IBS Questions & Answers
The cause of IBS is not completely understood. There are possible factors like genetic factors and early adverse life experiences (e.g., infection, trauma) that can predispose someone to get IBS.
The symptoms appear to result from disturbances in colonic motility (muscle contractions) and increased sensitivity to food, gas, or stool in the bowel.
Finally, there is a tendency for the bowel to be overly reactive to various factors: eating, stress, emotional arousal, gastrointestinal infections, menstrual period, or gaseous distension, which can amplify or bring about the symptoms.
The altered patterns of colonic motility and sensation appear to be due to disruptions in the communication between the brain and gut. This is known as the brain-gut axis.
These bi-directional interactions between the brain and gut are important in maintaining normal bowel function. They also respond to any potential disturbance or stressor. However, in IBS, normal regulation of the brain-gut interactions become altered, which leads to changes in motility, sensation, and secretion within the bowel.
There are a number of factors that may play a role in the alteration in the brain-gut axis. These factors include:
- a genetic predisposition (e.g., family history of IBS) to developing IBS,
- an intestinal infection prior to symptom onset,
- chronic stressful life events, or other psychosocial factors.
Some of these factors may be more relevant in one individual with IBS, while other factors may be more important in another.
Does bacteria overgrowth cause IBS?
There are over a hundred trillion bacteria in the bowel. These bacteria help break down the food we eat and regulate bowel function including motility, sensation, and immune function.
However, there has been relatively recent evidence that some people with IBS have an increased amount of bacteria in the bowel (referred to as small intestinal bacterial overgrowth). Some of these people have been shown to experience an improvement in their symptoms with antibiotic treatment and eradication of the bacterial overgrowth. However, these studies should be interpreted with caution. The amount of bacteria in the bowel is difficult to measure. Glucose or lactulose breath tests are performed to measure small intestinal bacterial overgrowth.
While some studies demonstrate that small intestinal bacterial overgrowth is more common in IBS patients compared to persons without IBS, other studies do not. Moreover, some studies show no increase in bacterial overgrowth in people with IBS compared to otherwise healthy persons. More studies are needed to determine if this is a true association and the mechanisms by which bacterial overgrowth may cause symptoms of IBS.
There is also increasing evidence to suggest that it is not an overgrowth of the bacteria but an alteration in the types of bacteria – a shift from “good” to “bad” bacteria – that may produce IBS in some people.
Treatment for small intestinal bacterial overgrowth or possibly this altered bacterial composition is antibiotics. There are recent studies to support that some IBS patients experience an improvement of their symptoms with antibiotic treatment (see “How is IBS treated?” below). It is advisable to discuss this further with your doctor. Read more about IBS and Gut Flora
The impact of IBS varies with each person. For some people, IBS causes symptoms that are manageable and/or mild, and do not interfere with daily activities. For others, IBS may severely reduce their quality of life.
IBS can cause enough discomfort to alter daily activities and performance. This is the case mainly in those with more severe bowel symptoms and those with non-bowel symptoms, such as fatigue, low energy, or sleep and sexual disturbances.
IBS is a longlasting, or chronic, condition. Symptom episodes are often unpredictable and may have disabling effects. For many, treatments are minimally effective and the nature of the symptoms can lead to social stigma and isolation.
However, IBS is a benign disorder in that there are no long-term organic complications. People with IBS are no more likely to develop ulcerative colitis or cancer than other persons, and have no greater need of preventive checkups than other people.
The prevalence of IBS, that is the proportion of people with IBS within a population at a point in time, remains fairly stable. Over time, some people with IBS will no longer have symptoms (symptoms go into remission), while new people will develop IBS. It has been established that each year, about 10% of IBS patients get better. This suggests that most people with IBS will eventually get better, but this is not true for every person.
In cases where life-stress is an important and relevant factor, which impacts symptoms, IBS is less likely to go into remission until the stressor is resolved. Sometimes a life altering change (e.g., in lifestyle, job) may lead to complete recovery. In many cases, however, stress does not seem to be a contributory factor.
