Irritable Bowel Syndrome
What Is Irritable
Bowel Syndrome?
What Causes IBS?
What Are the Symptoms of IBS?
How Is IBS Diagnosed?
How Do Diet and Stress Affect IBS?
How Does a Good Diet Help IBS?
Can Medicines Relieve IBS Symptoms?
Is IBS Linked to Other Diseases?
Irritable Bowel Syndrome in Children
Additional Readings
Video References
What Is
Irritable Bowel Syndrome?
Irritable bowel syndrome (IBS) is a common disorder of the intestines
that leads to crampy pain, gassiness, bloating, and changes in bowel habits.
Some people with IBS have constipation (difficult or infrequent bowel
movements); others have diarrhea (frequent loose stools, often with an
urgent need to move the bowels); and some people experience both. Sometimes
the person with IBS has a crampy urge to move the bowels but cannot do
so.
Through the years, IBS has been called by many names--colitis,
mucous colitis, spastic colon, spastic bowel, and functional bowel disease.
Most of these terms are inaccurate. Colitis, for instance, means inflammation
of the large intestine (colon). IBS, however, does not cause inflammation
and should not be confused with another disorder, ulcerative colitis.
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. IBS causes a great deal of discomfort
and distress, but it does not cause permanent harm to the intestines and
does not lead to intestinal bleeding of the bowel or to a serious disease
such as cancer. Often IBS is just a mild annoyance, but for some people
it can be disabling. They may be unable to go to social events, to go
out to a job, or to travel even short distances. Most people with IBS,
however, are able to control their symptoms through medications prescribed
by their physicians, diet, and stress management.
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What Causes
IBS?
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.
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What Are
the Symptoms of IBS?
If you are concerned about IBS, it is important to realize that normal
bowel function varies from person to person. Normal bowel movements range
from as many as three stools a day to as few as three a week. A normal
movement is one that is formed but not hard, contains no blood, and is
passed without cramps or pain.
People with IBS, on the other hand, usually have crampy
abdominal pain with painful constipation or diarrhea. In some people,
constipation and diarrhea alternate. Sometimes people with IBS pass mucus
with their bowel movements. Bleeding, fever, weight loss, and persistent
severe pain are not symptoms of IBS but may indicate other problems.
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How Is IBS Diagnosed?
IBS usually is diagnosed after doctors exclude the presence of disease.
To get to that point, the doctor will take a complete medical history
that includes a careful description of symptoms. A physical examination
and laboratory tests will be done. A stool sample will be tested for evidence
of bleeding. The doctor also may do diagnostic procedures such as x-rays
or endoscopy (viewing the colon through a flexible tube inserted through
the anus) to find out if there is disease.
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How Do Diet and
Stress Affect IBS?
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.
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How Does
a Good Diet Help IBS?
For many people, eating a proper diet lessens IBS symptoms. Before changing
your diet, it is a good idea to keep a journal noting which foods seem
to cause distress. Discuss your findings with your doctor. You also may
want to consult a registered dietitian, who can help you make changes
in your diet. For instance, if dairy products cause your symptoms to flare
up, you can try eating less of those foods. Yogurt might be tolerated
better because it contains organisms that supply lactase, the enzyme needed
to digest lactose, the sugar found in milk products. Because dairy products
are an important source of calcium and other nutrients that your body
needs, be sure to get adequate nutrients in the foods that you substitute.
Dietary fiber may lessen IBS symptoms in many cases. Whole
grain breads and cereals, beans, fruits, and vegetables are good sources
of fiber. Consult your doctor before using an over-the-counter fiber supplement.
High-fiber diets keep the colon mildly distended, which may help to prevent
spasms from developing. Some forms of fiber also keep water in the stools,
thereby preventing hard stools that are difficult to pass. Doctors usually
recommend that you eat just enough fiber so that you have soft, easily
passed, and painless bowel movements. High-fiber diets may cause gas and
bloating, but within a few weeks, these symptoms often go away as your
body adjusts to the diet. Large meals can cause cramping and diarrhea
in people with IBS. Symptoms may be eased if you eat smaller meals more
often or just eat smaller portions. This should help, especially if your
meals are low in fat and high in carbohydrates such as pasta, rice, whole-grain
breads and cereals, fruits, and vegetables.
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Can Medicines
Relieve IBS Symptoms?
Your doctor may prescribe fiber supplements or occasional
laxatives if you are constipated. Some doctors prescribe drugs that control
colon muscle spasms, drugs that slow the movement of food through the
digestive system, tranquilizers, or antidepressant drugs, all of which
may relieve symptoms. It is important to follow the physician's instructions
when taking IBS medications--particularly laxatives, which can be habit
forming if not used carefully.
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Is IBS
Linked to Other Diseases?
IBS has not been shown to lead to any serious, organic diseases. No link
has been established between IBS and inflammatory bowel diseases such
as Crohn's disease or ulcerative colitis. IBS does not lead to cancer.
Some patients have a more severe form of IBS, and the pain and diarrhea
may cause them to withdraw from normal activities. These patients need
to work with their physicians to find the best combination of medicine,
diet, counseling, and support to control their symptoms.
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Irritable Bowel Syndrome in Children
View our page on Irritable Bowel Syndrome in Children for more details.Also, refer to Scanlon, D, Becnel, B. Wellness Book of IBS. New York: St. Martin's Press, 1989. Practical patient's guide to coping with IBS written by a registered dietitian. Available in libraries and bookstores.
Additional
Readings
- Scanlon, D, Becnel, B. Wellness Book of IBS. New York:
St. Martin's Press, 1989. Practical patient's guide to coping with IBS
written by a registered dietitian. Available in libraries and bookstores.
- Shimberg, E. Relief From IBS. New York: M. Evans and
Company, 1988. Practical book for patients offers information about
IBS symptoms, diet, treatment, and self-care. Available in libraries
and bookstores.
- Steinhart, MJ. Irritable bowel syndrome: How to relieve
symptoms enough to improve daily function. Postgraduate Medicine 1992;
91(6): 315-321. Article for primary care physicians includes information
about relief of IBS symptoms. Available in medical and university libraries.
- Thompson, WG. Gut reactions: Understanding symptoms
of the digestive tract. New York: Plenum Publishing Corp., 1989. Clear,
concise book by a digestive diseases specialist gives advice about diagnosis,
diet, and treatment of IBS. Available in libraries and bookstores.
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Video
References
Video: Irritable
Bowel Syndrome Tutorial - The National Library of Medicine
http://www.nlm.nih.gov/medlineplus/tutorials/irritablebowelsyndrome/htm/index.htm
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