|Irritable Bowel Syndrome (IBS)|
Irritable Bowel Syndrome (IBS) is an illness that interferes with the normal function of the colon (large intestine), characterized by abdominal pain or discomfort along with signs of bowel dysfunction, most commonly diarrhea and/or constipation. Although healthy people commonly experience these same symptoms occasionally, in IBS these symptoms are more severe or are experienced more frequently. Current figures suggest that 10-20% of the population may suffer from the disease and it is the most common gastrointestinal illness diagnosed by doctors in the western world. Historically, IBS has not been thought to result from or lead to physical damage to the colon, like in Inflammatory Bowel Disease (IBD), or lead to development of other, possibly more serious diseases. Research in recent years however, has advanced the understanding of IBS greatly with the recognition that physical factors and damage to the lining of the bowel may indeed be involved. There is also evidence linking IBS to other illnesses, particularly those covered by The Environmental Illness Resource. All of this will be explored in greater detail below.
As with all of the syndromes on this website, there is no one lab test or imaging technique that can be used to diagnose IBS. Although certain tests and investigations may be carried out, a diagnosis is primarily given on consideration of history, presenting symptoms and by ruling out other gastrointestinal diseases.
Tests carried out on patients presenting with gastrointestinal symptoms may include the following:
Blood Tests - A complete blood count is often done to check for anemia and other abnormalities. Other tests may be performed, including an erythrocyte sedimentation rate (indicates if tissue damage or inflammation is present) and a thyroid test.
Stool Tests - The most common fecal examinations check for an intestinal parasite or occult (hidden) blood in the stool.
Sigmoidoscopy or Colonoscopy - These direct visual examinations of the rectum and sigmoid portion of the large bowel (sigmoidoscopy) or the entire large bowel (colonoscopy) are performed with an endoscope. (See IFFGD Fact Sheet No. 114 for further information on these procedures.)
Barium Enema - This is a radiologic (x-ray) examination of the large bowel that is performed by taking x-ray pictures of the bowel after it has been distended with a barium-containing liquid and air. The amount of radiation involved is usually not worrisome, but women who are pregnant or unsure whether they are pregnant should tell their physician, as this test should not be done in such cases.
In addition, testing for lactose intolerance by means of a breath test, and other miscellaneous procedures may be carried out.
The Official 'Rome III' Diagnostic Criteria for IBS
At least 3 months, with onset at least 6 months previously, of recurrent abdominal pain or discomfort* associated with 2 or more of the following features:
*Discomfort means an uncomfortable sensation not described as pain.
Other symptoms that are not essential but support the diagnosis of IBS:
Although not included in the diagnostic criteria for IBS, mental and emotional symptoms are commonly present in patients with IBS. These may include depression, anxiety, panic attacks and insomnia. This should not be taken to mean that IBS is caused by psychiatric illness however, as not everyone suffering from IBS has depression, for example, and not everyone with depression has any gastrointestinal symptoms. It is a similar situation as with all the other "Environmental Illness" syndromes you will find on this website. The common presence of psychiatric problems is a good indication that brain dysfunction is a common factor involved with the ongoing state of illness in patients with these syndromes. It is also interesting to know that there is a strong link between the gut and the brain as both use many of the same chemical messengers. With this in mind it's easy to see how a disturbance in function of one, would cause symptoms in the other. Recent research into the brain-gut axis has shed a lot of light on this matter and will be discussed below.
What Causes IBS?
