Causes of Irritable bowel syndrome


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Cause of Irritable bowel syndrome: The cause of IBS is not known, and as yet there is no cure. Doctors call it a functional disorder because there is no sign of disease when the colon is examined. 1

Triggers list for Irritable bowel syndrome: The list of triggers mentioned in source as possible causal factors for Irritable bowel syndrome includes:

Cause details for Irritable bowel syndrome: The colon, which is about 6 feet long, connects the small intestine with the rectum and anus. The major function of the colon is to absorb water and salts from digestive products that enter from the small intestine. Two quarts of liquid matter enter the colon from the small intestine each day. This material may remain there for several days until most of the fluid and salts are absorbed into the body. The stool then passes through the colon by a pattern of movements to the left side of the colon, where it is stored until a bowel movement occurs.

Colon motility (contraction of intestinal muscles and movement of its contents) is controlled by nerves and hormones and by electrical activity in the colon muscle. The electrical activity serves as a "pacemaker" similar to the mechanism that controls heart function.

Movements of the colon propel the contents slowly back and forth but mainly toward the rectum. A few times each day strong muscle contractions move down the colon pushing fecal material ahead of them. Some of these strong contractions result in a bowel movement.

Because doctors have been unable to find an organic cause, IBS often has been thought to be caused by emotional conflict or stress. While stress may worsen IBS symptoms, research suggests that other factors also are important. Researchers have found that the colon muscle of a person with IBS begins to spasm after only mild stimulation. The person with IBS seems to have a colon that is more sensitive and reactive than usual, so it responds strongly to stimuli that would not bother most people.

Ordinary events such as eating and distention from gas or other material in the colon can cause the colon to overreact in the person with IBS. Certain medicines and foods may trigger spasms in some people. Sometimes the spasm delays the passage of stool, leading to constipation. Chocolate, milk products, or large amounts of alcohol are frequent offenders. Caffeine causes loose stools in many people, but it is more likely to affect those with IBS. Researchers also have found that women with IBS may have more symptoms during their menstrual periods, suggesting that reproductive hormones can increase IBS symptoms. 1

IBS is not a disease. It's a functional disorder, which means that the bowel doesn't work as it should.

With IBS, the nerves and muscles in the bowel are extra-sensitive. For example, the muscles may contract too much when you eat. These contractions can cause cramping and diarrhea during or shortly after a meal. Or the nerves can be overly sensitive to the stretching of the bowel (because of gas, for example). Cramping or pain can result.2

Irritable bowel syndrome is not a disease. It is a functional disorder, which means that there is a problem in how the muscles in the intestines work. Irritable bowel syndrome is characterized by gas, abdominal pain, and diarrhea or constipation, or both. Although the syndrome can cause considerable pain and discomfort, it does not damage the digestive tract as diseases do. Also, irritable bowel syndrome does not lead to more serious digestive diseases later. 3

The colon absorbs water and salts from digested food after it has traveled from the stomach through the small intestine. The muscles of the colon contract (tighten or squeeze) and gradually move the material toward the rectum. Strong contractions then lead to a bowel movement. Colon contractions are controlled by nerves, hormones, and by electrical activity in the muscles.

Researchers have found that, for unknown reasons, the colons of people with IBS are more sensitive than usual, and react to things that would not bother other people. For example, the muscles may contract too much after eating. These contractions can cause cramping and diarrhea during or shortly after a meal. The nerves can be overly sensitive to the stretching of the bowel (because of gas, for example), causing cramping or pain. Diet and stress play a role in IBS for many people, causing symptoms or making them worse. 4

Triggers discussion for Irritable bowel syndrome: The potential for abnormal function of the colon is always present in people with IBS, but a trigger also must be present to cause symptoms. The most likely culprits seem to be diet and emotional stress. Many people report that their symptoms occur following a meal or when they are under stress. No one is sure why this happens, but scientists have some clues.

