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Lactose intolerance

dairy products including milk, eggs, cheese, and ice cream

Does your stomach churn after you drink milk? Do you have diarrhea soon afterward? If so, you may be lactose intolerant.

Lactose intolerance means that you cannot digest foods with lactose in them. Lactose is the sugar found in milk and foods made with milk. You cannot digest lactose because your small intestine does not have enough of an enzyme called lactase.

Symptoms of lactose intolerance usually begin within a half hour to two hours after eating or drinking foods that contain lactose. Symptoms include:

  • Diarrhea
  • Nausea
  • Stomach cramps
  • Bloating
  • Gas

Lactose intolerance is not the same as milk allergy. Milk allergy is due to a problem with your body's defense system, called the immune system. In contrast, lactose intolerance is caused by not having enough lactase. Symptoms of milk allergy start right after drinking milk. But symptoms of lactose intolerance take longer to develop.

Lactose intolerance is more common in some ethnic groups — in particular, Asians, blacks, Hispanics, and Native Americans. The condition is also more common in older people, since our bodies produce fewer lactase enzymes as we age.

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Dealing with lactose intolerance

Although it is uncomfortable, the condition is not serious. One way to avoid symptoms is to eat less food with lactose. Besides milk, lactose is also in:

  • Ice cream
  • Sherbet
  • Cream
  • Butter
  • Some cheeses (including cottage cheese)
  • Yogurt

Lactose is also added to some prepared foods, such as:

  • Breads and other baked goods
  • Cereals
  • Mixes for cakes, cookies, pancakes, and biscuits
  • Instant potatoes, soups, and breakfast drinks
  • Lunch meats
  • Frozen dinners
  • Salad dressings
  • Margarines

If you plan to eat foods with lactose, you can try taking a lactase tablet just before eating. The tablet supplies your body with the lactase that it's missing. Another option is to drink lactose-reduced milk. It contains the same nutrients as milk, including calcium and vitamin D, but less lactose.

Some people with lactose intolerance find that they can eat a small amount of some foods with lactose. For instance, they may be able to eat yogurt or aged cheeses, like cheddar or Swiss. Others find that they can tolerate milk if they drink it in small amounts or drink it at meals.

If you cannot tolerate any amount of milk or milk products, you should find other ways to get enough calcium. Calcium is needed for healthy bones and teeth. See our list of foods rich in calcium. Also, ask your doctor if you should take a calcium supplement every day.

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Content last updated: June 17, 2008.

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