What is lactose intolerance?
Lactose intolerance is the inability to digest lactose, the sugar primarily found in milk and dairy products. It is caused by a shortage of lactase in the body, an enzyme produced by the small intestine that is needed to digest lactose. While lactose intolerance is not dangerous, its symptoms can be distressing.
What are the symptoms of lactose intolerance?
Symptoms of lactose intolerance occur when there is not enough lactase being produced by the body to digest the lactose consumed. Symptoms of lactose intolerance include nausea, cramps, gas, bloating or diarrhea within 30 minutes to 2 hours after consuming milk or dairy products. The severity of symptoms varies, depending on the amount of lactose an individual person can tolerate. Some people may be sensitive to extremely small amounts of lactose-containing foods while others can eat larger amounts before they notice symptoms.
What causes lactose intolerance?
Some causes of lactose intolerance are known. Certain digestive diseases, such as Crohn's disease, celiac sprue (an inherited disorder affecting the lining of the small intestine) and injuries to the small intestine can reduce the amount of lactase available to process lactose properly. If the small intestine is injured, lactose intolerance may be temporary, with symptoms improving after the intestine has healed.
Who is affected by lactose intolerance?
For most people, lactose intolerance develops over time as the body produces less lactase.
It is estimated that 30 to 50 million Americans have some degree of lactose intolerance. Certain racial and ethnic populations are more affected than others, including 75 percent of African Americans, Jews, Mexicans and Native Americans; as well as 90 percent of Asians.
How is lactose intolerance diagnosed?
The most common test for the diagnosis of lactase deficiency is the hydrogen breath test. This test is done at an outpatient clinic or doctor's office. In practice, many doctors will ask patients who suspect they have lactose intolerance to avoid milk and dairy products for one or two weeks to see if their symptoms subside, and will then confirm the diagnosis with the hydrogen breath test.
The hydrogen breath test measures the amount of hydrogen in the breath after drinking a lactose-loaded beverage. Raised levels of hydrogen in the breath within 90 minutes indicate improper digestion of lactose. Certain foods, medications and cigarettes can affect the test result, so the patient will be instructed to avoid these prior to taking the test.
Foods high in lactose
The most common high-lactose foods include:
- Milk, milkshakes and other milk-based beverages
- Whipping cream and coffee creamer
- Ice cream, ice milk, sherbet
- Cheese
- Butter
- Puddings, custards
- Cream soups, cream sauces
- Foods made with milk
Other foods that MAY contain lactose in smaller quantities include:
- Bread and baked goods
- Milk chocolate
- Salad dressings and sauces
- Breakfast cereals and cereal bars
- Instant potatoes, soups, rice and noodle mixes
- Lunch meats
- Candies and other snacks
- Mixes for pancakes, biscuits and cookies
- Margarine
- Organ meats (such as liver)
- Sugar beats, peas, lima beans
How do I know if processed foods contain lactose?
When buying food, read the ingredients on food labels carefully. Ingredients derived from milk that contain lactose include:
- Whey
- Casein
- Caseinates
- Lactose
- Nougat
- Butter
- Cheese
- Curds
- Milk by-products
- Nonfat dry milk
- Dry milk solids
- Dry milk powder
Depending on the severity of your symptoms, you may need to avoid or limit foods containing these ingredients.
Lactose is also present in about 20 percent of prescription medications, such as birth control pills (oral contraceptives), and about 6 percent of over-the-counter medications, such as some tablets for stomach acid and gas. These medications usually affect only people with severe lactose intolerance. Ask your health care provider which medications contain lactose, and read the labels on over-the-counter medications to check their lactose content.
How is lactose intolerance treated?
Lactose intolerance is easily treated. The goal of treatment is to control symptoms through dietary changes.
People with lactose intolerance can usually find a level of lactose-containing foods that will not produce symptoms. You can learn through trial and error what amount and type of lactose-containing products you can tolerate.
In addition, you may try consuming small amounts of milk or dairy products with meals because lactose may be better tolerated when eaten with other foods. You may be better able to tolerate certain dairy products that contain lower amounts of lactose, including cheese, yogurt and cottage cheese.
For people who get symptoms from very small amounts of lactose, or for those who have difficulty limiting their intake of lactose-containing foods, lactase enzyme replacements (such as Dairy Ease or Lactaid) can be used. These products are available over-the-counter and come in liquid form to add to milk or in tablet form that can be taken when eating solid food containing lactose. Lactose-reduced milk, cheese and other lactose-reduced dairy products are also available at many supermarkets.
How can I maintain a balanced diet?
Milk and dairy products are a major source of calcium, an essential nutrient for the growth and repair of bones and teeth throughout life. Calcium is also essential for blood to clot normally, muscles and nerves to function properly, and the heart to beat normally.
People who are lactose intolerant don't necessarily have to consume milk and dairy products to get the calcium they need to maintain proper nutrition.
The following non-dairy foods are good sources of calcium that don't contain lactose:
Vegetables
- Broccoli
- Chinese cabbage (bok choy)
- Dried peas and beans
- Greens: kale, collard, mustard, turnip
- Spinach
Seafood
- Canned salmon with soft bones
- Mackerel
- Oysters, raw
- Sardines
- Shrimp
Other foods
- Calcium-enriched fruit juice
- Molasses
- Roasted almonds
- Tofu (calcium-enriched)
If you have trouble consuming enough calcium-rich foods in your daily diet, talk to your health care provider or a dietitian about taking a calcium supplement. The amount of calcium you will need from a supplement will depend on how much calcium you are consuming through food sources.
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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 1/30/2006...#7317
