The challenge of this diet is twofold. First, constipa-
tion and diarrhea are opposite in their effect, yet they
can appear in the same individual as part of the same
disorder. Constipation occurs when food stays in the
large intestine (colon) too long. Too muchwateris
reabsorbed into the body, and the stool (waste) in the
large intestine becomes hard, dry, and difficult or
painful to eliminate. With diarrhea, food moves too
quickly through the large intestine. Not enough water
is reabsorbed. Stools are loose and watery, and the
individual may feel extreme urgency to have a bowel
movement.
The second challenge to this diet is that individu-
als with IBS may respond to the same food in different
ways. The IBS diet is not a list of ‘‘must eat‘‘ and ‘‘must
not eat’’ foods, but rather a group of suggested foods
that the individual must personalize through trial and
error. Keeping a food journal often helps the person
with IBS to pinpoint which foods are beneficial and
which worsen symptoms.
High-fiber/low-fat IBS diet
Dietaryfiberis the collective name for a group of
indigestible carbohydrate-based compounds found in
plants. They are the materials that give the plant
rigidity and structure. The IBS diet is a high fiber/
low fat diet. The role of fiber is crucial in controlling
the quality of stool in the colon, while reducing the
consumption of fat is both healthful and avoids coun-
teracting the actions of fiber. Fiber is also called
roughage or bulk.
Two types of fiber are important to human health,
insoluble fiber and soluble fiber. Insoluble fiber is fiber
that moves through the digestive system essentially
unchanged. It is not digested, and it does not provide
energy (calories). What fiber does is provide bulk to
stool that helps it move through the large intestine. It
also traps water, which helps the stool remain soft and
easy to eliminate. In people with diarrhea, it can help
trap excess water.
Studies find that the average American eats only
5–14 grams of fiber daily, but the recommended
amounts are much higher. The United States Institute
of Medicine (IOM) of the National Academy of Sci-
ences has issued the following daily Recommended
Dietary Intakes (RDIs) for fiber.
men age 50 and younger: 38 grams
women age 50 and younger: 25 grams
men age 51 and older: 30 grams
women age 51 and older: 21 grams
children: 5 grams plus at least one gram for every
year of age
To follow the IBS diet, individuals should gradu-
ally increase their consumption of fiber to meet or
exceed the RDI. Foods that are high in insoluble
fiber include:
whole grains and foods made of whole grains, such as
whole wheat bread and whole wheat pasta, couscous,
or bulgur
bran and bran breakfast cereals
brown rice
carrots
cucumbers
Soluble fiber dissolves in water to form a gel-like
substance. This gel helps keep stool soft. Good sources
of insoluble fiber include:
oatmeal and foods made with oats
foods such as chili or split pea soup that contain
dried beans and peas
lentils
apples
pears
citrus fruits
The total amount of fiber per serving must be
listed on food labels in the United States. In 2007,
regulations were under consideration that that would
require soluble dietary fiber to be listed separately. A
good list of high-fiber foods can be found at<http://
http://www.gicare.pated/edtgs01.htm>. Most foods that are
high in fiber are naturally low in fat.
People who have trouble consuming enough fiber
and are still having difficulty with IBS symptoms can
ask their doctor about bulk-forming or fiber supple-
ment laxatives. These supplements are quite safe,
although they should not be used for long periods
unless directed by a doctor because the colon will
become dependent on them to move stool. Some com-
mon brand names of fiber-supplement laxatives are
Metamucil, Citrocel, Fiberall, Konsyl, and Serutan.KEY TERMS
Gastroenterologist—a physician who specializes
in diseases and disorders of the digestive system.
Type 2 diabetes—sometime called adult-onset dia-
betes, this disease prevents the body from properly
using glucose (sugar), but can often be controlled
with diet and exercise.Irritable bowel syndrome diet