Pages

Irritable bowel syndrome (IBS) is a common condition and one that generally requires substantial patient involvement for effective management. The lack of a defining “test” to prove its existence can be a clinical challenge, and the distressing gastrointestinal discomfort and other symptoms can lead to patient frustration. Even when a diagnosis seems clear, further referral may be necessary to rule out other potential conditions due to persistent symptoms.

Where no red flags are present, symptom resolution with appropriate management can prevent unnecessary referral, be it through pharmacological treatment or diet. It is always satisfying to be able to offer little titbits on dietary management that can improve people’s quality of life and experience of their condition without increasing consultation time.

Two recently updated pages on GPnotebook cover some practical dietary aspects of IBS and can be found here and here. They have some nice practice pearls.

The first page linked to, on fibre intake, offers some tips that were new to me, including on how much fibre people should be taking, and which types of fibre help IBS and which make it worse.

To start, how much fibre is needed? The updated page suggests that a fibre intake of about 25–35 g per day, added slowly, can help prevent gas and bloating in people living with IBS.

The page also states that not all fibre carries equal value, with fibre being divided into soluble or insoluble. Most international guidelines recommend soluble as opposed to insoluble fibre for the treatment of global IBS symptoms.

So, what is the difference? Well, dietary fibres are a variety of non-digestible plant-based carbohydrates that are not absorbed by the small intestine, impact the digestive system and variably interact with colonic microbiota. Insoluble fibres are found in the peelings of fruits and vegetables, seeds, whole grains and wheat bran. Examples of whole grains include barley, bulgur, quinoa, and black, brown and red rice. Many of these food sources are common and can have other health benefits; but, unfortunately, the insoluble fibres that they contain can increase stool bulk while stimulating colonic motility and mucus production and can contribute to common IBS symptoms such as bloating and abdominal discomfort. Soluble fibre, in contrast, dissolves in water and forms a gel-like consistency in the gut, and it is available from several dietary sources, such as oat bran and the flesh of fruits and vegetables.

Psyllium is a soluble fibre, easily available over the counter, which holds water in the lumen of the intestine and improves colonic transit without worsening IBS symptoms, especially in those with IBS with constipation. It has been shown in randomised placebo-controlled trials to reduce IBS symptoms.

The other updated GPnotebook page that I referred to above is on FODMAPs and IBS. This is a concept I am more familiar with, but I found it useful how the page breaks down exactly what FODMAPs are (fermentable oligosaccharides, disaccharides, monosaccharides and polyols) and explores the mechanism by which they worsen symptoms in people with IBS.

The page explains that FODMAPs are poorly absorbed in the small intestine and reach the colon undigested. This is turn causes an osmotic increase of water content in the intestines and increased gas production due to bacterial fermentation. This phenomenon occurs both in people with and without IBS. With the latter, it is thought to cause symptoms through visceral hypersensitivity and altered motility.

The updated page also goes over how a FODMAPs diet in IBS should work. In particular, it notes that a treatment course with the low-FODMAPs diet commences with an elimination period of 4–8 weeks, excluding or restricting foods high in FODMAPs.

The page also signposts a great patient information resource that we can direct our patients living with IBS to, for learning more about how to use fibre and FODMAPs to improve their symptoms.