Lactose Intolerance

Lifestyle Preventative Health and Medications > Lactose Intolerance

Patient Education: Lactose Intolerance

What is Lactose Intolerance?  

Lactose intolerance means the body cannot easily digest lactose, a type of natural sugar found in milk and dairy products. This is not the same thing as a food allergy to milk. Lactose intolerance is common in adults. It occurs more often in people of Asian, African, and South American descent than among people of European descent.

Lactose intolerance occurs when the small intestine does not make enough of an enzyme called lactase. Normally, lactase turns milk sugar into two simple sugars — glucose and galactose — which are absorbed into the bloodstream through the intestinal lining. If you’re lactase deficient, lactose in your food moves into the colon instead of being processed and absorbed. In the colon, normal bacteria interact with undigested lactose, causing the signs and symptoms of lactose intolerance.

What are the symptoms? 

The signs and symptoms of lactose intolerance usually begin 30 minutes to two hours after eating or drinking foods that contain lactose. Symptoms of lactose intolerance can be mild to severe, depending on how much lactase your body makes. Symptoms usually begin 30 minutes to 2 hours after you eat or drink milk products. If you have lactose intolerance, your symptoms may include:

  • Diarrhoea
  • Nausea, and sometimes, vomiting
  • Abdominal cramps
  • Bloating
  • Gas

How is lactose intolerance diagnosed? 

An easy way to see if lactose intolerance may be the cause of your symptoms is to avoid eating all milk and dairy products to see if your symptoms go away. Sometimes doctors order a hydrogen breath test to confirm the diagnosis. This test measures the amount of hydrogen in a person’s breath. Normally, only a small amount of hydrogen is detectable in the breath when a person eats or drinks and digests lactose.

However, undigested lactose produces high levels of hydrogen. For this test, the patient drinks a beverage that contains a known amount of lactose. A health care provider asks the patient to breathe into a balloon-type container that measures breath hydrogen level. In most cases, a health care provider performs this test at a hospital, on an outpatient basis. Smoking and some foods and medications may affect the accuracy of the results. A health care provider will tell the patient what foods or medications to avoid before the test.

How do you treat lactose intolerance? 

There is no cure for lactose intolerance, but limiting your intake of food and drink containing lactose usually helps to control the symptoms.

Depending on what dairy products you’re able to eat, you may also require additional calcium and vitamin D supplements to keep your bones strong and healthy.

In some cases, your GP may refer you to a dietitian for further advice.
In addition to dietary changes, lactase substitutes may also be helpful. These are drops or tablets you can take with your meals or drinks to improve your digestion of lactose.