Malabsorption is the term used to describe an inability to absorb nutrients. This dysfunction can occur at any point in the process of digestion or the transport of nutrients. A variety of different diseases and causes can interfere with cholesterol absorption. However, many cholesterol malabsorption diseases also affect the absorption of other dietary fats and interfere with the body's ability to digest the fat-soluble vitamins (A, D, E and K).
Chylomicron Retention Disease
When cholesterol is digested, it is broken down and surrounded by a protein layer. The resulting lipoprotein is called a chylomicron. Since cholesterol is not water soluble, the only way it can be transported through the body is in the form of a chylomicron. Chylomicron retention disease is a rare disorder that prevents the chylomicrons from being transported, so the cholesterol can't be absorbed.
Intestinal Lymphangiectasia
Intestinal lymphangiectasia causes an obstruction of the lymphatic system in the small intestine. It can be inherited or acquired from disorders such as pancreatitis or tumors. As it impairs the drainage of the lymph, it also interferes with absorption of chylomicrons and results in malabsorption of cholesterol.
Insufficient Digestive Agents
The absorption of cholesterol during digestion requires enzymes from the pancreas and bile acids from the liver. Any disease that interferes with these agents will subsequently inhibit the absorption of cholesterol. Pancreatitis or pancreatic tumors may prevent the pancreas from secreting sufficient enzymes. Cholestasis is any condition that blocks the flow of bile from the liver. Biliary atresia is an inherited disease that causes blockage of the tubes that deliver bile from the liver to the small intestine. Cirrhosis can reduce the production of bile. Too much bacteria, called bacterial overgrowth syndrome, results in a breakdown of bile salts, which limits the absorption of cholesterol.
Abnormal Intestinal Lining
The small intestine is lined with structures called villi, which are fingerlike projections designed to increase the surface area for absorption. Because the absorption of most nutrients occurs in the small intestine, diseases that damage the lining result in malabsorption of all nutrients, including cholesterol. Celiac is an inherited disease that causes your body to treat gluten (a protein in wheat, rye and barley) as though it is poisonous. The response from the immune system damages the lining of your small intestine and prevents absorption of nutrients including cholesterol. Whipple's disease is an extremely rare bacterial infection that also harms the lining of the intestine.
Blind Loop Syndrome
This condition is a blockage of the intestine in which the affected area forms a "blind loop." The loop blocks or slows down the flow of digested food. The result is an overgrowth of bacteria that interferes with cholesterol absorption. Also, according to the Merck Manual, when the intestine is blocked by a blind loop, bile salts become ineffective, resulting in poor absorption of fat and fat-soluble vitamins.
Zollinger-Ellison Syndrome
Zollinger-Ellison syndrome is caused by tumors located in the pancreas and small intestine. The tumors produce the hormone gastrin, which causes overproduction of stomach acid. This increased acidity inhibits digestion and absorption of cholesterol and dietary fats.
