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Am Fam Physician. 2002;65(9):1855-1866

What is lactose intolerance?

If you have lactose intolerance, you have trouble digesting milk, ice cream and cheese. This condition is most common among people of Asian, American Indian, Hispanic and South American, and black heritage.

What causes lactose intolerance?

If you have lactose intolerance, you have trouble digesting milk because your body does not make enough lactase. Lactase is an enzyme that breaks down the natural sugar in milk. This sugar is called lactose.

What problems does lactose intolerance cause?

Here are the main problems caused by lactose intolerance in adults:

  • Rumbling tummy sounds

  • Stomach cramps

  • Stomach bloating

  • Diarrhea

The condition is a little different in each person. Some people with this problem can safely drink small amounts of milk, especially if they eat other foods with it. Other people can't drink any milk at all without having problems. The problems often start around age 2, when the body naturally starts making less lactase.

How is lactose intolerance treated?

You can make changes in your diet that will help you digest milk and milk products or you can get your calcium from other foods.

Milk and milk products are an important source of calcium. Your goal should be to get 1,200 to 1,500 milligrams of calcium each day, so you have strong bones. Children, teenagers, women who are pregnant or breastfeeding, and women who have gone through menopause should take calcium supplements if they can't drink enough milk or eat enough milk products to get this much calcium.

Ask your family doctor about calcium supplements. There are many kinds. The supplements with an oyster shell base are absorbed best. Check the amount of calcium on the product label. Some antacids, like Tums, have a lot of calcium in them. They make a good calcium supplement if you have to take antacids anyway.

Take smaller servings of milk products but have them more often. The smaller the serving, the less likely it is that you'll have problems.

Eat other foods when you drink milk. This slows the digestive process, and you have less chance of having the problems of lactose intolerance.

You may not have any trouble eating yogurt if it includes an “active culture.” The active culture in yogurt has an enzyme that breaks down lactose. Check the container label to see if active culture is included.

Ice cream, milkshakes and aged (hard) cheeses are easier than milk for most people with lactose intolerance, but they are high in fat. If your weight, cholesterol and triglyceride levels are normal, you can try them.

Look for lactose-reduced milk in your grocery store. It has about 70 percent less lactose than regular milk, but it costs a little more.

Try adding the lactase enzyme to regular milk. You can buy lactase at drug stores. Some people like the flavor of milk with added lactase because it tastes a little sweet.

Instead of drinking milk, eat foods that are high in calcium, like leafy greens (such as collard, kale and mustard greens), oysters, sardines, canned salmon (if you eat the salmon bones), shrimp, broccoli, and brussels sprouts. You can also buy orange juice with added calcium.

Where can I get more information about lactose intolerance?

National Digestive Diseases Information Clearinghouse

  • 2 Information Way

  • Bethesda, MD 20892-3570

  • Telephone: 1-800-891-5389

  • E-mail:

  • Web

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