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
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
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
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.
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.
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.
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
minutes 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.
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
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
Can Medicines Relieve IBS Symptoms?
There is no standard way of treating IBS. 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, or tranquilizers, all of which may
relieve symptoms. Antidepressant drugs also are used sometimes
in patients who are depressed. It is important to follow the
physician's instructions when taking IBS medications -
particularly laxatives, which can be habit forming if not used
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.