Causes Of Irritable Bowel Syndrome (IBS)
What causes IBS?
The cause of Irritable Bowel Syndrome is actually not completely understood. There is a lot of information we have obtained recently so that we understand it slightly better, but it's not completely known. The key mechanism underlying Irritable Bowel Syndrome is that the brain and the gut don't communicate normally. There's some deregulation or alteration between the brain and gut. And that communication, if it gets deregulated, leads to deregulations or alterations in the way the bowel functions. And that can effect how fast or slow the bowel moves so you can get diarrhoea if it's moving too fast, and constipation if it's moving too slow. If the bowel becomes more sensitive than it should be or what we term "hypersensitive," the patients usually present with pain, bloating, permeability to the bowel or secretion and it can lead to mucus in the stool or change in stool form. But there's a lot of factors that play a role in the deregulate brain-gut communication. So there are more emotional, psychological factors and physical factor to consider. For example, there is a subgroup of patients with Irritable Bowel Syndrome who actually developed the condition after they suffered a gastroenteritis or a bowel infection. Now, we all have bowel infections and not everybody gets Irritable Bowel Syndrome but about ten percent of IBS patients actually had a previous documented gastrointestinal infection. And then even though the infection clears, they develop abnormalities in their bowel that lead them to have IBS symptoms. And it also looks like there's a genetic predisposition to getting Irritable Bowel Syndrome. There's some studies that have shown that they can cluster in families or in twin cities have spread. So that's actually an exciting area of research for IBS.
Can stress make IBS worse?
I think stress can increase the predisposition or the vulnerability of an individual to get Irritable Bowel Syndrome. Chronic or sustained stress is associated with an exacerbation or the onset of IBS. I don't mean acute stress that occurred just that day, but usually it's chronic or sustained stress. But actually the animal model of IBS is based on putting the animal at a neo-nate period under a stressor or what we term an early adverse life event, and as an adult the animal has the same behavior as an IBS patient. So there's probably things that go on early in life that probably lead to the breakdown of adaptive stress responsive systems leading the individual to develop or being predisposed to developing Irritable Bowel Syndrome. When you get IBS there is usually physical or psychological stressors that can cause the exacerbation of symptoms or even the onset of the symptoms.
What can I tell people who insist my IBS is 'all in your head'?
I think the best way to approach Irritable Bowel Syndrome (IBS) and trying to have a patient understand what they have is to explain that even though there's no anatomic or structural abnormality that we can see, the function of the body is not completely normal. Sometimes I use this analogy, and I'm not sure that this is the best analogy, but I'll say "If you see a car that looks perfect on the outside, that's the way the body can look, the bowel can look. But if the car doesn't start, it doesn't work normally. And that's kind of the same thing with the gastrointestinal tract; it's not functioning normally but anatomically and structurally it looks fine."
Does diet cause IBS?
The association of diet and IBS is not completely clear. We do know that about thirty to fifty percent of IBS patients will report that their symptoms worsen after meals. There is definitely patients who have a food intolerance, it's not so much a food allergy, it's a food interolerance. And if they eat something that their bowels do not tolerate, they'll develop symptoms of IBS. There is lactose intolerance and fructose intolerance and some patients are intolerant of those products. Now, they can be coexistent with IBS meaning that even if, like for example, I'm lactose intolerant, if I stopped eating dairy products I won't have those lactose intolerant symptoms but I can still have symptoms compatable with IBS. So, they can actually be coexistent. So, they dont necessarily explain --if all my symptoms went away, then I don't have IBS. I just have lactose intolerance. So, even though there are food intolerances, they can just be coexistent but they can mimic IBS. Now, sometimes with patients when they're feeling well they can eat a lot of different types of foods. When they're not feeling well, they can't eat those foods. So, its very inconsistent. But there are patients who have food triggers and the patients should really do symptom diaries. I'm really thinking and believing that symptom diaries can be helpful. Just for a certain period of time because you don't want patients to only think about their symptoms but you want to gain more information that's going to be helpful to them. And they may find that there's certain food triggers that lead to a flare of their symptoms and its important for them to recognize that and avoid that. But there are different diets. In general, fatty foods stimulate the bowels more, they empty out of the stomach slower, they stimulate the colon more so patients will very commonly report when they eat fatty foods they feel worse. The other thing that I've found that's never been proven in a study, but I hear a lot of patients say this-- when they eat a large amount of food, like the volume, the amount, they'll have more symptoms. So, it's almost like the food is the stressor to the gut. It's not the particular food but the amount of the food itself that's being stressor.
Is it true that IBS can go away on its own?
There is information and studies that have shown that IBS can go into remission or go into a period where the patient symptoms go away, but that doesn't mean that the symptoms won't recur. In most individuals it will recur. They have actually done studies where they look at the overall prevalence of IBS, so it will be 10 percent of one time point. If you look at it years later the prevalence is still 10 percent. Some of those individuals, about 20 percent, won't have symptoms anymore but you will get new patients or new individuals that didn't have IBS previously who will now develop the symptoms. So the prevalence stays pretty steady, but patients can go in and out of having symptoms.
If my IBS goes away can it come back?
If the symptoms of IBS go away, they can come back, they don't always but they can. What's interesting is they have found that if you look at more of the elderly population as we age, the incidence of IBS, or prevalence of IBS actually decreases. But I saw one study that showed that the prevalence of IBS actually decreased in women as they age, but it stayed pretty steady in men.
Is IBS hereditary?
There is increasing evidence that there is a genetic predisposition, or that there is some hereditability associated with IBS. We do not completely understand that, but there are twin studies that have shown that identical twins will have a greater concordance of having IBS. It means that if one twin has it, the identical twin is more likely to have it than non-identical twins, where you don't share the same amount of genetic material. But what's interesting about those twin studies is it shows that even though there is a genetic factor that's important in IBS, the environmental factors are probably just as important, if not more important. So it's really multi-factorial.
Are there risk factors for IBS?
There are some risk factors and some of the risk factors include an infection. I think also having a family member, particularly a first degree family member with a condition. The other factors I thought to play a role, but I'm not sure I would term it a risk factor, is having chronic stress or having psychological distress in the form of anxiety or depression. Or this term called somatisation, where patients have different symptoms that are focused on different organ systems of the body. That probably predisposes them to a developing those symptoms. The other risk factor would be, if you have other chronic pain syndromes. Very often these chronic pain syndromes go hand in hand, so there are significant overlaps with IBS with migraine headache, with fibromyalgia, with introstiltialsistitis where patients have pain that's referable to their bladder. So those are conditions that if you have it, it's very often that you'll see IBS in those individuals.
Can colic as a baby lead to IBS as an adult?
It's a good question if colicky babies are more likely to develop IBS. That has been a hypothesis. I know at a recent paediatric gastroenterology meeting that, even though there isn't great data, the data that is available shows that it's actually not predictive of who gets IBS. If you are a colicky baby, it doesn't necessarily predict that you'll get IBS later. It seems to make sense that it would happen, but it has not necessarily been proven in studies.