Eating causes contractions of the colon. Normally, this response may cause an urge to have a bowel movement within 30 to 60 minutes after a meal. In people with IBS, the urge may come sooner with cramps and diarrhea.

The strength of the response is often related to the number of calories in a meal and especially the amount of fat in a meal. Fat in any form (animal or vegetable) is a strong stimulus of colonic contractions after a meal. Many foods contain fat, especially meats of all kinds, poultry skin, whole milk, cream, cheese, butter, vegetable oil, margarine, shortening, avocados, and whipped toppings.

Stress also stimulates colonic spasm in people with IBS. This process is not completely understood, but scientists point out that the colon is controlled partly by the nervous system. Stress reduction (relaxation) training or counseling and support help relieve IBS symptoms in some people. However, doctors are quick to note that this does not mean IBS is the result of a personality disorder. IBS is at least partly a disorder of colon motility. 1

Emotional stress will not cause a person to develop IBS. But if you already have IBS, stress can trigger symptoms. In fact, the bowel can overreact to all sorts of things, including food, exercise, and hormones. 2

Foods that tend to cause symptoms include milk products, chocolate, alcohol, caffeine, carbonated drinks, and fatty foods. In some cases, simply eating a large meal will trigger symptoms. 2

Here are some foods that may cause symptoms:

  • Fatty foods like french fries
  • Milk products like cheese or ice cream
  • Chocolate
  • Alcohol
  • Caffeine (found in coffee and some sodas)
  • Carbonated drinks like soda
2

In women, IBS symptoms may be worse during their menstrual periods, so hormone changes may be involved. Sometimes IBS symptoms appear after another illness. 4

In people with IBS, diet and stress often seem to cause symptoms. Many people report that their symptoms occur after a meal or when they are under stress. No one is sure why this happens, but scientists have some clues.

Eating causes contractions or spasms of the colon. Normally, this response may cause an urge to have a bowel movement within 30 to 60 minutes after a meal. In people with IBS, the urge may come sooner with cramps and diarrhea. Contractions may be stronger after a large meal or a meal with a lot of fat in it. Many people with IBS learn to avoid certain foods, beverages, and medicines that seem to make their symptoms worse.

Stress can cause contractions of the colon in people with IBS. The reasons for this are not clear, but scientists point out that the colon is controlled partly by the nervous system. Learning relaxation methods and other ways to reduce stress can be helpful. Counseling and support help relieve IBS symptoms in many people. 4

Some foods that may cause symptoms include:

  • Fatty foods like french fries

  • Milk products like cheese or ice cream (especially in people who have trouble digesting lactose, or milk sugar)

  • Chocolate

  • Alcohol

  • Caffeine (found in coffee, tea, and some sodas)

  • Carbonated drinks like soda

  • Sorbitol, a sweetener found in dietetic foods and in some chewing gums

  • Gas-producing foods including beans and certain vegetables like broccoli or cabbage.

4

Underlying condition causes of Irritable bowel syndrome: The list of possible underlying conditions (see also Misdiagnosis of underlying causes of Irritable bowel syndrome) mentioned in various sources as possible causes of Irritable bowel syndrome includes:

Irritable bowel syndrome as a symptom: Conditions listing Irritable bowel syndrome as a symptom may also be potential underlying causes of Irritable bowel syndrome. The list of conditions listing Irritable bowel syndrome as a symptom in our database includes:

Causes of Irritable bowel syndrome: medical news summaries: The following medical news items are relevant to causes of Irritable bowel syndrome:

Related information for causes of Irritable bowel syndrome: Further relevant information on causes of Irritable bowel syndrome may be found in the risk factors for Irritable bowel syndrome and underlying causes of Irritable bowel syndrome.

Footnotes:
1. excerpt from Irritable Bowel Syndrome: NIDDK
2. excerpt from IBS: NIDDK
3. excerpt from Facts and Fallacies About Digestive Diseases: NIDDK
4. excerpt from Irritable Bowel Syndrome: NWHIC

Last revision: May 30, 2003

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