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Lactose, the natural sugar found in milk products, is digested in the small bowel by means of the enzyme lactase. About 10% of adults in the United States are lactose intolerant. They do not have enough lactase to digest milk. When they eat milk or milk products, they develop crampy abdominal pain, bloating and diarrhea. Lactose intolerance can be acquired after gastric bypass or other gastric surgeries by as many as 10% of patients. When a person with a normal stomach drinks milk, it accumulates in the stomach and then is released slowly into the small intestine. There is enough lactase available to handle a small amount of milk at a time. After gastric bypass, milk passes directly through the gastric pouch into the small bowel at a much higher rate. The milk overwhelms the available enzyme and the lactose intolerance symptoms occur.

The strategies to deal with lactose intolerance that develops after surgery are to take milk products more slowly, eat thicker products such as yogurt or cheese rather than liquids milk, avoid milk products all together, or take an enzyme substitute Lactaid with meals.

The following information on the lactose-controlled diet and use of lactaid was provided by Marylyn Swift, RD from a hospital dietary manual. The use of lactaid is described in the text.

Lactose-Controlled Diet

Purpose The lactose-controlled diet is designed to prevent or reduce gastrointestinal symptoms of bloating, flatulence, cramping, nausea, and diarrhea associated with consumption of the disaccharide lactose.

Use The lactose-controlled diet is indicated for individuals with lactose intolerance or lactase deficiency (also called lactase nonpersistence). Individuals with primary lactase deficiency tolerate various levels of lactose while those having rare congenital lactase deficiency require strict avoidance of lactose-containing foods. Secondary lactose intolerance or lactase deficiency is usually transient and develops secondary to illness or disease and often requires limitation or avoidance of lactose.


The diet is a general one that restricts or eliminates lactose-containing foods. Lactose is primarily found in dairy products but may be present as an ingredient or component of various food products. (See Table 1 for lactose content of common foods and beverages.) Depending on individual tolerance, limiting products with lactose may help to alleviate symptoms.

Labels should be read carefully to identify sources of lactose. Dairy products that include milk, milk solids, whey, lactose, curds, skim milk powder, skim milk solids, sweet or sour cream, buttermilk, or malted milk are sources of lactose. Other possible sources of lactose are breads, candy, cookies, cold cuts, hot dogs, bologna, commercial sauces and gravies, dessert mixes, cream soups, some ready-to-eat cereals, frostings, chocolate drink mixes, salad dressings, sugar substitutes, and medications.

Dairy products can be consumed depending on individual tolerance. Most persons with lactase nonpersistence can consume milk without the development of symptoms, particularly if small portions of milk (4 fl oz to 6 fl oz) or lactose-containing foods are eaten at separate times during the day. The ingestion of solid food with lactose-containing beverages modifies lactose malabsorption.2 Food solids delay gastric emptying and/or provide endogenous lactase additional time to digest lactose.2.3 Cocoa and chocolate milk have a suppressive effect on human lactose intolerance as evidenced by significantly lowered mean breath hydrogen, bloating, and cramping.



Lactose (g)

Milk (1 cup)




1% and 2% low-fat






Sweetened, condensed






Yogurt, low-fat (1 cup)


Cottage cheese (1 cup)


Pasteurized processed cheese food (1 oz)


Other cheeses (1 oz)


Icecream (lcup)


Icemilk (1 cup)


Sherbet, orange (1 cup)


Half and half, light cream, whipped cream topping (1 tbsp)


Sourcream (ltbsp)


Lactose-reduced dairy products are available and are suitable substitutions for conventional lactose-containing products. Commercial products are available with varying degrees of lactose reduction. A 50% level of lactose reduction may be adequate to relieve signs and symptoms of milk intolerance in the majority of healthy adults with lactose malabsorption.5 Individuals may choose to use onventional dairy products and reduce the lactose levels themselves with commercially available, lactase enzyme drops or tablets. It has been suggested that yogurt is as effective as hydrolyzed lactose milk in alleviating symptoms of lactose intolerance.6 Lactase activity in yogurt may vary across brands.7 Yogurt that has endogenous cultures added post-pasteurization has more lactase activity.

