Irritable bowel syndrome (IBS)

Individuals usually complain of recurrent abdominal pain which may vary in site and severity and is often associated with variable stool form and frequency. Abdominal distension or bloating may be a feature. IBS is a functional condition; the symptoms are absolutely genuine but are not due to an identifiable disease process or detectable abnormality on investigation.

Studies suggest that IBS is much more common in women.The symptoms may follow an infection or an episode of food poisoning in about 20% of cases (so-called post-infective IBS). IBS may be worse at times of stress. Physical examination, stool culture and blood test results are always normal in IBS; if an abnormality is detected then the diagnosis should be reconsidered.

Treatment is difficult but usually involves treating the predominant symptom. For example, if diarrhoea is the main problem then loperamide may be tried. In people with post-infective, diarrhoea-predominant IBS ondansetron or colesevalam (in case of co-existing bile salt malabsorption) may be of some help.

There is a new treatment for people with moderate-severe IBS with constipation (IBS-C). The drug is called linaclotide and may be prescribed to improve symptoms of abdominal pain, bloating and constipation in adults with IBS-C. See Patient Information sheet for more information.

Treating pain may be more challenging and a variety of different drugs may be tried; simple remedies such as peppermint oil capsules,alverine or mebeverine may be tried first and if unsuccessful, progressing to hyoscine (Buscopan). In more severe cases, drugs affecting the levels of serotonin in the gut (and the brain), such as citalopram, may be tried or in those whom are unkeen on drugs, cognitive therapy or hypnotherapy may be considered.

Some people with diarrhoea and abdominal bloating thought to be due to IBS may respond to treatment with probiotics, antibiotics (see Patient Information sheet on Small Intestine Bacterial Overgrowth) or a gluten-free diet (in absence of coeliac disease).

There is increasing interest in the relationship between certain dietary sugars and IBS. Researchers from Monash University in Australia found that removing certain fermentable sugars from the diet helped up to 75% of people with IBS. A low FODMAP (Fermentable, Oligosaccharides, Disaccharides, Monosaccharides And Polyols) diet. These substances may be poorly absorbed in the small intestine and then act as a food source for bacteria in the large intestine (colon); it is this process which may produce gas and draws in liquid leading to nausea, flatulence, diarrhoea and bloating.

Low FODMAP Diet for IBS

From the point of view of nutrition, the foods you eat e.g. eating broccoli which may cause bloating or too much or too little fibre, can impact on all types of IBS.

You may have heard that a low FODMAP diet can help IBS – yes, this can be very helpful. FODMAP foods, when processed by your digestion, can produce gas. This gas can cause bloating, and abdominal discomfort.

FODMAP foods resist complete digestion; they pass into the large intestine or colon where the bacteria in your colon ferment these foods; this produces gas which in excess causes the discomfort you experience. FODMAP foods are not bad foods. In fact they are a fuel for the friendly bacteria. But some people are more sensitive to the effect of FODMAPs foods.

To help reduce your symptoms we recommend you find out what FODMAP foods your digestion is reacting to. FODMAP foods are common foods that have health benefits e.g. garlic, avocado and beetroot, but when eaten in specific amounts usually more than your digestion can handle will cause these digestive symptoms. It does not do you any harm to eat these foods, if you do get symptoms there will be no long term damage. But it is recommended that for a period of time you reduce FODMAP rich foods and then you can have a trial period where you re-introduce into your diet to see how your digestion handles them.

It is important to get guidance as many people remove a lot of foods from their diet. We must remember that most plant foods contain carbohydrates and it’s important to not overly restrict your diet. Having a nutritional and dietary assessment and plan will help you to manage your diet and get the symptom control you seek by following a low FODMAP diet.


At Digestive Health City & Docklands, we work hard to provide our patients with top-class care. You will enjoy friendly, fast and modern treatment by a highly experienced gastroenterologist. We carefully review patient satisfaction and feedback, and at Digestive Health we are continuously making improvements to our services, ensuring the highest level of care possible.

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120 Old Broad Street, City, EC2N 1AR

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