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Definition
Lactose intolerance is the inability to digest significant quantities of lactose. Lactose is a sugar found in milk and other dairy products.
Causes
Lactose intolerance is caused by an inadequate amount of the digestive enzyme lactase. Lactase breaks down the sugar lactose into sugars the bloodstream can more easily absorb. When not fully broken down, lactose ferments in the colon (large intestine) and causes symptoms.
Some people are born with the inability to make the enzyme lactase. Others develop the intolerance over time.
Causes of lactose intolerance include:
- Aging (lactase decreases as people age.)
- Gastroenteritis (or infection in the intestinal tract)
- Nontropical and tropical sprue
- Cystic fibrosis
- Immunoglobulin deficiencies
- Ulcerative colitis
Ulcerative Colitis
2008 Nucleus Medical Art, Inc.
Risk Factors
A risk factor is something that increases your chance of getting a disease or condition.
Risk factors include:
- Race: Black, Asian, or Native American
- Ethnicity: Mediterranean or Jewish
Symptoms
Symptoms of lactose intolerance generally begin within two hours of consuming milk or other dairy products. The severity of symptoms depends on how much lactase your body produces and how much lactose you eat.
Symptoms include: NauseaCrampingBloatingAbdominal rumbling soundsGasDiarrheaLoose stools DiagnosisThe doctor will ask about your symptoms and medical history and perform a physical exam. Often he or she will recommend a two-week trial period of eating no milk or milk products. If symptoms subside, you will be asked to consume milk products again. If milk causes symptoms to recur, you will be diagnosed with lactose intolerance.Your doctor may also order some tests, including:Lactose tolerance testmeasures the amount of glucose (simple sugar that is created from lactose) absorbed two hours after drinking a high-lactose liquid, indicating how well the body is digesting lactoseHydrogen breath testmeasures how much hydrogen is exhaled after drinking a high-lactose liquidStool acidity testmeasures lactic acid in the stool for infants and small childrenBiopsy of the small intestineonly performed in rare cases, this involves removing and testing a sample of tissue to confirm lactase deficiency TreatmentThough gene therapy has been suggested as a future treatment, there is currently no way to increase the bodys production of lactase. Treatment today focuses on managing symptoms. Experts counsel against complete elimination of dietary lactose, especially in children and adolescents, because milk and milk products provide sources of calcium and other food elements that are otherwise hard to replace. If complete elimination is chosen, then careful replacement of calcium is essential for good health.
Treatments include: Dietary Changes Dietary changes include: Keep a food diary of what you eat and what the reaction is. Discuss the findings with your doctor or a dietitian.Make gradual changes to your diet and record the results. Try eating a smaller portion before giving up on a dairy product. Many people can tolerate 4-8 ounces of milk at a time and may have better tolerance for some of the following dairy products made from milk: Ice creamSherbetCreamButterCheeseYogurtAged cheese and yogurt may be easier to tolerate than other dairy products.Try milk that is modified so it contains less lactose.Ask a dietitian for help choosing substitutes for dairy products or recommending supplements to ensure that you eat enough calcium. Nondairy foods rich in calcium include: SalmonSardinesOystersCollard greensBroccoli Read product labels because other foods containing lactose include: BreadsBaked goodsProcessed cerealsInstant potatoes and soupsMargarineNonkosher lunchmeatsSalad dressingsCandiesPancake mixesFrozen dinners Other words that indicate lactose are: WheyCurdsDry milk solidsNonfat dry milkMilk by-productsBe aware that some medications may contain small amounts of lactose. MedicationsYour doctor may recommend lactase enzymes if you can tolerate only small quantities of lactose. The enzyme supplements come in liquid and chewable form. A few drops of the liquid added to milk, which is allowed to sit overnight, can decrease the amount of lactose in the milk by 70% to 90%. Tablets are chewed or swallowed prior to eating foods that contain lactose.
PreventionThere are no guidelines for preventing lactose intolerance. RESOURCES: The American College of Gastroenterologyhttp://www.acg.gi.org American Gastroenterological Associationhttp://www.gastro.org CANADIAN RESOURCES: The Canadian Association of Gastroenterology (CAG)http://www.cag-acg.org/home.htm Dietitians of Canadahttp://www.dietitians.ca/ References: The American College of Gastroenterology website. Available at: http://www.acg.gi.org . American Gastroenterological Association website. Available at: http://www.gastro.org . Griffith's 5-Minute Clinical Consult. 1999 ed. Lippincott Williams & Wilkins; 1999. Heyman MB. Lactose intolerance in infants, children, and adolescents. Pediatrics. 2006;118:1279-1286. Montalta M, Curigliano V, Santoro L, et al. Management and treatment of lactose malabsorption. World J Gastroenterol. 2006;12:187-191. National Institute of Diabetes and Digestive and Kidney Diseases website. Available at: http://diabetes.niddk.nih.gov . Last reviewed November 2007 by Daus Mahnke, MDPlease be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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