Digestive Diseases: 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 in the body of lactase, an enzyme produced by the small intestine, which is needed to digest lactose. While lactose intolerance is not dangerous, its symptoms can be distressing.

What Are the Symptoms of Lactose Intolerance?

Symptoms include:

• Nausea
• Cramps
• Painful gas
• Bloating
• Diarrhea

Symptoms tend to develop 30 minutes to two 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 Foods Contain Lactose?

The most common foods that are high in lactose include milk, dairy products, ice cream and cheese. Lactose is also added to some foods, such as bread and baked goods, cereals, salad dressings, candies, and snacks.

Foods that contain whey, curds, milk by-products, dry milk solids and nonfat dry milk also contain lactose.

Lactose is also present in about 20% of prescription medications, such as birth control pills (oral contraceptives), and about 6% of over-the-counter medications, such as some tablets for stomach acid and gas.

Who Gets Lactose Intolerance?

Lactose intolerance is extremely common. 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% of African Americans, Jews, Mexicans and Native Americans, and 90% of Asians.

What Causes Lactose Intolerance?

For most people, lactose intolerance develops naturally as they grow older. The small intestine begins to produce less lactase in everyone after age two. Certain digestive diseases such as Crohn's disease, celiac disease (a digestive disease that damages the small intestine and interferes with absorption of nutrients from food) and injuries to the small intestine can also reduce the amount of lactase available to process lactose properly.

How Is Lactose Intolerance Diagnosed?

Usually lactose intolerance is diagnosed based solely on symptoms and relief of those symptoms when avoiding dairy products.

However, health care providers can perform a test called the hydrogen breath test to confirm the diagnosis. 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, a lactose intolerance test or a stool 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.

During the lactose intolerance test your blood sugar is measured over a two-hour period after drinking a lactose-loaded beverage. You are required to fast before the test. By measuring the level of sugar in the blood, the test indicates how well the body is digesting lactose.

The stool acidity test measures the amount of acid in the stool.

The lactose intolerance and hydrogen breath tests are not given to infants and very young children since they may cause severe diarrhea. If an infant or young child is having symptoms of lactose intolerance, the pediatrician will recommend changing from a cow's milk formula to a soy milk formula until the symptoms disappear and slowly reintroducing milk and dairy products at a later time. If needed to confirm the diagnosis, a stool acidity test may be given to infants and young children.

How Is Lactose Intolerance Treated?

Lactose intolerance is easily treated. People with the condition can usually find a level of lactose-containing foods that will not produce symptoms. Through trial and error, you can determine 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. Also, you may be better able to tolerate certain dairy products that contain less sugar, including cheese, yogurt and cottage cheese. The active cultures in yogurt produce some lactase enzymes to help digestion.

For people who get symptoms from very small amounts of lactose, commercially available lactase enzyme replacement (Lactaid) can be used. Lactaid converts lactose into its more digestible simple sugar components: glucose and galactose. The lactase enzyme is available in a liquid form to add to milk or in tablet form to take with solid food. Lactose-reduced milk, cheese, and other dairy products are also available at many supermarkets.

How Can I Get Enough Calcium if I'm Lactose Intolerant?

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 nondairy foods are good sources of calcium and don't contain lactose:

Vegetables

• Broccoli

• Chinese cabbage (bok choy)

• Dried peas and beans

• Greens (kale, collard, mustard, and turnip)

• Spinach

Seafood

• Mackerel

• Oysters, raw

• Sardines

• Shrimp

Other foods

• Calcium-enriched fruit juice

• Molasses

• Roasted almonds

• Tofu (calcium-enriched)

Eating 2-4 servings of these calcium-rich foods a day will help ensure that you are getting enough calcium in your daily diet.

Vitamin D will help your body use calcium. You can get adequate amounts of vitamin D from exposure to the sun, and by consuming fortified milk, eggs, and fish.

If you have trouble consuming enough calcium-rich foods in your daily diet, talk to your doctor or a dietitian about using a calcium supplement. The amount of calcium supplement you will need depends on how much calcium you are consuming through food sources.

Source: WebMD Medical Refrence in collaboration with The Cleveland Clinic