According to a study published on, doctors should recommend fiber, antispasmodics, and peppermint oil as first-line treatments for irritable bowel syndrome (IBS). Recent proof of the effectiveness of these treatments should also lead to changes in the national guidelines that specify how to manage IBS.

Affecting between 5% and 20% of the population, IBS is a condition that causes abdominal pain and irregular bowel movements. Currently, it is difficult to treat IBS because we do not know exactly what causes it. Usual therapies consist of fiber supplements, probiotics, antidepressants, hypnotherapy, and laxatives. This treatment uncertainty, however, has resulted in the promotion of complementary and alternative treatments by international and national bodies. An example of this is the recently-published National Institute of Health and Clinical Excellence (NICE) guidelines on the management of IBS.

Therapies to treat IBS such as fiber, antispasmodics and peppermint oil have been studied, but their effectiveness has not been proven due to conflicting conclusions and errors in analysis. To further clarify the effects of these treatments, Dr. Alex Ford (McMaster University, Ontario, Canada) and colleagues conducted a review and meta-analysis of randomized trials. The trials – totaling over 2500 adult IBS patients – compared fiber, antispasmodics and peppermint oil to placebo or no treatment.

The researchers found that all three therapies were effective IBS treatments compared to placebo or no treatment. In order to prevent IBS symptoms in one patient, 11 people needed to be treated with fiber, 5 with antispasmodics, or 2.5 with peppermint oil. In addition, there were no serious adverse effects associated with the treatments.

In the twelve papers (591 patients in total) that analyzed fiber, insoluble fiber such as bran was not found to be beneficial while isphaghula husk (soluble fiber) was found to significantly reduce symptoms. There were 22 studies with 1,778 patients that focused on various antispasmodics. The researchers found that hyoscine most successfully prevented IBS symptoms. Hyoscine – extracted from the cork wood tree – is also recommended by the authors to be the first-line antispasmodic therapy in primary care.

According to four trials involving 392 patients, peppermint oil appears to be the most effective treatment among the three.

Although these treatments are effective, safe, and available over the counter, they have been overlooked after newer and more expensive drugs were introduced. Since all three treatments have been shown to be potentially effective therapies for IBS, “Current national guidelines for the management of the condition should be updated to include these data,” conclude the authors.

An accompanying commentary written by Professor Roger Jones (King’s College London) argues that the results of this study should, “reawaken interest in the pharmacotherapy of irritable bowel syndrome and stimulate further research.” He adds, however, that, “None of these data, of course, invalidate the importance of making a ‘holistic’ diagnosis in irritable bowel syndrome – that takes into account physical, psychological, and social factors – and of planning an integrated approach to treatment, which deals with all of these factors.”

Effect of fibre, antispasmodics, and peppermint oil in the treatment of irritable bowel syndrome: systematic review and meta-analysis
Alexander C Ford, Nicholas J Talley, Brennan M R Spiegel, Amy E Foxx-Orenstein, Lawrence Schiller, Eamonn M M Quigley, Paul Moayyedi
BMJ (2008). 337:a2313
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Written by: Peter M Crosta