Lactose is a type of sugar found in milk and other dairy products. Lactose intolerance develops when the small intestine does not make enough of an enzyme called lactase. The body needs this enzyme to digest lactose.
Cutting down or removing milk products from your diet usually eases 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.
Milk products may be easier to digest include:
Buttermilk and cheeses (have less lactose than milk)
Fermented milk products, such as yogurt
Ice cream, milkshakes, and aged or hard cheeses
Lactose-free milk and milk products
Lactase-treated cow's milk for older children and adults
Soy formulas for infants younger than 2 years
Soy or rice milk for toddlers
You can add lactase enzymes to regular milk, or take these enzymes in capsule or chewable tablet form.
Not having milk in your diet can lead to a shortage of calcium, vitamin D, riboflavin, and protein. You need 1,000 - 1,500 mg of calcium each day depending on your age and gender. Some things you can do to get more calcium in your diet are:
Take calcium supplements
Eat foods that have more calcium (such as leafy greens, oysters, sardines, canned salmon, shrimp, and broccoli)
Drink orange juice that contains added calcium
Read food labels. Lactose is also found in some non-milk products -- including some beers.
Symptoms usually go away after removing milk products and other lactose containing products from your diet. Infants or children may have slow growth or weight loss without a change in diet.
Calling your health care provider
Call your health care provider if:
You have an infant younger than 2 or 3 years old who has symptoms of lactose intolerance.
Your child is growing slowly or not gaining weight.
You or your child has symptoms of lactose intolerance and you need information on food substitutes.
Your symptoms get worse or do not improve with treatment, or you develop new symptoms.
There is no known way to prevent lactose intolerance. You can prevent symptoms by avoiding foods with lactose. Read food labels carefully. Lactose is also found in some non-milk products, including some beers.
Hogenauer C, 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, updated April 12, 2012.
Semrad CE. Approach to the patient with diarrhea and malabsorption. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 142.
David C. Dugdale, III, MD. Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and George F. Longstreth, MD, Department of Gastroenterology, Kaiser Permanente Medical Care Program, San Diego, California. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.