Almost 200 different conditions or diseases are associated with malabsorption. All impair the digestion, absorption or transport of nutrients into the bloodstream from the small intestine. Some of these conditions cause malabsorption in addition to other problems, whereas others primarily involve malabsorption and its complications.  

Conditions that primarily involve malabsorption include:

• Lactose intolerance. An inability to digest dairy products containing lactose due to the lack of the lactase enzyme. As many as 50 million Americans are lactose intolerant, according to the National Institutes of Health (NIH). Related conditions include intolerances to bovine lactalbumin (a protein found in cow’s milk) and soy milk protein, which can also cause malabsorption.
  
  
• Short bowel syndrome. Malabsorption that occurs as the result of lost surface area within the small intestine. This is often caused by conditions such as Crohn's disease or necrotizing enterocolitis (in infants), where diseased sections of the small intestine are removed and subsequently limit nutrient absorption. It may also occur after bariatric surgery, which is performed in an effort to lose weight.
  
  
• Celiac disease. An inherited sensitivity to the protein gluten (found in wheat, barley, rye and oats) that causes damage to the small intestine and interferes with nutrient absorption. It is estimated that approximately 2 million Americans have celiac disease, according to the NIH.
  
  
• Tropical sprue. A disorder caused by an overgrowth of bacteria that results in abnormalities of the small intestine, leading to malabsorption. It typically occurs in people who live or visit tropical or subtropical areas (such as the Caribbean, southern India and Southeast Asia).
  
  
• Whipple disease. This rare, infectious disease injures the lining of the small intestine. Sores and damage to the intestinal wall interfere with the absorption of carbohydrates or fats. Whipple disease may be treated with a prolonged course of antibiotics for up to a year, although relapse is common. If left untreated, it can be fatal.
  
  
• Intestinal lymphangiectasia. A condition in which the lymph nodes in the small intestine become enlarged and obstructed, causing the malabsorption of fats and protein. This condition primarily affects children and young adults.

Other conditions that include malabsorption in addition to other problems include:

• Cystic fibrosis. A hereditary disease that causes the buildup of thick, sticky mucus in the lungs and digestive tract. Mucus may obstruct the pancreas, intestines and bile ducts, as well as the air passages in the lungs. This can result in life-threatening lung infections and serious digestive problems, including malabsorption. According to the Cystic Fibrosis Foundation, the disease affects 30,000 children and adults in the United States.
  
  
• Chronic pancreatitis. Persistent, ongoing inflammation and scarring of the pancreas. It occurs when digestive enzymes attack the pancreas instead of breaking down food in the small intestine. In cases of chronic pancreatitis, the pancreas may eventually stop producing these enzymes, which can lead to malabsorption. Many cases of chronic pancreatitis appear to be caused by alcoholism.
  
  
• Crohn's disease. Inflammation and sores (ulcers) that occur in the lining of the digestive tract. When it occurs in the small intestine, this irritation can limit the small intestine’s ability to absorb nutrients from food. Crohn’s disease may also cause perforation or obstruction of the intestinal wall, which can require surgery. About 500,000 Americans have CD, according to the Crohn's & Colitis Foundation of America.
  
  
• Zollinger-Ellison syndrome. A rare condition in which tumors develop in the pancreas and the small intestine’s duodenum. These tumors stimulate excessive stomach acid, which can damage the lining of the stomach and small intestine, leading to malabsorption.
  
  
• Shwachman-Diamond syndrome. A rare condition that affects the pancreas, bone marrow and skeleton. Failure of the pancreas to produce digestive enzymes in people with this condition can lead to malabsorption.
  
  
• Other conditions. There are many other conditions and diseases that can also cause malabsorption, including:
  
  
• • Infections (e.g., by parasites such as giardia lamblia and hookworm)
    
    
  • Cancers (e.g., lymphoma, pancreatic)
    
    
  • Immune system diseases (e.g., AIDS)