Q&A: Lactose intolerance

by Patrika Tsai Patient Expert

Question: I have been told that I may have lactose intolerance. Does that mean I have to give up milk?

Answer: Lactose intolerance means that the body does not produce enough enzymes to digest lactose which is a sugar found in dairy products. People who are lactose intolerant produce little or no lactase. Lactase is an enzyme that breaks lactose down into smaller sugars that are absorbed by the body in the small intestine. Any lactose that is not digested and absorbed by the body passes on to the large intestine or colon. The large intestine contains bacteria which metabolize lactose and produce gas in the process. The gas leads to the bloated feeling that many lactose intolerant people feel after consuming large quantities of lactose. The sugar also pulls water and electrolytes into the stool which causes diarrhea and cramping.

Those affected by the condition

Lactose intolerance affects about 70% of the world's population. People of African, Asian, or Hispanic descent are more commonly affected. Most people produce lactase until at least 2 years of age. Depending on one's heritage, the body may then produce less lactose at different ages. For example, people of Asian descent may develop lactose intolerance at younger ages than people of African descent. Rarely, some people are born with lactase deficiency.

In some cases, lactose intolerance may be temporary. Because lactase is produced by cells in the small intestine, anything that injures the small intestine can result in lactose intolerance. A "stomach bug" like a virus or bacteria may cause infection and inflammation of the intestine resulting in diarrhea. Other causes of intestinal injury include gastrointestinal disorders like inflammatory bowel disease or celiac disease. Once the small intestine has a chance to heal, the lactose intolerance usually resolves.

Do I have it?

Lactose intolerance can be formally diagnosed with a breath test. However, a history of gas, bloating, and/or diarrhea associated with the consumption of lactose products is often sufficient to determine the problem. Healthcare providers often recommend a trial of a lactose free diet to see if the gastrointestinal symptoms resolve.

People who are lactose intolerant can often still tolerate a limited amount of lactose-containing products. They may be able to have a glass of regular milk with no ill effects. However, dairy products like yogurt and hard cheeses have lower levels of lactose compared to items like soft cheeses. Keep in mind that mozzarella cheese is a soft cheese and parmesan is a hard cheese. The higher lactose content of mozzarella than parmesan explains why a person may not be able to eat pizza but might be able to enjoy pasta with some parmesan with minimal problems.

Several dairy products are now available in the grocery store that have reduced amounts of lactose or are lactose-free for people with lactose intolerance who enjoy milk and other dairy products. The lactase enzyme is also sold over the counter as pills that can be taken with meals or snacks that contain lactose. Other alternatives include soy or rice milk. If you are diagnosed with lactose intolerance, take heart in the fact that you have some options.

Patrika Tsai
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Patrika Tsai

Patrika wrote for HealthCentral as a patient expert for Fitness & Exercise and Food & Nutrition.