Lactose intolerance overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Lactose intolerance is the term used to describe a decline in the level of lactase, an enzyme needed for proper metabolization of lactose (a sugar that is a constituent of milk and other dairy products), in human beings.
Historical Perspective
The ancient Greek physician Hippocrates (460-370 B.C.) first noted gastrointestinal upset and skin problems in some who consumed milk. The condition was first recognized in the 1950s and 1960s when various organizations like the United Nations began to engage in systematic famine-relief efforts in countries outside Europe for the first time. Holzel et al (1959) and Durand (1959) produced two of the earliest studies of lactose intolerance.
Classification
There are three major types of lactose intolerance.[1] They are primary lactose intolerance, secondary lactose intolerance and congenital lactase deficiency.
Causes
Some causes of lactose intolerance are well known. Primary lactase deficiency is a condition that develops over time. After about age 2 the body begins to produce less lactase, though most people will not notice symptoms until they are much older. Secondary lactase deficiency occurs when injury to the small intestine or certain digestive diseases reduce the amount of lactase a person produces. These diseases include celiac disease, inflammatory bowel disease, and Crohn’s disease.
Epidemiology and Demographics
An estimated 70%[2] of adult humans are considered lactose intolerant, it is uncommon in healthy northern westerners and a few others groups.
References
- ↑ B. Heyman. Lactose Intolerance in Infants, Children, and Adolescents. PEDIATRICS Vol. 118 No. 3 September 2006, pp. 1279-1286 (doi:10.1542/peds.2006-1721)
- ↑ Kretchmer N. Lactose and lactase: a historical perspective. Gastroenterology, 1971;61, 805–813