This is a very good trial of the use of dietary fibre in the treatment of IBS. Increasing the intake of dietary fibre (either insoluble or soluble) is a universally advocated for the treatment of irritable bowel syndrome
No previous study on this treatment had been undertaken on its effects in the primary care setting, where the vast majority of these patients are managed The objective of this randomised blind trail was determine the effectiveness of increasing the dietary content of soluble fibre (psyllium) or insoluble fibre (bran) in patients with irritable bowel syndrome in a General practice setting with 275 patients aged 18-65 years with irritable bowel syndrome. The trial was 12 weeks of treatment with 109 psyllium (n=85), 10 g bran (n=93), or 10 g placebo (rice flour) (n=93). The primary end point was adequate symptom relief during at least two weeks in the previous month, analysed after one, two, and three months of treatment to assess both short term and sustained effectiveness. Secondary end points included irritable bowel syndrome symptom severity score, severity of abdominal pain, and irritable bowel syndrome quality of life scale. The proportion of responders was significantly greater in the psyllium group than in the placebo group during the first month (57% v35%; relative risk 1.60,95% confidence interval 1.13 to 2.26) and the second month of treatment (59% v 41 %; 1.44, 1.02 to 2.06). Bran was more effective than placebo during the third month of treatment only (57% v 32%; 1.70, 1.12 to 2.57), but this was not statistically After three months of treatment, symptom severity in the psyllium group was reduced by 90 points, compared with 49 points in the placebo group (P=0.03) and 58 points in the bran group (P=0.61 versus placebo). No differences were found with respect to quality of life. Fifty four (64%) of the patients allocated to psyllium, 54 (56%) in the bran group, and 56 (60%) in the placebo group completed the three month treatment period. Early dropout was most common in the bran group; the main reason was that the symptoms of irritable bowel syndrome worsened.
Bijkerk et al 2009 Soluble or insoluble fibre in irritable bowel syndrome in primary care? Randomised placebo controlled trial. BMJvol 339 pp 613-615
My own practice was a mix of the two forms of fibre, bran for breakfast and an apple and an orange a day.