Adding complex carbohydrates or soluble fiber may alleviate symptoms that originate in the small bowel.' The ingestion of milk with food and fiber components in the diet has been shown to improve symptoms of lactose intolerance.2 Dietary treatment for lactose intolerance in children incorporates some of the same recommendations as those made for adults. Specialized lactose-reduced products, as well as cultured and fermented dairy products, may be used in varying degrees for lactose-intolerant children. Ingestion of lactose- containing foods with solid food and fiber-containing food is recommended.

Infants with primary lactose intolerance should be managed with lactose-free, soy-based formulas or hydrolysate formulas if they are allergic to intact protein.8 Management of secondary lactose ntolerance is variable; well-nourished infants with nondehydrating gastroenteritis may be managed safely with diluted or even full-strength cow's milk formula after initial rehydration with a glucose-electrolyte solution.8

Related Physiology Primary lactase deficiency, a condition where the lactase enzyme activity level falls post weaning, is a common development with aging. It is most commonly seen in African Americans, Hispanics, Native Americans, Asians, and people of Jewish descent. Adult lactase deficiency is the most common of all enzyme deficiencies; well over half the world's adults are lactose intolerant .9 Secondary lactase deficiency can be attributed to mucosal injury from a condition or disease process such as regional enteritis, ulcerative colitis, Crohn's disease, gluten-induced enteropathy, and parasitic infections, or following antibiotic therapy and surgical procedures including gastrectomy, extensive bowel resection, and gastric bypass.



All beverages with allowed ingredients, soybean milks, other lactose-free supplements, lactose-hydrolyzed milk

Milk, milk products, or acidophilus milk as tolerance dictates

Breads and cereals

Whole-grain or enriched breads and cereals

Depending on tolerance, some breads and cereals prepared with milk or milk products may need to be avoided


Cakes, cookies, pies; flavored gelatin desserts; water ices made with allowed foods

Any prepared with milk or milk products (eg, sherbet, ice cream, ice milk, custard, pudding, commercial desserts, and mixes)


Butter or margarine; salad dressings; nondairy creamer; all oils

Any prepared with lactose-containing ingredients


All fruits and juices


Meats and meat substitutes

All meats, poultry; fish; eggs; peanut butter; dried peas and beans; hard, aged, and processed cheese, if tolerated yogurt as tolerated

Cold cuts and frankfurters that contain lactose filler; cottage cheese

Potatoes and potato substitutes

Potatoes; enriched rice; barley; noodles, spaghetti, macaroni, and other pastas

Potatoes or substitutes prepared with milk or milk products; mixes prepared with lactose-containing ingredients


Broth, bouillon; soups made with allowed ingredients

Soups made wit milk or milk products


Sugar; corn syrup; pure maple syrup; honey; jellies, jams; pure sugar candies; marshmallows

Chocolate; caramels; any candies made with lactose containing ingredients



Vegetables prepared with milk or milk products


All spices, seasonings, flavoring

Any prepared with milk or milk products

Lactose tolerance is variable; if an individual is asymptomatic, no restrictions are indicated, If an individual experiences adverse reactions to lactose, following a lactose-controlled diet is advisable. Symptoms associated with lactose intolerance usually subside within 3 to 5 days on a lactose- controlled diet.

Individuals can often identify discomfort associated with digesting lactose; however, true lactase deficiency can be diagnosed clinically with a breath hydrogen test. The breath hydrogen test measures hydrogen produced by colonic bacteria in the presence of unabsorbed sugars.

Adequacy Depending on individual choices, the diet can provide adequate amounts of all essential nutrients.. When dairy products are limited intake of calcium phosphorus, vitamins A and D, and riboflavin may be deficient. Use of dairy products within individual tolerance level and/or use of lactose hydrolyzed milk and milk products could satisfy these nutrient needs. Calcium supplementation is indicated if the diet does not provide adequate calcium.

Lactaid can be purchased in tablets, drops, or as lactase-treated milk and cheese products. Lactaid products are distributed by:

McNeil CPC
7050 Camp Hill Road
Fort Washington , PA 19034
Lactaid Hotline: 800ILACTAID, 9 am -5 pm Eastern time,
Monday through Friday

Dairy Ease products including tablets, drops, and lactase-treated milk are produced by:

Sterling Health
Division of Sterling Winthrop
90 Park Avenue


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