According to a recently published study, psyllium reduced inulin-induced colonic gas production in patients with Rome IV criteria irritable bowel syndrome (IBS). In the study, published in the journal Gut researchers investigated whether the administration of psyllium with inulin would diminish the production of colonic gas in patients with IBS.
The randomized, four-period, four-treatment, placebo-controlled, crossover trial included 19 patients (78% women, median age 39 years) with Rome IV criteria IBS diarrhea (n = 10) or IBS-constipation (n = 9) who ingested a 500-mL test beverage that contained 20 g of inulin, psyllium, combined inulin and psyllium, or dextrose. The researchers measured breath hydrogen every 30 minutes for 6 hours, and an in vitro fermentation model evaluated fecal samples from a subset of patients.
The primary endpoint was colonic gas assessed by MRI. Colonic gas rose steadily from 0 to 6 hours, with inulin causing the greatest rise, average (IQR) AUC(0–360 min) 3,145 (848-6,502) mL/min. This was significantly reduced with inulin and psyllium coadministration to 618 (62-2,345) mL/min (P = .02) and not significantly different from placebo. Colonic volumes AUC(0–360 min) were significantly larger than placebo for both inulin (P = .002) and inulin-and psyllium coadministration (P = .005). Breath hydrogen rose csignificantly from 120 min after inulin but not following psyllium; coadministration of psyllium with inulin delayed and reduced the maximum increase, AUC(0–360 min), from 7,230 (3,255-17,910) parts per million (ppm)/hour to1,035 (360-4,320) ppm/hour (P = .007).
The researchers concluded that psyllium produces an increase in colonic volumes without increasing colonic gas or breath hydrogen. They also noted that psyllium is only slowly fermented by IBS fecal microbiota, and that combining psyllium with inulin diminishes both colonic gas and breath hydrogen response in patients with IBS but in vitro does not impair fermentation. Whether coadministration with psyllium increases the tolerability of prebiotics in IBS warrants further study.
The authors also suggested that by taking viscous, poorly fermented fibers such as psyllium when low fermentable oligosaccharide, disaccharide, monosaccharide, and polyols (FODMAP)–rich foods are eaten, it may be possible to achieve the reduction of colonic gas symptoms seen on a low-FODMAP diet without disturbing the microbiota or requiring severe dietary restriction.
The researchers concluded that their mechanistic study demonstrated that adding psyllium to inulin reduces gas production in patients with IBS and suggests that, by choosing diets with adequate amounts of viscous fiber, patients may be able to obtain the prebiotic health benefits of a high-fiber diet without exacerbating their IBS symptoms, particularly flatulence. Larger clinical trials, they added, are needed to confirm the clinical value of these mechanistic insights.
David Gunn, Nottingham Research Center, and colleagues, wrote, "The connection between intestinal gas and gut symptoms is complex as signaling from gut to brain is influenced by many factors in patients with IBS. Although cross-sectional studies of unselected patients with IBS have not shown excessive intestinal gas compared with healthy controls, increases in gas have been related to symptom induction. Inulin-type fructans worsen some symptoms in IBS particularly when given at higher doses. Alternative approaches to control of colonic fermentation in IBS are therefore being actively pursued."
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