| Subject | Contents |
| Definition | Lactose intolerance is the inability to digest lactose, a type of sugar found in milk and other dairy products. |
| Alternative Names | Lactase deficiency; Milk intolerance; Disaccharidase deficiency; Dairy product intolerance |
| Causes, incidence, and risk factors | Lactose intolerance occurs when the small intestine does not produce enough of the enzyme lactase. When people with lactose intolerance consume milk products, they may have symptoms such as abdominal bloating , excessive intestinal gas, nausea , diarrhea , and abdominal cramping . Lactose intolerance is very common in adults and is not dangerous. Many adults, by the time they are 20 years old (approximately 30 million Americans), have some degree of lactose intolerance. Lactose intolerance is common in premature babies, but in term birth babies, it generally does not show up until they are at least 3 years old. Eliminating milk from the diet can result in a deficiency of calcium, Vitamin D , riboflavin , and protein . Therefore, a milk substitute is a necessity. For infants under 2 years old, soy formulas are adequate substitutes. Good alternatives for toddlers and teens are soymilk or rice milk. Older children may also use lactase treated milk or find alternate dairy sources, such as cheese or yogurt. Lactose intolerance is more common in Asian, African, African-American, Native American, and Mediterranean populations than in northern and western Europeans. Lactase deficiency may also occur as a result of intestinal diseases such as celiac sprue and enteritis '>gastroenteritis , or it may follow gastroduodenal surgery. Temporary lactase deficiency can result from viral and bacterial enteritis , especially in children, when the mucosal cells of the intestine are injured. |
| Symptoms | abdominal crampsbloatingflatulenceweight lossmalnutrition(growth, slow (child 0-5 years)abdominal distentionabdominal fullness, gaseousdiarrheastools - floatingstools - foul smelling Symptoms often follow ingestion of milk products and are often relieved by withdrawal of milk products. |
| Signs and tests | lactose tolerance test lactose-hydrogen breath test small bowel biopsy that shows a negative mucosal lactase assay |
| Treatment | Removing milk products from the diet usually improves the symptoms. Lactase enzymes can be added to the milk (acidophilus milk) or taken in capsule or chewable tablet form. Fermented milk products such as yogurt can usually be tolerated. Other sources of calcium should be added to the diet if milk products are eliminated. Goat's milk can sometimes be tolerated. Drink it with meals, not alone. Buttermilk and cheeses have less lactose than milk. |
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| Expectations (prognosis) | Symptoms usually resolve when milk products are eliminated from the diet. |
| Complications | Weight loss and malnutrition are complications. |
| Calling your health care provider | If you or your child has symptoms of lactose intolerance, consult with your physician regarding dietary substitutions. Also call if symptoms worsen or do not improve with treatment, or if new symptoms develop. |
| Prevention | There is no known way to prevent the development of lactose intolerance. However, avoiding or restricting the amount of milk products eaten can reduce or eliminate the symptoms. |
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