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 ulcerative
colitis, which is a more serious disorder.
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 afraid 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 diet, stress management, and sometimes
with medications prescribed by their physicians.
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
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 an overreaction 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
What Are the Symptoms of 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 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, and may indicate other problems.
How is IBS Diagnosed?
IBS usually is diagnosed after doctors exclude more serious
organic diseases. The doctor will take a complete medical history
that includes a careful description of symptoms. A physical examination
and laboratory test 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 lower GI endoscopy (viewing the colon through
a flexible tube) to find out if there is organic disease.
How Does Diet and Stress Affect IBS?
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 and
may be associated with pain, 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. 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 spasms in people with IBS. This
process is not completely understood, but scientists point out
that the colon is controlled partly by the nervous system. Mental
health counseling and stress reduction (relaxation training) can
help relieve the symptoms of IBS. 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 fibers so that you have soft, easily passed, 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.
Can Medicines Relieve IBS Symptoms?
There is no standard way of treating IBS. Your doctor may prescribe
over-the-counter fiber supplements or occasional laxatives if
you are constipated, or may prescribe over-the-counter anti-diarrheal
medicine if you are suffering from diarrhea. Your doctor may also
prescribe other treatment programs to help relieve your symptoms
and reduce the effects of IBS on your lifestyle.
How is IBS Linked to More Serious Problems?
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 fear of pain and diarrhea may cause them
to withdraw from normal activities. In such cases, doctors may
recommend mental health counseling.