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Gastrointestinal Problems: Greasy, Bulky Stools

Gastrointestinal (GI) problems are the second most common set of issues caused by cystic fibrosis (CF), and frequent, greasy, bulky stools are one of the most common symptoms both in childhood and adulthood. These stools can smell bad and be difficult to pass, causing constipation.1

How does cystic fibrosis impact the GI tract?

The GI tract is essentially a long tube that runs from the mouth to the anus. It is responsible for turning the food you eat into nutrients that your body can use, and virtually the entire GI tract can be affected in people with CF. Greasy, bulky stools are a sign that your body is not absorbing nutrients, specifically fats, as it should.

That’s because in CF the thick mucus generated by the non-working CFTR protein clogs the ducts (tubes) leading in and out of the pancreas, liver, and intestines, prevents pancreatic enzymes from flowing into the intestines, and slows the movements that help food move through the system.

What is malabsorption?

When the GI tract does not have enough pancreatic enzymes to work as it should, it increases malabsorption, which means the body does not absorb fats, proteins, and carbohydrates properly. Steatorrhea is the term for the presence of excess fat in the stool due to trouble digesting fats. When fat is not used by the body, it is sent out in the stool, which tends to make it greasy, bulky and float in the toilet.

The greasy, bulky stools of malabsorption lead to malnutrition, trouble growing in children, and difficulty keeping weight on in adulthood.2

Prevention of greasy, bulky stools

A variety of therapies help reduce the malabsorption that causes greasy, bulky stools. Prevention also helps improve nutrition and reduces the painful or embarrassing side effects of poor digestion. Prevention usually includes a combination of actions, including:

  • Taking pancreatic enzymes
  • Eating more calorie-dense healthy food, such as cream instead of milk2,3
  • Increasing liquids, including water, electrolyte replacement drinks, juices, and coconut water2
  • Taking CF-specific vitamins that contain fat-soluble vitamins A, D, E and K, and iron and zinc
  • Regular exercise since it is good for the digestion and the lungs
  • If taking antibiotics, eat probiotic-rich foods such as yogurt kefir, kombucha, salt-cured sour pickles, or probiotic pills

If treatment becomes necessary, it is called a “clean out.” The person is given polyethylene glycol (PEG) and large amounts of fluids until the intestines are clear.

What is distal intestinal obstruction syndrome (DIOS)?

DIOS, or distal intestinal obstruction syndrome, is a serious GI complication of CF. DIOS can cause the stools to totally block the intestines. This can lead to a bowel perforation that allows the intestinal contents to lead into the abdominal cavity. Bowel perforation requires emergency surgery.

Written by: Jessica Johns Pool | Last reviewed: September 2019
  1. Medscape. Cystic Fibrosis Clinical Presentation. Available at: https://emedicine.medscape.com/article/1001602-clinical. Accessed 4/30/2019.
  2. Dennett C. MNT in Cystic Fibrosis Care — What RDs Need to Know. Today's Dietitian. April 2017. Vol. 19, No. 4, p. 44.
  3. Cystic Fibrosis Foundation. Introduction to CF. Available at: https://www.cff.org/intro-to-CF.pdf. Accessed on 4/30/2019.