Soluble fibre is an effective treatment for irritable bowel syndrome, but insoluble fibre may worsen symptoms, according to new research.

Scientists at University Medical Centre Utrecht in the Netherlands randomised 275 patients aged 18 to 65 years with irritable bowel syndrome to receive either 10g of psyllium (soluble fibre), bran (insoluble fibre), or placebo (rice flour) twice a day for 12 weeks. Patients were assessed at one, two and three months for symptom relief, severity of abdominal pain and quality of life, using standard scoring scales.

Findings showed that psyllium was the most effective treatment for irritable bowel syndrome, with a significantly greater number of patients reporting adequate symptom relief and a reduction in symptom severity.

After three months of treatment, symptom severity was reduced by 90 points in the psyllium group, 49 points in the placebo group, and 58 points in the bran group. However, no differences were reported between the groups in abdominal pain or quality of life.

The researchers said bran showed no clinically relevant benefit. "Many patients seemed not to tolerate bran and the dropout rate was highest in this group," they reported.

They added: "These results support the addition of soluble fibre such as psyllium, but not bran as an effective first treatment approach in the clinical management of irritable bowel syndrome. Indeed, bran may worsen symptoms of irritable bowel syndrome and should be advised only with caution."

Irritable bowel syndrome is characterised by abdominal pain and an irregular bowel habit, and affects an estimated 10% of the population. Increased intake of dietary fibre, often in dietary supplement form, is usually recommended to help alleviate symptoms, but experts say there is limited evidence that this treatment actually works.

Source:British Medical Journal
2009; Volume 339:b3154, Published 27 August 2009, doi:10.1136/bmj.b3154
"Soluble or insoluble fibre in irritable bowel syndrome in primary care? Randomised placebo controlled trial"
Authors: C.J. Bijkerk, N.J. de Wit, J.W.M. Muris, P.J. Whorwell, J.A. Knottnerus, A.W. Hoes