| 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.
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.
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 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 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.
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. In 2000, the U.S. Food and Drug Administration approved
alosetron hydrochloride to treat IBS in women. Alosetron slows
intestinal movement and may reduce nerve problems that could be
contributing to IBS. Refer to the Medication
Guide from the FDA for information on the potential risks of
alosetron.
It is important to follow the
physician's instructions when taking IBS medications--particularly
laxatives, which can be habit forming if not used carefully.
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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