University of Iowa Health Science Relations and
Joel Weinstock, MD
Professor of Internal Medicine
Peer Review Status: Internally Peer Reviewed

Cereal with milk, cottage cheese, creamy sauces, and ice cream--the milk products that are routine mealtime items for many people may cause gastrointestinal problems for others who have developed lactose intolerance. This condition results from a lack of an enzyme, lactase, in the intestines, says Dr. Joel Weinstock, professor of internal medicine at the University of Iowa College of Medicine.

The lactase enzyme is necessary for digesting the sugar lactose that is found in milk and dairy products, explains Weinstock, who also is Director of the Division of Gastroenterology-Hepatology and Center for Digestive Diseases and a staff physician at UI Hospitals. "Most everyone is born with an adequate supply of the enzyme, but as people grow older, some lose part of the enzyme," he says. Scientists do not know why some people lose the enzyme and why others don't.

The symptoms of the condition depend upon the severity of the intolerance. Most people who cannot tolerate lactose feel bloated and pass lots of gas when they consume too many milk products, and some may develop diarrhea, Weinstock says. The symptoms generally disappear when milk products are reduced or eliminated from the diet. Lactose intolerance is not serious and does not lead to other medical problems, he notes.

The tendency for this intolerance usually is inherited and certain racial groups, such as Asians, Arabs, Jews, and blacks are more likely to develop the condition, he says. Lactose intolerance is very common in older adults and rare in children.

To diagnose the condition, a physician may give a patient a lactose tolerance test or simply remove milk products from the diet to see the consequence. Once it has been determined that a patient is lactose intolerant, there are several ways to deal with the condition. Those with a moderate case may feel better by simply reducing the amount of milk products in their diets. In more severe cases, milk products may need to be cut out of the diet entirely, Weinstock says.

Fortunately there are milk substitutes on the market that can replace the real thing. Those with lactose intolerance who are still milk lovers can drink milk if they first treat it with an enzyme. Once mixed into the milk, the enzyme breaks down the lactose, making it safe for use, Weinstock explains. The enzyme is available at many pharmacies.

There are many foods other than the above-mentioned milk products that may contain lactose. They include coffee creamers, breads, and prepackaged foods, he says. Cheese and yogurt are usually better tolerated than other milk products. The cultures in yogurt contain the enzyme lactase, which aids the digestion of lactose. Also, skim milk contains a slightly higher concentration of lactose than whole milk and should be avoided, he adds.

If plagued by gastrointestinal problems or discomfort, see your physician to determine if you have lactose intolerance or other conditions that cause similar symptoms, Weinstock says.