Irritable bowel syndrome (IBS) is a condition characterised by symptoms such as abdominal discomfort, bloating, wind and altered bowel habit. In conventional medicine, there is no real consensus on what causes IBS. IBS is what might be termed a diagnosis of exclusion. In other words, it’s the diagnosis that individuals end up with when tests have revealed there’s no conventional explanation for the symptoms (such as inflammatory bowel disease).
My experience in practice has led me to believe that IBS usually does have one or more specific underlying cause ” it’s just that these tend not to be tested for and/or recognised by conventional medicine. I find the top two causes of this condition are food sensitivity and an imbalance in the organisms that inhabit the gut. For more about this, see a previous blog post here.
Despite conventional medicine’s generally poor understanding of IBS, certain strategies do exist for its treatment. For example, some health professionals will advise that individuals with IBS increase their intake of fibre. In practice, I’ve found that this makes many patients worse. One potential explanation for this concerns wheat which is, in my experience, a common triggering factor in IBS. And when individuals are advised to consume more fibre, they almost inevitably opt for more in the way of high-fibre breakfast cereals and breads that are based on wheat.
Fibre as a treatment for IBS has been studied, and a review of the available evidence has been published in the British Medical Journal this week . There are two main sorts of fibre that have been studied in this context: bran (usually from wheat) and ispaghula (derived from plaintain). Bran was not found to bring a statistically significant reduction in the risk of persistent IBS symptoms, though ispaghula (also known as psyllium) did. Ispaghula was found to reduce the risk of persistent symptoms by 22 per cent.
This review also looked at other strategies for IBS, including drugs that reduce spasm in the gut wall known as anti-spasmodics. 12 agents were assessed, of which only 5 brought statistically significant improvements in symptoms. Curiously, some drugs licensed for use for IBS (e.g. mebeverine) did not seem to have any good evidence for them. Only two agents (otilonoium and hyoscine) showed, according to the authors, consistent evidence of benefit. Of these two, the one with the best evidence appears to be hyoscine (Buscopan).
One final treatment assessed by the review was peppermint oil. This folksy remedy turned out to be better than placebo, reducing risk of persistent symptoms by more than half (57 per cent).
Another way the effectiveness of a treatment can be assessed is to measure the number needed to treat the number of individuals that need to be treated for one to get benefit. This review found the following NNTs for the treatments they assessed:
NNT for fibre: 11
NNT for antispasmodics: 5
NNT for peppermint oil: 2.5
Of these three main approaches for IBS, peppermint oil looks like the stand-out winner. My preference is still to attempt to elucidate the true underlying cause of someone’s IBS symptoms rather than merely treating the symptoms (see link above). That said, peppermint oil represents a generally safe and effective option for those looking for some symptomatic relief from IBS.
1. Ford AC, et al. Effect of fibre, antispasmodics, and peppermint in the treatment of irritable bowel syndrome. BMJ 2008;337;a2313