performing the tests (seven days for aspirin and
NONSTEROIDAL ANTI-INFLAMMATORY DRUGS [NSAIDS]).
Women should do FOBT when they are not men-
struating.
SUBSTANCES THAT MAY ALTER FOBT RESULTSFalse-Positive Results False-Negative Results
red meat vitamin C supplements
cruciferous vegetables citrus fruits and juices
cantaloupe
Health-care professionals recommend FBOT
annually starting at age 45 for both men and
women as a screening for colorectal cancer. Doctors
also may request FBOT when they suspect condi-
tions that can cause GASTROINTESTINAL BLEEDINGand
when there is ANEMIAfor no apparent reason.
See also CANCER PREVENTION; COLONOSCOPY.
fiber and gastrointestinal health Fiber, the indi-
gestible residue of plant-based foods, adds bulk to
the gastrointestinal contents. This bulk helps stim-
ulate PERISTALSIS, the rhythmic MUSCLEcontractions
of the intestinal wall that move gastrointestinal
contents through the digestive process. In the
SMALL INTESTINE where digestive juices work to
break down food particles into molecules of NUTRI-
ENTS, the consistency fiber adds to the chyme (the
thick, liquid mixture the STOMACHsends to the
intestines) helps keep the food in the small intes-
tine long enough for complete digestion to take
place. In the COLON, fiber helps maintain more
fluid in the stool, keeping this digestive waste soft
enough to pass easily from the body during a
BOWEL MOVEMENT.
A number of studies suggest a diet high in fiber
and low in saturated fats measurably reduces the
risk for intestinal polyps as well as for COLORECTAL
CANCER. Good sources of dietary fiber include
fruits, vegetables, and whole grains and whole
grain products. Products such as methylcellulose
(Citrucel) and psyllium (Metamucil) can supple-
ment dietary fiber. Drinking plenty of water is also
important to keep the body hydrated, which
reduces the amount of water the colon extracts
from digestive waste.
See also CONSTIPATION; DIARRHEA; INTESTINAL POLYP;
NUTRITIONAL NEEDS.flatulence The clinical term for intestinal gas.
Flatulence indicates undigested food particles are
present in the COLON. Consuming large quantities
of indigestible fiber (such as with beans and other
legumes), eating too fast to thoroughly chew food
before swallowing, and eating a larger quantity of
food than the gastrointestinal tract can accommo-
date are common reasons for excessive amounts
of undigested food particles to make it to the
colon. BACTERIAnaturally present in the colon act
on these food particles. In addition to breaking
them down into nutrient molecules, the bacteria
also produce gas as a byproduct. These gases even-
tually make their way through the colon and
escape through the ANUS. The most common of
these are methane and hydrogen sulfide, which
give flatulence its characteristic odor. Excessive
flatulence often causes lower abdominal discom-
fort and cramping. It may occur withLACTOSE
INTOLERANCE, CARBOHYDRATE INTOLERANCE, and MAL-
ABSORPTIONand as a SIDE EFFECTof numerous med-
ications. The herbs peppermint, GINGER, and
CHAMOMILEreduce intestinal gas, as do products
containing simethicone, activated charcoal, or
enzymes that help break down cellulose (residual
fiber).
See also ANTACIDS.flatulence 45