting dietary fibre including inulin often triggers gastrointestinal symptoms in patients with IBS, limiting their intake. Our aim was to test if coadministering psyllium with inulin would reduce gas production.DesignA randomised, four-period, four-treatment, placebo-controlled, crossover trial in 19 patients with IBS. Subjects ingested a 500 mL test drink containing either inulin 20 g, psyllium 20 g, inulin 20 g+ psyllium 20 g or dextrose 20 g (placebo). Breath hydrogen was measured every 30 min with MRI scans hourly for 6 hours. Faecal samples from a subset of the patients with IBS were tested using an in vitro fermentation model. Primary endpoint was colonic gas assessed by MRI.ResultsColonic gas rose steadily from 0 to 6 hours, with inulin causing the greatest rise, median (IQR) AUC(0–360 min) 3145 (848–6502) mL·min. This was significantly reduced with inulin and psyllium coadministration to 618 (62–2345) mL·min (p=0.02), not significantly different from placebo. Colonic volumes AUC(0–360 min) were significantly larger than placebo for both inulin (p=0.002) and inulin and psyllium coadministration (p=0.005). Breath hydrogen rose significantly from 120 min after inulin but not psyllium; coadministration of psyllium with inulin delayed and reduced the maximum increase, AUC(0–360 min) from 7230 (3255–17910) ppm·hour to 1035 (360–4320) ppm·hour, p=0.007.Fermentation in vitro produced more gas with inulin than psyllium. Combining psyllium with inulin did not reduce gas production.ConclusionsPsyllium reduced inulin-related gas production in patients with IBS but does not directly inhibit fermentation. Whether coadministration with psyllium increases the tolerability of prebiotics in IBS warrants further study.Trial registration numberNCT03265002.

Gut‐brain axis dysfunction underlies FODMAP‐induced symptom generation in irritable bowel syndrome

“…we acknowledge there might be putative differences between IBS subtypes. 47 However, IBS diarrhoea-predominant patients do not show a more favourable response to a low FODMAP diet compared to IBS constipation-predominant patients in published clinical trials 48,49 and a meta-analysis, 50 so we opted for a mixed sample to increase generalisability of our findings towards the entire IBS patient population. Our study was not adequately powered to analyse IBS subtypes groups separately.…”

“…Hence, our paradigm represents the best compromise to capture both gut and brain responses (both pre‐ and post‐infusion) within subjects' tolerance range. Third , we acknowledge there might be putative differences between IBS subtypes 47 . However, IBS diarrhoea‐predominant patients do not show a more favourable response to a low FODMAP diet compared to IBS constipation‐predominant patients in published clinical trials 48,49 and a meta‐analysis, 50 so we opted for a mixed sample to increase generalisability of our findings towards the entire IBS patient population.…”

Targeting the Gut Microbiota to Relieve the Symptoms of Irritable Bowel Syndrome

“…On the other hand, soluble fiber obtained from psyllium husk was beneficial for the treatment of IBS patients with constipation, as shown in meta-analysis in which total of 499 subjects were studied (relative risk of being symptomatic was 0.83, CI: 0.73-0.94) [10]. Moreover, recent data has shown that psyllium could significantly reduce the inulin-related gas formation in IBS patients [102]. The authors speculate that diet with adequate amounts of viscous fiber is able to increase tolerability of prebiotics in IBS patients (without exacerbating flatulence).…”

Communication between the gut microbiota and peripheral nervous system in health and chronic disease

“…Combining another prebiotic, psyllium, counteracted this side effect of inulin. 146 Numerous lines of evidence also point to disrupted tryptophan metabolism in IBS. 75 , 80 IBS patients also exhibit psychiatric comorbidities, such as heightened stress response mediated by the hypothalamic-pituitary-adrenal (HPA) axis.…”