Failure to Thrive
(FAYL-yoor too THRYV)
A condition that occurs when a baby does not grow normally.

Familial Polyposis
An inherited disease causing many polyps in the colon. The polyps often cause cancer.

Fats
One of the three main classes of food and a source of energy in the body. Bile dissolves fats, and enzymes break them down. This process moves fats into cells.

Fatty Liver
The buildup of fat in liver cells. The most common cause is alcoholism. Other causes include obesity, diabetes, and pregnancy. Also called steatosis.

Fecal Fat Test
A test to measure the body's ability to break down and absorb fat. The patient eats a fat-free diet for 2 to 3 days before the test and collects stool samples for examination.

Fecal Incontinence
Being unable to hold stool in the colon and rectum.

Fecal Occult Blood Test (FOBT)
A test to see whether there is blood in the stool that is not visible to the naked eye. A sample of stool is placed on a chemical strip that will change color if blood is present. Hidden blood in the stool is a common symptom of colorectal cancer.

Feces
Stool.

Fermentation
The process of bacteria breaking down undigested food and releasing alcohols, acids, and gases.

Fiber
A substance in foods that comes from plants. Fiber helps with digestion by keeping stool soft so that it moves smoothly through the colon. Soluble (SAWL-yoo-buhl) fiber dissolves in water. Soluble fiber is found in beans, fruit, and oat products. Insoluble (IN-sawl-yoo-buhl) fiber does not dissolve in water. Insoluble fiber is found in whole-grain products and vegetables.

Fistula
An abnormal passage between two organs or between an organ and the outside of the body. Caused when damaged tissues come into contact with each other and join together while healing.

Flatulence
Excessive gas in the stomach or intestine. May cause bloating.

Flatus
Gas passed through the rectum.

Foodborne Illness
An acute gastrointestinal infection caused by food that contains harmful bacteria. Symptoms include diarrhea, abdominal pain, fever, and chills. Also called food poisoning.

Fulminant Hepatic Failure (FHF)
Liver failure that occurs suddenly in a previously healthy person. The most common causes of FHF are acute hepatitis, acetaminophen overdose, and liver damage from prescription drugs.

Functional Disorders
Disorders such as irritable bowel syndrome. These conditions result from poor nerve and muscle function. Symptoms such as gas, pain, constipation, and diarrhea come back again and again, but there are no signs of disease or damage. Emotional stress can trigger symptoms. Also called motility disorders.

Fungus
A mold or yeast such as Candidiasis that may cause infection.