What is Irritable Bowel Syndrome?

The science behind IBS and what can be done to help sufferers.
25 April 2017

Interview with 

Dr Anthony Hobson - Functional Gut Clinic, London


male and female stick people needing the toilet


One problem that afflicts the intestine is Irritable Bowel Syndrome (IBS). Up to 20% of the adults in developed countries are affected by IBS, but what is it? And how can it be treated? April is IBS awareness month so we thought we’d better find out! Chris Smith spoke to clinical scientist Anthony Hobson.

Anthony - IBS is characterised by a set of symptoms. So symptoms like bloating, abdominal pain, altered bowel habit, and really it’s a diagnosis of exclusion. What I mean by that is if you go to your GP with those symptoms, then what he will do is try and exclude a serious cause for those things. Red flag symptoms such as bleeding, weight loss and so forth, and if he’s quite confident these symptoms are not caused by anything more serious, then he will give you a diagnosis of IBS. If you find yourself in secondary care, then that diagnosis of exclusion goes further with things like stool tests, imaging tests, and colonoscopy.

Chris - Tell us a bit about those. So someone comes to you with a set of those symptoms - what sorts of things will you do to them in order to work out what is causing them to have IBS type symptoms?

Anthony -  There’s a kind of triage process which a lot of patients should be able to treat their symptoms with self-help. There are lots of good self-help guides out there from places like the IBS Network which can help you to modify your diet for instance, and try and eliminate those things that cause most of your symptoms.

However, some people can’t do that so the next process is to, within those guidelines, is to seek help from a dietician who can help you to modify your diet and treat things in that way.

Chris - So is it usually a change of diet that trigger it then? Or is it that is just comes on in some people, at some point, and then they’ve got to deal with it?

Anthony - It can be like that in terms of people will change their diet. They may go to a different country or they may start eating a different diet - a healthier diet maybe with a lot more fruit and vegetables and that upsets the system, but there are other causes for IBS as well.

Chris - Say this happens to somebody, because I know you said you can get investigated, what sorts of things are you measuring from somebody which will then say yes, we think this is IBS and therefore the right sorts of treatments will be ‘X’ for you?

Anthony - Even before you get to diagnostics tests, the things you can do is try and exclude something. The commonest one is the protein gluten, so people will do a gluten exclusion test, see if they feel better, and then reintroduce it and see if symptoms com back.

Anthony - A similar thing can be done for milk proteins, so if things like beta casein. There are different types of milk proteins so the A1 protein in regular cow's milk can have more of an immunological effect as compared to A2 milk which is from other breeds of cattle, goats and sheep. So there’s simple tests that you can do yourself to try to understand whether your body is digesting things properly.

Chris - I did here one person say that probably what is happening is that some component of the diet, in some way, selects for a cross section or population of microbes and this shifts the whole population - a bit like a bacterial domino effect going off and you upset the applecart and that then causes the symptoms. And actually by withdrawing certain foodstuffs slowly you encourage the microbiome to reset itself.

Anthony - Certainly, as the other speakers alluded to, complex carbohydrates get broken down in the colon. And if you have too many of these or you’re not absorbing these carbohydrates properly, such as fruit sugars or milk sugars, then this can affect the microbiome. By withdrawing those difficult to digest carbohydrates, then you can reset the microbiome and get rid of some of those symptoms.

Chris - One thing that we covered a few weeks ago on the programme was an apparent link between stress and IBS. And people were saying if they make an animal, or take a human who’s stressed who’s got IBS symptoms they can take some of the bacteria from their gut, give them to animals and they can make an animal have IBS, like it’s almost transmissible.

Anthony - The microbiome can release certain neurotransmitters into the lumen and that can affect your mood. The way we look at is there are two types of stress - there’s a physiological stress and there’s a psychological stress, and both have a bidirectional influence on IBS symptoms. So, if there’s a period of inflammation like food poisoning, then this can create a physiological stressor and that can change the local environment and visa versa. If someone is stressed or bereaved then that can also change motility and make the gut more suitable for different types of microbes.

Chris - When you take someone on and help them, what proportion of people do you think, with the sorts of interventions you’ve outlined, you can get better?

Anthony - Again, it’s a triage process. I think many people can deal with these symptoms themselves. If they can’t, then they need testing. One of the things we can test for is if the bacteria has stayed in the small bowel and has started to affect the way people digest food. This is called small intestinal bacterial overgrowth. It can be tested for with a hydrogen breath test and treated with a specific antibiotic but that tends to be done only when you’ve gone through these first stages.

Chris - So you start simple and sort of escalate?

Anthony - Yeah.


Add a comment