What is irritable bowel syndrome (IBS)?
IBS is a disorder of the functioning of the digestive tract. This causes abdominal pain and an alteration in bowel habit (constipation or diarrhoea or both). It is the commonest diagnosed gastrointestinal condition and affects up to 20% of the UK population. It is second only to the common cold as cause for absence from work.
What are the symptoms of irritable bowel syndrome?
The symptoms usually begin in early adulthood and affect women twice as often as men. Abdominal pain and bloating are the most common symptoms and may be triggered by food or stress and relieved by bowel movement. Diarrhoea, constipation, or both are also common as is the feeling of not having emptied the bowel completely. Other symptoms may be indigestion, nausea, urinary symptoms and painful menstrual periods.
Unexplained weight loss or bleeding are not due to IBS and should be investigated separately.
What are the causes of irritable bowel syndrome?
Despite much research, the cause is still unknown but is likely to be due to several factors. There are a number of theories why some people develop IBS:
In some people abnormal, vigorous contractions of the intestines cause cramping abdominal pains i.e. the muscles of the intestine walls are contracting abnormally. Medications that reduce contractions such as antispasmodics, may help such patients.
In other people the intestines are working normally but normal contractions (or gas) are interpreted in the brain as being excessive (known as ‘hypervigilance’). Such patients sometimes benefit from medication that decreases pain perception.
Different foods may worsen the symptoms of IBS. It is not known if this is due to an allergic reaction or due to an intolerance (e.g. to diary or sugar). The easiest way to detect an association between different foods and the symptoms of IBS is to eliminate different food groups systematically. This is best achieved using an ‘elimination diet’ which is supervised by a specialist dietician. We can make a referral for diet manipulation.
A minority of people develop IBS after a gastrointestinal infection (e.g. campylobacter or salmonella). The way that these infections cause IBS is still unknown but it is possible that a low-grade inflammation persist in the intestine in such people.
What are the diagnostic tests?
There are no specific diagnostic tests for IBS, although necessary tests will vary depending upon the type of symptoms. Blood tests, stool tests (for infections, blood or inflammatory proteins), breath tests (for sugar malabsorption), radiology (ultrasound, CT or MRI scans) and endoscopic procedures (gastroscopy, colonoscopy or wireless capsule endoscopy) may be useful. Several intestinal disorders with similar symptoms usually need to be excluded. These include inflammatory bowel disease (ulcerative colitis, Crohn’s disease and microscopic colitis), malabsorption (e.g lactose), coeliac disease, or colon cancer.
What treatments are available?
Irritable bowel syndrome treatment is often a long-term process and although IBS cannot be completely cured it is usually possible to control symptoms and minimise the impact on daily life.
If possible ‘trigger factors’ such as food intolerance or stress should be identified and treated. A specialist dietician and chronic fatigue clinic may be able to help.
The different drug treatments will depend upon the predominant symptoms and must be weighed up against the possible side-effects. Complementary treatments (such as probiotics, herbal remedies, homeopathy, candida-free diets) may be tried, but unfortunately the benefit of these is not proven. Hypnotherapy however in clinical trials does benefit some patients and in now within NICE (National Institute for Clincal Excellence) guidelines.