Although IBS is the most common diagnosis given by gastroenterologists (gut doctors), the causes of the illness aren't clear. In recent years however there has been an explosion of research into the causes of IBS and a number of distinct contributing factors have been identified as playing a major role in the syndrome. As a result of these findings many researchers are now proposing a "multicomponent disease model", meaning they suspect the illness is the result of a combination of factors acting together to bring about symptoms, rather than IBS having one single cause (1). The areas that have been identified through years of research as being involved with the illness are discussed below
Factors that may have a role in IBS include:
Neurological Dysfunction and Brain-Gut Interaction
Numerous studies have shown that serotonin exerts a wide range of effects on the intestines, most notably:
Recent studies have found increased levels of metabolites from this neurotransmitter in IBS patients (2). Indeed, the same studies have also shown that giving test subjects serotonin-like substances may trigger IBS symptoms (2). Other studies have shown abnormalities in the way serotonin acts in those with IBS (3). These abnormalities in serotonin levels and function may directly cause abnormalities in gut function by acting in the ways listed above, or they may alter the way the patient perceives sensations in the gut due to the strong connection between gut and brain. As a result of these findings, many new therapies that specifically act to normalize serotonin function are currently being tested. Some drugs treatments have shown promise with Tegaserod having good results in women with constipation predominant IBS and Alosetron performing well in women with diarrhea predominant IBS (3). Why these treatments only appear to be effective in women is so far unexplained.
Stress and Psychological Factors
Leaky Gut Syndrome
Food Sensitivities and Intolerance's
Food intolerances are also known to play a role in IBS. An intolerance is defined as a food triggering symptoms through a mechanism that does not involve the immune system (i.e. not an allergic reaction). Lactose intolerance is a common cause of gastrointestinal symptoms and is routinely tested for in IBS patients. Less well known is that fructose intolerance may also contribute to IBS. Fructose is the sugar mainly found in fruit and other plant foods. Research suggests that about one third of patients with IBS have fructose intolerance and that a low fructose diet leads to improvement in symptoms, particularly abdominal pain, belching, bloating, fullness, indigestion, and diarrhea (26).
Other than gluten, people with IBS often find that the following things exacerbate their symptoms:
More on Celiac disease
Links Between IBS and Other Environmentall Illnesses
As discussed above, IBS is strongly connected to leaky gut syndrome and gut dysbiosis, in the form of small intestine bacterial overgrowth (SIBO). There are also connections between IBS and other environmental illnesses that we cover on this website. IBS is often diagnosed in people who have also been diagnosed with chronic fatigue syndrome (CFS), fibromyalgia (FMS), Gulf war syndrome (GWS) and autism. As an example, 30-70% of fibromyalgia patients have concurrent IBS (18). Recent research has looked into this connection and started to discover possible reasons why IBS so often goes hand in hand with these other chronic illnesses.
One of the most well studied links is the involvement of SIBO in all of these illnesses, especially CFS and fibromyalgia. Just as SIBO has been found to be common in IBS patients, recent research has also found this to be the case with fibromyalgia and CFS (19, 20, 21). Researchers from the Burns and Allen Research Institute in Los Angeles published a study entitled "A link between irritable bowel syndrome and fibromyalgia may be related to findings on lactulose breath testing" (21). In it they describe their finding that SIBO is common in both IBS and fibromyalgia patients. Interestingly, they found that SIBO was more severe in fibromyalgia patients and the severity of the SIBO in individual patients correlated strongly with the severity of the pain they experienced. To speculate on this research, could it be possible that if the SIBO of those with only IBS were to get worse, they too would experience fibromyalgic pain? Only further research can answer that question.
Other published material makes the connection between IBS, CFS, fibromyalgia and autism suggesting that all are the result of the brain showing abnormal responses to stimuli (22). Further to this, just as the gut-brain link is thought to be important in IBS, so too is research demonstrating its importance, and that of serotonin function, in autistic disorders (23).
In a study of almost 12,000 Gulf war veterans, they were found to have a much higher incidence of IBS, as well as chronic fatigue syndrome (CFS) and multiple chemical sensitivity (MCS), as diagnosed by their physicians, than the general population. Studies have also shown that those with Gulf war syndrome have "visceral hypersensitivity similar to patients with the irritable bowel syndrome", meaning their intestines are more sensitive to normal stimuli, just as those of IBS patients are (25).
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|Last Updated on Saturday, 19 March 2011 18:24|