Dear Dr. B: I have been told I am lactose intolerant. What does that mean? How did I get the problem? What can I do about it? What is my prognosis?
Answer: Lactose is a natural sugar found in milk and dairy products. Lactose intolerance means inability to digest lactose. This inability results from a shortage of the enzyme lactase, which is normally produced by the cells that line the small intestine.
Function of lactase is to break down milk sugar into simpler forms that can then be absorbed into the bloodstream. Lactose is broken down in the intestine by lactase to glucose and galactose. These simple sugars are easily absorbed through the intestinal wall and enter the blood stream to be transported to the liver. Galactose is further broken down in the liver into glucose.
Lactose intolerance commonly develops after adolescence. It is more common in certain ethnic groups. Information obtained from the internet suggests that between 30 and 50 million Americans are lactose intolerant.
Certain ethnic and racial populations are more widely affected than others. As many as 75 percent of all African Americans and American Indians and 90 percent of Asian Americans are lactose intolerant. The condition is least common among persons of northern European descent.
Medical literature says that at birth large amount of lactase may be present in the intestine. But as the child grows the level of lactase may fall and by adolescence the level may be low enough that the milk can no longer be digested.
Lactase deficiency may be congenital. Or the deficiency may be acquired. It may occur temporarily after a bout of gastroenteritis. Certain digestive diseases and injuries to the small intestine can reduce the amount of enzymes produced. But for most people, lactase deficiency is a condition that develops naturally over time.
Absence of lactase will make lactose ferment in the intestine and cause symptoms.
Common symptoms include nausea, cramps, bloating, gas, and diarrhea. The severity of symptoms varies depending on the amount of lactose each individual can tolerate.
Most individuals will be diagnosed by the typical symptoms they experience. You may be asked to keep a diary for few days of what you eat and the symptoms you get. You may be advised to completely quit dairy products and see if the symptoms disappear. Then you will be asked to go back on the dairy products. If the symptoms reappear then the diagnosis is confirmed
The most common tests used to measure the absorption of lactose in the digestive system are the lactose tolerance test, the hydrogen breath test, and the stool acidity test.
Lactose intolerance is usually permanent in adults. The symptoms can be completely relieved by eliminating lactose from the diet by avoiding milk and milk products. Others can use lactase liquid or tablets to help digest the lactose. Other option would be to drink lactose-reduced milk available at supermarkets. This milk contains all the nutrients found in regular milk.
Milk is an important source of calcium in our diet. We need calcium for growth and repair of bones. If milk and milk products are avoided then consult your dietitian or physician to suggest other sources of calcium for your body.
Although lactose intolerance is widespread, it does not pose serious threat to our health.
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