Randomised-controlled trial of a fibre supplement on the symptoms of irritable bowel syndrome

Abstract

The aim of this study was to assess the effect of coarse wheat bran on specific bowel function parameters and symptoms in patients with irritable bowel syndrome (IBS). A longitudinal, prospective, randomised, placebo-controlled trial was undertaken. The duration of treatment was eight to 12 weeks and this consisted of 10-20 g/day of coarse wheat bran or a low fibre placebo taken in addition to the normal diet. Twenty-eight outpatients fulfilling the Rome criteria for constipation-predominant IBS were recruited to the trial (14 in the treatment group; 14 in the placebo group). Twelve people completed the trial in the treatment group and ten in the placebo group. The main outcome measures included changes in symptoms recorded in a diary, changes in objective measurements of bowel function and subjective overall feelings of improvement. The bran group significantly increased their non-starch polysaccharide (NSP) intake over that of the placebo group (p < 0.05). Mean stool wet weight increased significantly more in the bran group than in the placebo group (p < 0.05), but other bowel function measurements and all recorded symptoms were not different. Many patients reported changes in bowel habit that were not reflected in the objective measurements. The addition of coarse wheat bran to the diet increased NSP ingestion and stool wet weight in this group of IBS patients, but no evidence was obtained that such treatment was of benefit to these patients, other than a placebo effect on symptoms.