What Is Malabsorption Syndrome

Malabsorption syndrome is the inability of the small intestine to absorb adequate amounts of nutrients from the digested food.

  • Weight loss, chronic diarrhea, and passing of bulky stools which may have foul smell and light color, are the usual symptoms
  • Infections, certain surgeries, and disorders of the digestive tract, are the usual causes of malabsorption.
  • Presence of the characteristic symptoms of malabsorption, and stool tests showing the presence of fat, lead to diagnosis of the condition. Biopsy of the lining of the small intestine helps in confirming the diagnosis.
  • Malabsorption is treated according to the cause of the condition.

The small intestine is the main organ for digestion and absorption of nutrients from the food. If the assimilation of nutrients into the blood is disrupted by disorders which affect the normal process, it results in malabsorption and deficiency of those nutrients.

The digestion of food is aided by the digestive juices secreted by the stomach and the intestine. The digestive juices consist of stomach acids and digestive enzymes. Different substances in the digestive juices act on different types of food. If there is an insufficiency of any of the digestive enzymes, it results in the malabsorption of specific types of nutrients. The digestive enzyme lactase, necessary for the digestion and absorption of the complex lactose sugar contained in milk and other dairy products, is produced by the small intestine. Deficiency of the enzyme lactase results in the malabsorption of lactose sugar.

When the food reaching the stomach is not properly mixed with the digestive acids and the digestive enzymes, it may lead to incomplete digestion and malabsorption of nutrients. This type of malabsorption syndrome due to inadequate mixing is very common in people who have undergone surgery to remove a portion of the stomach.

Pancreas is an organ of the digestive system responsible for the production certain digestive enzymes. Due to diseases affecting the pancreas, the enzyme production may be decreased resulting in the malabsorption of certain substances from the food.  Inadequate bile production, excessive acid production by the stomach, or the proliferation of certain types of bacteria in the intestines, also may cause malabsorption.

The tissue lining the small intestine has small finger-like projections called villi and microvilli which increase the total surface area available for the absorption of nutrients into the blood. Injury to this lining can result in the malabsorption of a wide range of substances including, proteins, sugars, vitamins and essential minerals. When a portion of the small intestine is diseased or when it is surgically removed as part of treatments for digestive disorders, the area available for absorption of nutrients  become greatly reduced, resulting in malabsorption. When the length of the small intestine is reduced, food passes through it too quickly, not giving enough time for the absorption, causing a condition called short bowel syndrome.

Intestinal parasites such as worms and micro organisms, bacterial or viral infections, and certain drugs used to treat the infections, often interfere with absorption. Certain conditions like Crohn’s disease and celiac sprue also cause malabsorption. Inadequate blood supply, lymphomas causing blocks in the lymphatic system of the intestinal wall and alcohol consumption are some of the other causes for malabsorption.


Malabsorption can cause symptoms in two ways. The excessive presence of undigested and unabsorbed materials in the digestive tract is one of them. Deficiency disorders caused by insufficient absorption of specific substances constitute the other.

When fats are not broken down and absorbed by the small intestine, it results in a condition called steatorrhea, commonly known as fatty stools. The stool may be bulky and light in color with a foul smell. The sticky stool may remain stuck to the toilet bowl and be difficult to flush away or it may float in the water in the bowl. Bloating of the abdomen, excessive gas formation and explosive diarrhea may result from the malabsorption of sugars like lactose.

Malabsorption may result in the deficiency of a specific nutrient such as certain vitamins or proteins or a general nutritional deficiency. Weight loss is very common among people who have malabsorption. Other symptoms may depend on specific deficiencies; for example, edema, hair loss and dry skin caused by the deficiency of proteins.


Malabsorption is investigated when a person comes to the doctor with symptoms such as chronic diarrhea and significant weight loss without obvious reasons. Deficiency diseases also may be present. However, the symptoms of malabsorption may not be easily recognizable in older people.

The stool passed by a person having malabsorption usually contains undigested food particles and visible fat. Too much fat in the stool is an indication of inadequate bile production, a condition common in people with jaundice. Food passing through the digestive tract too quickly, without sufficient time for the digestive processes to act on it, results in incomplete digestion and presence of food particles in the stool. Testing of the stool in the laboratory may detect the presence of intestinal parasites interfering with the absorption of nutrients. The amount of fat in the stool is measured in the lab. If it is above 7grams per day in a three day’s collection of stool samples, malabsorption is confirmed. There are lab tests for malabsorption, specific to individual substances like Vitamin B12 or milk sugar lactose.

 An endoscopic procedure, in which a clipper-tipped endoscope is threaded down the digestive tract to reach the small intestine, helps collect a tissue sample from the lining of the intestine. The sample collected is tested for abnormalities that may be causing the malabsorption.

If malabsorption syndrome is suspected to be resulting from the inadequate secretion of pancreatic enzymes, pancreatic function tests are conducted. A thin tube passed into the small intestine draws out the digestive juice which contains the secretions of the pancreas as well. Testing of the ingredients of the collected fluid may show if pancreatic insufficiency is present. Sometimes a test, which involves swallowing a fixed quantity of a substance digestible by the pancreatic enzymes and then measuring the byproducts in the urine, helps in assessing the function of the pancreas.

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Yasser Elnahas

MD, PHD, Professor Of CardioVascular Surgery
Dr. Yasser Elnahas, Is an associate Professor of Cardiovascular Surgery. Dr. Elnahas was trained as a fellow At Texas Heart Institute And Mayo Clinic Foundation.Dr. Elnahas is dedicated to educating the general public about different disease conditions and simplifying the medical knowledge in an easy to understand terminology.

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