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Student Health Services

Lactose Intolerance

What is Lactose Intolerance?

People who have lactose intolerance cannot comfortably eat foods and beverages with lactose, such as milk. Lactose is the main sugar in milk. It is digested in the intestines by lactase, an enzyme that helps break lactose into smaller sugars. If a person does not produce lactase, the lactose goes undigested and is fermented by the normal bacteria found in the intestine.

Most infants produce lactase enzyme from birth, but the amount tends to decrease by adulthood. In the United States, the incidence of lactose intolerance varies for different populations. On average, 80% of Asian and Native Americans are lactose intolerant, 75% of African Americans, 51% of Hispanic Americans and 21% of Caucasian Americans.

Is Lactose Intolerance the Same as a Milk Allergy?

No. Lactose intolerance should not be confused with a milk allergy. A milk allergy is an allergic reaction to the protein components in milk, not the sugar in milk. Individuals with milk allergy usually must avoid all milk products. Those with lactose intolerance can use certain dairy products or other foods that are low in lactose.

What are the Symptoms of Lactose Intolerance?

Symptoms vary with individuals and should be discussed with your physician. Typical symptoms include nausea, cramping and bloating, pain, intestinal gas and diarrhea. Symptoms may appear any time from 15 minutes to several hours after eating lactose-containing foods and beverages.

Should All Lactose-Containing Foods be Eliminated from My Diet?

Remember that each individual's tolerance level to lactose is different. Nutritionally balanced meals can be planned based on your tolerance level. Talk with a registered dietitian (RD) for assistance in planning high-nutrient, low-lactose menus. Consider these practical tips for tolerating lactose in your diet.

  • Try commercial milk substitutes, low-lactose fluid milk products and soy milk/soy formulas found in grocery stores. Lactase enzyme tablets and drops that can be added to milk are also available.
  • Consume dairy products with your meals to dilute lactose. Eat smaller portions of lactose-containing foods.
  • Try cultured dairy products such as yogurt that contain active cultures - check the label. They are lower in lactose and may be tolerated better.
  • Select hard cheese, like cheddar, which are low in lactose and high in calcium.
  • Include calcium-rich dark green, leafy vegetables, such as broccoli and greens, in daily meals.
  • Consult your physician or registered dietitian about appropriate vitamin/mineral or calcium supplements.

Are There Nutritional Concerns Associated with Lactose-Restricted Diets?

Dairy products provide protein, calcium, riboflavin, vitamin A, vitamin D, phosphorus and magnesium. Of special concern is calcium because of its importance for healthy teeth and bones and as a factor in preventing osteoporosis, a condition of weakened bones. If you are very sensitive to even small amounts of lactose, include other calcium-rich foods such as calcium-fortified juices, broccoli, greens and canned sardines and salmon with bones, in daily meals and snacks. Remember, variety and moderation are the keys to a healthy diet.

Which Foods Contain Lactose?

Lactose is usually found in products containing milk or milk solids. If you are very sensitive to lactose, you may need to check labels more carefully. Key words to look for on food labels are whey, lactose, nonfat milk solids, margarine and sweet or sour cream. A variety of prepared, processed and baked foods contain small amounts of lactose. Examples are breads, dry cereals, cold cuts, cream soups, salad dressings, candy, cookies, drink mixes, sugar substitutes and some medications. However, most lactose-intolerant people do not have a problem with the small amount of lactose in these foods.