As many as 20 percent of the adult U.S. population, or one in five Americans, have symptoms of irritable bowel syndrome (IBS), making it one of the most common disorders diagnosed by doctors. Satish Rao, MD, PhD, gastroenterologist at University of Iowa Hospitals and Clinics, talks about IBS:
What is irritable bowel syndrome?
Irritable bowel syndrome, commonly also known as IBS, is a common gastrointestinal problem that affects up to 15 to 20 percent of the U.S. population. It is usually defined as abdominal discomfort or pain associated with an altered bowel habit such as diarrhea, constipation, or abdominal gas and bloating that persists for several months—at least three months in the course of a year—so then we call this irritable bowel syndrome.
What are the symptoms of IBS?
The symptoms of IBS include:
- Abdominal discomfort or pain
- Bloating
- Constipation with irregular bowel habit such as excessive straining,
- Diarrhea that persists for several weeks to months and doesn't respond to usual therapy
These are usual, common symptoms, but IBS can mimic many other common gastrointestinal conditions. We only diagnose IBS when we've excluded common gastrointestinal disorders as an underlying cause.
What causes IBS?
We really don't know what causes IBS. Initially it was thought it was a motility disorder, meaning that the gut has become overactive in patients with diarrhea, or underactive or lazy in patients with constipation.
Some people believe that it is related to stress, depression, or anxiety. In the last five to 10 years, research is revealing that the main problem seems to be in brain/gut interaction. In other words, how gut perceives information and how it feeds this information to the brain; how brain receives this information and interprets this information. Somewhere in this brain/gut axis or brain/gut interactions, there seems to be a problem which then manifests with these symptoms.
When should someone who suspects they may have IBS see a gastroenterologist?
I think it is important that patients recognize these symptoms and because IBS mimics other common gastrointestinal disorders, they should be carefully evaluated for:
- Blood in stools
- Weight loss
- Anemia
- Mass revealed by abdominal examination
These are common, more serious gastrointestinal disorders that should be excluded. If there is evidence of these, then patients must be referred to a gastroenterologist for an evaluation. If they're absent, a physician may try simple therapies to alleviate this problem; but if patients don't respond, they should be immediately referred to a gastroenterologist for more definitive diagnosis and management.
How is IBS diagnosed?
We do a variety of tests to better understand the nature of the symptoms. There is no single marker that tells us clearly that this is IBS, but we do certain tests. For example, patients with gas and bloating may have lactose intolerance—inability to digest dairy products—or fructose intolerance—inability to digest fruit related products. We test to study the speed at which things go through the gut, and we put a balloon in the rectum and do balloon distention studies. This reveals whether the patient's gut is normal in sensation or is hypersensitive, a hallmark of many patients with IBS. Their gut generally perceives information at thresholds that mostl people don't perceive. This hypersensitivity is what we can detect with tests.
What is the treatment for IBS?
The treatment for IBS depends on a generous explanation of the problem and reassurances that although the symptoms appear serious, they are not due to a serious sinister pathology.
But that alone will not do the job because patients have significant symptoms. Today we have drugs that are FDA-approved. One is called Alosetron which treats IBS with diarrhea. Alosetron is a serotonin compound that slows gut motility and relieves symptoms of discomfort, pain, and diarrhea.
Likewise, we have a drug called lubiprostone, or amitiza, which at a dose of 8 micrograms twice a day has been approved by the FDA for treatment of irritable bowel syndrome with constipation-predominant symptoms.
So these two drugs are FDA-approved for the treatment of IBS, but still this only appears to improve symptoms in about 40 to 50 percent of patients; and one-half of patients still don't respond to this treatment and we are in search of newer drugs. Sometimes symptomatic treatment with over-the-counter laxatives or antidiarrheal preparations and antispasmodic preparations may be useful in the management of these patients.
Can stress or diet changes affect IBS?
Yes, initially there was presumption that stress indeed causes IBS, but we now know that stress does not actually cause the condition, but seems to be an important co-factor in this problem. Many patients, when we test them formally, show signs of depression, anxiety, paranoia, and so on and so forth. Many of them have sleep disturbances.
What we also know is IBS tends to overlap with many other common problems, such as fibromyalgia, interstitial cystitis, and many other conditions. With regard to stress, I think it makes sense that if we can relieve stress inducing factors, then this can improve IBS. Dietary changes can also be very important. If patients consume dairy foods and they are lactose intolerant then they can get symptoms of IBS; or fructose intolerance—which is the fruit sugar—present in a number of products, including high fructose corn syrup and pop and so on and so forth. If they can avoid those, they can get significant relief of symptoms.
If a patient has IBS, could it also be linked to other health problems?
Yes. IBS is a mimic of many GI disorders. But more importantly, it overlaps with fibromyalgia, sleep disorders, interstitial cystitis, and other GI problems, for example functional dyspepsia—more upper gastrointestinal symptoms—or unexplained, non-cardiac chest pain. All of these are an overlapping nature of symptoms and sometimes they present with upper gut symptoms and sometimes they present with lower gut. Usually we refer to the lower gut symptoms as IBS.
Is UI Hospitals and Clinics involved with any research on IBS?
Yes, we are doing some very exciting research in a number of areas related to IBS.
One is in investigating the association with fructose in fruit intolerance, but also looking at some new diet issues. There is an important dietary product called fructan, which is commonly present in things like wheat, broccoli, onions, and so on. This is a sugar that is present in this wheat and we believe that in some patients they have an inability to digest these fructan products that can cause IBS-like symptoms.
Likewise we're looking at some new treatment options, there are some drug studies that we're doing in collaboration with industry sponsors, and we're also looking at, from a mechanistic perspective, how the gut and brain are interacting in these people and trying some treatments such as maybe temporarily treating the brain areas that are involved in causing IBS and seeing whether some form of magnetic treatment for this may help to alleviate these problems. So there's a lot of exciting research that we're conducting at the University that may help some of the patients with these problems in the future. |
