If you have the type of IBS that leaves you prone to diarrhoea, as opposed to constipation, then you may have been wrongly diagnosed…..

As many as half a million people in the UK with stomach problems previously attributed to irritable bowel syndrome (IBS), could actually have another cause for their symptoms that is likely to be much easier to treat. Ideopathic bile acid diarrhoea (BAD) has really only appeared on the medical radar within the last decade, but there is now a growing understanding that it accounts for a significant proportion of the five million of so people troubled by IBS at some stage of their lives.

A typical person will secrete as much as 8 litres of digestive juices a day, including 500-1000mls of bile, nearly all of which is reabsorbed in the latter part of the bowel. In the case of bile, around 95% is recycled this way, but if the reabsorption process is hampered then irritant bile reaches the colon where it speeds up transit time causing diarrhoea.

Tell-tale signs suggestive of BAD include unusually coloured motions (they vary in colour but often contain greens or yellows), loose stools that float and are difficult to flush away, and needing the loo during the night. All of which may be worse after a particularly fatty meal (bile secretion varies depending on the amount of fat in the diet).

Although there are a number of recognised conditions – ranging from Crohn’s disease to a side effect of gall bladder removal or radiotherapy treatment for cancer – that can interfere with bile acid recycling, patients with these generally don’t end up with a label of IBS because there is an identifiable cause. However, in idiopathic bile acid diarrhoea (the type likely to be confused with IBS) there is no such demonstrable trigger and the problem is thought to be due to a genetic glitch in the transport system responsible for collecting the bile salts from the bowel and recycling them.

There is a special test to confirm the diagnosis but it not widely used as it is very expensive (as much as £600 per patient) and awaiting approval by the National Institute for Health and Clinical Excellence (NICE). A simpler way to pick up the problem is to offer patients a trial of therapy – prescribing a drug that mops up the excess bile salts to see if symptoms improve (something that typically happens within a few days).

The cheapest option is a granular product called colestyramine (Questran), which is mixed with at least 150mls of water or other liquids and taken three times a day. It sounds simple, but it has the consistency of wallpaper paste and a lot of people struggle to swallow it. There is a pill-form (Cholestagel) but while a month’s supply of colestyramine costs just over a tenner, the tablets costs nearly £100 so doctors are naturally reluctant to prescribe them. If the drugs work they need to be continued indefinitely to maintain any benefits.

A low-fat diet may also improve symptoms, and making breakfast and lunch the main meals of the day, and only snacking in the evening may reduce the need to get up during the night.

If any of this rings a bell with you then your first step should be to discuss your symptoms with your GP. He or she can initiate a trial of colestyramine and if it works well then it probably clinches the diagnosis. If the response is less clear cut then referral to a gastroenterologist may be warranted as they are the only ones who have access to the confirmatory test.

And even if your IBS symptoms don’t fit with BAD, you should take some consolation from the fact that doctors are beginning to take a fresh look at what many regard as a “dustbin diagnosis” – somewhere you put everyone that doesn’t fit into any other category.

IBS has always been a difficult condition to treat but that is not surprising given that it is not caused by one specific problem. The discovery of BAD will help a significant proportion of people with IBS and I very much doubt that it will be the last advance in our understanding of this common syndrome.

 For a definitive (if rather complicated) review of the diagnosis and treatment of BAD go to www.ncbi.nlm.nih.gov/pmc/articles/PMC3002596/


• The key features of IBS are abdominal pain or discomfort, bloating and a change in bowel habit that have gone on for at least six months and where no other cause (such as infection, colitis or diverticulitis) can be found

• In approximately a third of cases the predominant disturbance in bowel habit will be loose stools or diarrhoea (IBS-D). In another third, it will be constipation (IBS-C) and the remainder will alternative between the two

• IBS affects both sexes and can strike at any age but is most common in women in their thirties and forties