Maldigestion and malabsorption syndromes are conditions that result in abnormalities in the digestion of food or in the intestinal absorption of nutrients into the bloodstream. These conditions often occur together.
In order for the body to use food, it must be chemically broken down into smaller compounds and then absorbed from the intestine into the bloodstream. If maldigestion occurs, the food a person eats is not broken down enough for the intestine to absorb it. If malabsorption occurs, the food is correctly digested, but abnormalities in the intestine prevent its absorption. As a result, the body does not get all the nutrients it needs; undigested or unabsorbed nutrients are lost in feces * . Maldigestion and malabsorption can occur with proteins, fats, carbohydrates (sugars and starches), and any of the vitamins or minerals the body needs. Often more than one type of nutrient is affected.
Many different diseases can cause malabsorption of various nutrients. The most common disease causing malabsorption is celiac disease, also called celiac sprue or gluten-sensitive enteropathy. As many as 1 in 141 Americans has celiac disease, although most remain undiagnosed. Celiac disease affects children and adults in all parts of the world and is more common in Caucasians and females. People with celiac disease cannot tolerate gluten, a protein found in wheat, rye, and barley. When people with celiac disease eat food containing gluten, their immune system * responds by causing the cells lining the wall of the small intestine to become inflamed. Over time, the inflammation * damages these cells so that they can no longer absorb a normal amount of nutrients.
The second most common cause of maldigestion and malabsorption is cystic fibrosis. This complex inherited disease involves the lungs, pancreas * , liver, and intestines. One aspect of the disease is that the pancreas does not produce enough digestive enzymes * (a problem of maldigestion), and abnormal chemistry of the intestines prevents normal absorption of nutrients.
Lactose maldigestion is a condition in which the cells lining the small intestine do not produce the enzyme lactase that is needed to digest the sugar lactose found in cow's milk. According to the National Institute of Diabetes and Digestive and Kidney Diseases, between 30 and 50 million American adults are lactose intolerant; these people may produce some lactase and can consume small amounts of dairy products, but they do not produce enough of the enzyme to digest the quantity of dairy products found in the standard American diet.
Other conditions and diseases that cause malabsorption include short bowel syndrome, Crohn's disease, and some weight control surgeries (bariatric surgeries) that shorten the intestine. AIDS * can also cause malabsorption of nutrients, as can diseases of the pancreas, including pancreatitis and pancreatic cancer. Infection with certain intestinal parasites * can interfere with the absorption of food. Certain drugs may also interfere with absorption of specific nutrients for as long as the drug is taken. Absorption normally improves after the drug is stopped.
Regardless of the cause, malabsorption and maldigestion syndromes produce somewhat similar symptoms. The most common symptoms are a bloated abdomen (stomach); chronic * diarrhea; passing a great deal of gas; bulky, bad-smelling stools; excessive fat in the stool (a condition called steatorrhea; stool often floats in the toilet because fat is lighter than water); weight loss; anemia * ; general weakness; fatigue; and fluid retention. Infants and young children gain little weight and do not reach developmental milestones at the times expected, a condition called failure to thrive.
Treatment depends on the cause of the syndrome. Eliminating gluten from the diet helps people with celiac disease. Limiting or eliminating dairy products helps people who are lactose intolerant. Some low-lactose and lactose-reduced products are available in the supermarket. Lactase, the enzyme that breaks down lactose so that it can be absorbed, can be eaten as a digestive aid. People with cystic fibrosis * are given supplemental pancreatic enzymes to aid digestion. Based on the specific nutrient deficiencies, people with malabsorption syndrome are given supplements of various vitamins and minerals, and the amount of calories in their diet may be increased. Malabsorption syndromes usually require life-long dietary adjustments and monitoring. Complications frequently arise based on deficiencies in specific vitamins and minerals.
See also Celiac Disease • Cystic Fibrosis
Bower, Sylvia Llewelyn, and Mary Kay Sharrett. Celiac Disease: A Guide to Living with Gluten Intolerance. 2nd ed. New York: Demos Health, 2014.
Thompson, Helen. “An Evolutionary Whodunit: How Did Humans Develop Lactose Tolerance?” NPR. December 28, 2012. http://www.npr.org/sections/thesalt/2012/12/27/168144785/an-evolutionary-whodunit-how-did-humans-develop-lactose-tolerance (accessed April 7, 2016).
MedlinePlus. “Lactose Intolerance.” U.S. National Library of Medicine, National Institutes of Health. https://www.nlm.nih.gov/medlineplus/lactoseintolerance.html (accessed April 7, 2016).
Merck Manual: Consumer Version. “Malabsorption.” http://www.merckmanuals.com/home/digestive-disorders/malabsorption/ (accessed April 7, 2016).
National Institute of Diabetes and Digestive and Kidney Diseases. “Celiac Disease.” (accessed April 7, 2016).
Celiac Disease Foundation. 20350 Ventura Blvd., Suite 240, Woodland Hills, CA 91364. Telephone: 818-716-1513. Website: http://celiac.org (accessed April 7, 2016).
Cystic Fibrosis Foundation. 6931 Arlington Rd., 2nd Floor, Bethesda, MD 20814. Telephone: 301-951-4422. Website: http://www.cff.org (accessed April 7, 2016).
National Institute of Diabetes and Digestive and Kidney Diseases. 2 Information Way, Bethesda, MD 20892. Telephone: 301-496-3583. Website: http://www.niddk.nih.gov (accessed April 7, 2016).
* feces (FEE-seez) is the excreted waste from the gastrointestinal tract.
* immune system (im-YOON SIStem) is the system of the body composed of specialized cells and the substances they produce that helps protect the body against disease-causing germs.
* inflammation (in-fla-MAY-shun) is the body's reaction to irritation, infection, or injury that often involves swelling, pain, redness, and warmth.
* pancreas (PAN-kree-us) is the gland located behind the stomach that produces enzymes and hormones necessary for digestion and metabolism.
* enzymes (EN-zimes) are proteins that help speed up a chemical reaction in a cell or organism.
* AIDS (or Acquired Immunodeficiency [ih-myoo-no-dih-FIH-shen-see] Syndrome) is an infection that severely weakens the immune system; it is caused by the human immunodeficiency virus (HIV).
* parasites (PAIR-uh-sites) are organisms such as a protozoa (one-celled animals), worms, or insects that must live on or inside a human or other organism to survive. An animal or plant harboring a parasite is called its host. Parasites live at the expense of the host and may cause illness. The adjectival form is parasitic.
* chronic (KRAH-nik) means lasting a long time or recurring frequently.
* anemia (uh-NEE-me-uh) is a blood condition in which there is a decreased hemoglobin in the blood and, usually, fewer than normal numbers of red blood cells.
* triglycerides (try-GLISS-eh-rides) are a type of fatty substances found in the blood.
* endoscopy (en-DOS-ko-pee) is a type of diagnostic test in which a lighted tube-like instrument is inserted into a part of the body.
* biopsy (BI-op-see) is a test in which a small sample of skin or other body tissue is removed and examined for signs of disease.
* cystic fibrosis (SIS-tik fy-BRO-sis) is a disease that causes the body to produce thick mucus that clogs passages in many of the body's organs, including the lungs.