What is lactose intolerance?

Lactose intolerance is your body’s dislike of the sugar in milk. This includes all dairy products. It is not the same as a milk allergy. It’s not a life-threatening problem. However, it is very common and causes stomach discomfort.

Lactose is a natural sugar that is found in dairy milk and dairy products such as cheese and yogurt. Lactose is digested by lactase, a protein (enzyme) in your small intestine.

Some people do not produce enough lactase to digest lactose. This is called lactose intolerance. Lactose intolerance is different from milk allergy, which is a more serious reaction to the protein in milk.

Symptoms of lactose intolerance

Lactose intolerance can cause discomfort within 30 minutes to 2 hours after you eat or drink something that contains lactose. Symptoms may include:

• Nausea.
• Diarrhea.
• Cramps or pain in the abdomen.
• A full, tight, or painful feeling in the abdomen (bloating).
• Gas.

Sometimes you may hear gurgling noises in your stomach.

What causes lactose intolerance?

Causes of lactose intolerance may include:

• Normal aging. The ability to produce lactase may lessen with age, causing lactose intolerance over time.
• Being born without the ability to make lactase.
• Digestive diseases such as gastroenteritis or inflammatory bowel disease (IBD).
• Surgery or injury to your small intestine.
• Infection in your intestines.
• Certain antibiotic medicines and cancer treatments.

People who are lactose intolerant don’t have lactase. Lactase is an important enzyme inside your small intestine. It helps your body digest the sugar in dairy foods. Some people don’t have lactase because of their family medical history. That is rare. Some people don’t have lactase because they have an infection or a certain disease. Celiac disease, Crohn’s disease, and inflammatory bowel disease (IBD) are the most common diseases that can cause it.

How is lactose intolerance diagnosed?

The “milk challenge” is the easiest way to see if you are lactose intolerant. Avoid eating and drinking all dairy products such as milk, ice cream, and cheese for several days. Drink a glass of milk and see if you have all the usual stomach problems within an hour of drinking it. If you do, you are probably lactose intolerant.

If you aren’t sure, see your doctor. Your doctor will ask you questions about your symptoms and your history with dairy products. If he or she is unsure, there are several other kinds of tests, including:

• Lactose tolerance test. A blood test to test for lactose intolerance or a lactose intolerance gene. You will be asked to drink a beverage with lactose in it. Two hours later, a medical technician or nurse will insert a small needle connected to a syringe into the vein in your arm to collect a sample of your blood to send to a lab.
• A hydrogen breath test or Lactose breath test . This can be done in a hospital, lab, or your doctor’s office. When you arrive, you will be asked to drink a beverage that contains lactose. After 15 minutes, you’ll be asked to blow into balloon-like bags every 15 minutes. The air inside the bags will be tested for hydrogen. If your air contains a lot of hydrogen, you are probably lactose intolerant. The full test takes about 2 hours.
• Stool acidity test (where you provide a lab with a stool sample). This is a common test for infants and young children.
• Genetics test. This involves taking a sample of your genes through a blood or a saliva (spit) sample.

A surgical biopsy of your intestine. This is done at a hospital. It requires anesthesia (medicine that puts you into a deep sleep). Your doctor will make a small cut in your stomach near your small intestine. He or she will insert a small cutting tool and scope to see your intestine. The doctor will take a sample. The sample will be sent to a lab.

Can lactose intolerance be prevented or avoided?

You can reduce the discomfort of lactose when you:

• Cut back on the amount of dairy you eat or drink. For example, one serving of milk should be ¼ or ½ cup.
• Drink it with other food (not more dairy).
• Wait several hours before having more.
• Choose foods with less lactose. Those include buttermilk and hard cheeses (cheddar, parmesan, Romano).
• Substitute soy or nondairy products, such as nondairy coffee creamers.
• Use supplements that help you digest lactose. There are pills you can chew before you eat or drink milk products.
• Look for lactose-free foods in grocery stores.

If yogurt doesn’t bother you, eat that. Yogurt helps with stomach upset. Talk to your doctor about vitamin supplements. Eat foods that are naturally high in calcium. These include leafy greens, oysters, sardines, canned salmon, shrimp, and broccoli. Choose orange juice and cereals with added calcium.

Lactose intolerance treatment

There is no cure for lactose intolerance. Watching what you eat can help reduce stomach pain, gas, and diarrhea.

• Cut back on the amount of dairy you eat or drink. For example, one serving of milk should be ¼ or ½ cup.
• Drink it with other food (not more dairy).
• Wait several hours before having more.
• Choose foods with less lactose. Those include buttermilk and hard cheeses (cheddar, parmesan, Romano).
• Substitute soy or nondairy products, such as nondairy coffee creamers.
• Use supplements that help you digest lactose. There are pills you can chew before you eat or drink milk products.
• Look for lactose-free foods in grocery stores.

If yogurt doesn’t bother you, eat that. Yogurt helps with stomach upset. Talk to your doctor about vitamin supplements. Eat foods that are naturally high in calcium. These include leafy greens, oysters, sardines, canned salmon, shrimp, and broccoli. Choose orange juice and cereals with added calcium.

Lactose tolerance varies from person to person. Some people may be able to eat or drink small amounts of products that contain lactose, and other people may need to avoid all foods and drinks that contain lactose. Talk with your health care provider about what treatment is best for you.

Living with lactose intolerance

Living without stomach pain, gas, and bloating is up to you. If you watch what you eat and limit the amount of dairy, you will be more comfortable.

Questions to ask your doctor

• Is there a “lactose pill” I can take just before eating dairy?
• Is ice cream as bad as milk? How about frozen yogurt?
• Could there be other reasons for my stomach pain, gas, bloating, and diarrhea?
• What are the symptoms of a dairy allergy?

Follow these instructions at home:

• Limit or avoid foods, beverages, and medicines that contain lactose, as told by your health care provider. Keep track of which foods, beverages, or medicines cause symptoms so you can decide what to avoid in the future.
• Read food and medicine labels carefully. Avoid products that contain:
  • Lactose.
  • Milk solids.
  • Casein.
  • Whey.
• Take over-the-counter and prescription medicines (including lactase tablets) only as told by your health care provider.
• If you stop eating and drinking dairy products (eliminate dairy from your diet), make sure to get enough protein, calcium, and vitamin D from other foods. Work with your health care provider or a diet and nutrition specialist (dietitian) to make sure you get enough of those nutrients.
• Choose a milk substitute that is fortified with calcium and vitamin D.
  • Soy milk contains high-quality protein.
  • Milks that are made from nuts or grains (such as almond milk and rice milk) contain very small amounts of protein.
• Keep all follow-up visits as told by your health care provider. This is important.

Contact a health care provider if:

• You have no relief from your symptoms after you have eliminated milk products and other sources of lactose.

Get help right away if:

• You have blood in your stool.
• You have severe abdomen (abdominal) pain.

Summary

• Lactose is a natural sugar that is found in dairy milk and dairy products such as cheese and yogurt. Lactose is digested by lactase, which is a protein (enzyme) in the small intestine.
• Some people do not produce enough lactase to digest lactose. This is called lactose intolerance.
• Lactose intolerance can cause discomfort within 30 minutes to 2 hours after you eat or drink something that contains lactose.
• Limit or avoid foods, beverages, and medicines that contain lactose, as told by your health care provider.