Lactase deficiency; Milk intolerance; Disaccharidase deficiency; Dairy product intolerance
Lactose intolerance is the inability to digest lactose. Lactose is a type of sugar found in milk and other dairy products.
Lactose intolerance happens when the small intestine does not make enough of the enzyme lactase. Enzymes help the body absorb foods. Not having enough lactase is called lactase deficiency.
Babies' bodies make this enzyme so they can digest milk, including breast milk.
Premature babies sometimes have lactose intolerance. Children who were born at full term usually do not show signs of lactose intolerance until they are at least 3 years old.
Lactose intolerance can begin at different times in life. In Caucasians, it usually affects children older than age 5. In African Americans, lactose intolerance often occurs as early as age 2.
Lactose intolerance is more common in people with Asian, African, Native American, or Mediterranean ancestry than it is among northern and western Europeans.
Lactose intolerance is very common in adults and is not dangerous. Approximately 30 million American adults have some amount of lactose intolerance by age 20.
Causes of lactose intolerance include:
Symptoms often occur 30 minutes to 2 hours after you eat or drink milk products, and are often relieved by not eating or drinking milk products. Large doses of milk products may cause worse symptoms.
Infants or children may have slow growth or weight loss.
Decreasing or removing milk products from the diet usually improves the symptoms.
Most people with low lactase levels can drink 2 - 4 ounces of milk at one time (up to one-half cup) without having symptoms. Larger (more than 8 oz.) servings may cause problems for people with lactase deficiency.
These milk products may be easier to digest:
You can add lactase enzymes to regular milk or take these enzymes in capsule or chewable tablet form.
Not having milk in the diet can lead to a shortage of calcium, vitamin D, riboflavin, and protein.
You may need to find new ways to get calcium into your diet (you need 1,200 - 1,500 mg of calcium each day):
Read food labels. Lactose is also found in some non-milk products -- including some beers.
Symptoms usually go away when you remove milk products or other lactose containing products from the diet.
Weight loss and malnutrition are possible complications.
Call your health care provider if:
There is no known way to prevent lactose intolerance.
If you have the condition, avoiding or restricting the amount of milk products in your diet can reduce or prevent symptoms.
Genauer CH, Hammer HF. Maldigestion and malabsorption. In: Feldman M, Friedman LS, Sleisenger MH, eds. Sleisenger & Fordtran's Gastrointestinal and Liver Disease. 9th ed. Philadelphia, Pa: Saunders Elsevier; 2010: chap 101.
Lactose intolerance. The National Digestive Diseases Information Clearinghouse (NDDIC). NIH Publication No. 09-2751. June 2009.
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