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Lactose Intolerance


Topic Overview

Picture of the lower digestive system

What is lactose intolerance?

Lactose intolerance means the body cannot easily digest lactose, a type of natural sugar found in milk and dairy products. This is not the same thing as a food allergy to milk.

When lactose moves through the large intestineClick here to see an illustration. (colon) without being properly digested, it can cause uncomfortable symptoms such as gas, belly pain, and bloating. Some people who have lactose intolerance cannot digest any milk products. Others can eat or drink small amounts of milk products or certain types of milk products without problems.

Lactose intolerance is common in adults. It occurs more often in Native Americans and people of Asian, African, and South American descent than among people of European descent.

A big challenge for people who are lactose-intolerant is learning how to eat to avoid discomfort and to get enough calcium for healthy bones.

What causes lactose intolerance?

Lactose intolerance occurs when the small intestineClick here to see an illustration. does not make enough of an enzyme called lactase. Your body needs lactase to break down, or digest, lactose.

Lactose intolerance most commonly runs in families, and symptoms usually develop during the teen or adult years. Most people with this type of lactose intolerance can eat some milk or dairy products without problems.

Sometimes the small intestine stops making lactase after a short-term illness such as the stomach flu or as part of a lifelong disease such as cystic fibrosis. Or the small intestine sometimes stops making lactase after surgery to remove a part of the small intestine. In these cases, the problem can be either permanent or temporary.

In rare cases, newborns are lactose-intolerant. A person born with lactose intolerance cannot eat or drink anything with lactose.

Some premature babies have temporary lactose intolerance because they are not yet able to make lactase. After a baby begins to make lactase, the condition typically goes away.

What are the symptoms?

Symptoms of lactose intolerance can be mild to severe, depending on how much lactase your body makes. Symptoms usually begin 30 minutes to 2 hours after you eat or drink milk products. If you have lactose intolerance, your symptoms may include:

  • Bloating.
  • Pain or cramps.
  • Gurgling or rumbling sounds in your belly.
  • Gas.
  • Loose stools or diarrhea.
  • Throwing up.

Many people who have gas, belly pain, bloating, and diarrhea suspect they may be lactose-intolerant. The best way to check this is to avoid eating all milk and dairy products to see if your symptoms go away. If they do, then you can try adding small amounts of milk products to see if your symptoms come back.

If you feel sick after drinking a glass of milk one time, you probably do not have lactose intolerance. But if you feel sick every time you have milk, ice cream, or another dairy product, you may have lactose intolerance.

Sometimes people who have never had problems with milk or dairy products suddenly have lactose intolerance. This is more common as you get older.

If you think you might have lactose intolerance, talk with your doctor. He or she can make sure that your symptoms are caused by lactose intolerance and not by another problem.

How is lactose intolerance diagnosed?

A doctor can usually tell whether you have lactose intolerance by asking questions about your symptoms. He or she may also ask that you avoid dairy products for a short time to see if your symptoms improve.

Sometimes doctors order a hydrogen breath test or a blood sugar test to confirm the diagnosis. These simple tests check to see if you are digesting lactose normally.

How is it treated?

There is no cure for lactose intolerance. But you can treat your symptoms by limiting or avoiding milk products. Some people use milk with reduced lactose, or they substitute soy milk and soy cheese for milk and milk products. Some people who are lactose-intolerant can eat yogurt without problems, especially yogurt with live cultures. You can also take dietary supplements called lactase products that help digest lactose. In time, most people who have lactose intolerance get to know their bodies well enough to avoid symptoms.

One of the biggest concerns for people who are lactose-intolerant is making sure they get enough of the nutrients found in milk products, especially calcium. Calcium is most important for children, teens, pregnant women, and women after menopause. There are many nondairy foods that contain calcium, including:

  • Broccoli, okra, kale, collards, and turnip greens.
  • Canned sardines, tuna, and salmon.
  • Calcium-fortified juices and cereals.
  • Calcium-fortified soy products such as soy milk, tofu, and soybeans.
  • Almonds.

Frequently Asked Questions

Learning about lactose intolerance:

Being diagnosed:

Getting treatment:

Ongoing concerns:

eMedicineHealth Medical Reference from Healthwise

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