Is IBS colitis?
In the past, many people, including doctors, have mistakenly used the term “colitis” to mean “IBS,” which has led to much confusion. IBS was once called “spastic colitis.” Colitis is a medical term, which refers to an inflammation of the lining of the large bowel (the colonic mucosa).
Infections are a common cause of colitis. Inflammatory bowel diseases, such as Crohn’s disease or ulcerative colitis, can also produce colitis and in these cases there is clear evidence for ulcers or other changes of inflammation when seen during endoscopy or by an x-ray.
This is not the case in IBS. There is usually no obvious infection or inflammation seen by these methods, though microscopic changes may exist. For example in “post-infectious” IBS, individuals who had no previous IBS symptoms develop them after a gastrointestinal infection (e.g., food poisoning) even after the infection has cleared. In these cases there may be microscopic signs of changes in the immune cells of the colonic lining.
This condition is more likely to occur in women, those with a severe gastrointestinal infection, and those with a chronic stressor at the time of the illness. Less than one-third of patients with IBS have a history of a gastrointestinal infection that preceded the onset of their IBS symptoms.
As noted, some people with post-infectious IBS and even some who have IBS without an earlier infection have microscopic evidence of increased immune activity in the lining of the colon (less than in the previously mentioned “microscopic colitis”). However, more studies are needed to determine if these immune changes are related to IBS symptoms, and if reversing these changes will relieve bowel symptoms. Read more about Post-infectious IBS
What causes bloating and gas?
Bloating is a common symptom in IBS. It is usually described by people as a feeling of fullness or heaviness in the belly. It may be associated with visible abdominal distension in which the belly appears swollen.
The cause of bloating is not well understood. Many factors may be involved, such as the increased intake of gas-forming foods, slowed transit and evacuation of gas through the bowel, and increased sensitivity to food, gas, and other bowel contents.
The abdominal distension is likely due to a reflex relaxation of the muscle of the abdominal wall and tightening of the diaphragm (the muscle that separates the chest from the abdomen and helps with breathing). This results in distension of the belly.
When tested, people with IBS do not actually produce more gas than those who do not have irritable bowel symptoms, unless they eat a large amount of gas-forming foods. However, IBS patients do appear to be more sensitive to the effects of normal amounts of gas.
They may also have slowed transit of gas through the intestine, leading to more retention of gas. They seem to have difficulties passing the gas that is present. Read more about Controlling Gas
Bowel function appears to be influenced by changes in the level of female hormones. Symptoms can become worse at certain times of the cycle, particularly at the time of menstrual periods. While both healthy women and women with IBS report a higher prevalence of gastrointestinal symptoms, such as pain and bloating, just prior and at the time of menstrual periods, it is reported as more intense in women with IBS.
This occurrence can sometimes make it difficult for the patient, as well as the physician, to determine whether she is having a gynecological problem (e.g., endometriosis or other pelvic pain condition) or a gastrointestinal problem. It is important for the patient, as well as the physician, to realize that sometimes both possibilities must be explored.
How do I find an appropriate health care provider?
There are no rules. In general, a good physician facilitates effective communication with the patient, which is the foundation for successful management of IBS. However, not all physicians have an understanding of how to treat patients with IBS.
If your physician is not meeting your needs, find one who can meet your needs. IBS is very common, and talking with your friends or coworkers may help you in finding a physician. Organizations such as the International Foundation for Functional Gastrointestinal Disorders (IFFGD) can also help you find an appropriate health care provider.
You should have a physician who is interested in you and has helped you to identify factors that seem to be contributing to your IBS symptoms. If you are interested in being referred to another health care provider, such as a physician with expertise in IBS, a therapist for behavioral or psychological treatment, or an alternative medicine provider, you should explain this to your physician and an appropriate referral should be forthcoming. Read more about Working with your Physician