What is Lactose Intolerance?
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What is Lactose Intolerance?
The main sugar found in milk is lactose and is actually made up of two sugar molecules bound together (a di-saccharide). The body can't absorb lactose and it must be broken down into the two sugar molecules (mono-saccharides) glucose and galactose. Many people lack the enzyme lactase that the body uses to break down lactose, so the "milk sugar" is not absorbed and passes from the small intestine to the colon.
The problem is that the bacteria living in your large intestine love lactose and break it down causing many unpleasant effects. We think of these bacteria as the "good guys" (and they are) but in the process of using the lactose they create lactic acid and other chemicals. Those substances are what causes abdominal discomfort.
Who is Lactose Intolerant?
Lots of people. Most of us begin to lose the ability to make the lactase enzyme after being weaned. It is those of mostly Northern European and Scandinavian descent who are still able to make the lactase enzyme well into adulthood. The theory is that those people who did tolerate lactose in an environment where cows were a main source of nutrition survived better and thus passed on the genes for making lactase more successfully.
This means that most other populations not farming such animals are lactose intolerant by adulthood. Here's a rough breakdown:
80% of those of Asian descent
79% of Native Americans
75% of those of African descent
51% of Hispanic Americans
21% of Caucasians
I've just added more information about Lactose Intolerance to the Dr. Gourmet website, including When people become lactose intolerant, Where you can find out if you are, and a handy downloadable guide to the amount of lactose in some common dairy foods.
First posted: May 2, 2007
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