What is malabsorption?

Causes and Symptoms

The nutritive components of food—carbohydrates, protein, fats, vitamins, and minerals—must be digested in the gastrointestinal tract and absorbed into the circulatory system to be of use to the body. Malabsorption of these nutrients is caused by specific defects in any one of the many separate processes involved in the digestion and absorption of food. It is also the result of general impairment of the structure or function of the gastrointestinal tract.

Malabsorption leads to poor growth when it affects the uptake of any essential nutrient, which is one that must be obtained from the diet. It may cause diarrhea if one of the more abundant constituents of food is not absorbed; carbohydrate malabsorption will usually lead to a watery diarrhea, while protein and fat malabsorption will cause a foul-smelling diarrhea that is dark or whitish, respectively. Diarrhea itself may reduce the absorption of nutrients.

Cystic fibrosis
is one of the most common causes of malabsorption in children. The mucus accompanying this disease is secreted into the gastrointestinal tract; it is largely indigestible and can obstruct the passage of nutrients.

Treatment and Therapy

Treatment for malabsorption depends entirely on its cause. In the case of bacterial infections that affect intestinal function, treatment with appropriate antibiotics will return this function to normal. In celiac sprue, an intolerance to the gluten found in wheat and other grains that alters the absorptive surface of the intestines, the removal of gluten from the diet restores normal activity. Some specific defects can be cured by the elimination or replacement of the dietary constituent that is not well digested or absorbed. Incidence of celiac disease rose during the first decade of the twenty-first century. In other cases, no curative treatment is known, as with cystic fibrosis.

Perspective and Prospects

In 1825, William Beaumont, a US Army surgeon, was the first to study human digestion in the stomach. Since then, the processes of digestion and absorption have become well understood, as have many of the causes of acquired and inherited malabsorption. Effective treatment has been developed in all but the most intractable cases. It is hoped that progress in understanding the genetic basis for inherited malabsorption will lead to earlier and definitive identification of affected individuals and eventually to suitable therapies.

Bibliography

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Janowitz, Henry D. Indigestion: Living Better with Upper Intestinal Problems, from Heartburn to Ulcers and Gallstones. New York: Oxford University Press, 1994.

Mayo Clinic. Mayo Clinic on Digestive Health: Enjoy Better Digestion with Answers to More than Twelve Common Conditions. 2d ed. Rochester, Minn.: Author, 2004.

Peikin, Steven R. Gastrointestinal Health. Rev. ed. New York: Quill, 2001.

Sharon, Michael. Complete Nutrition: How to Live in Total Health. London: Prion, 2001.

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Wu George Y., Nathan Selsky, and Jane M. Grant-Kels. Atlas of Dermatological Manifestations of Gastrointestinal Disease. New York: Springer, 2013.