Health Encyclopedia

Lactose Intolerance in Children

What is lactose intolerance?

Lactose intolerance is a condition caused when a person can't make enough of an enzyme called lactase. Without enough lactase, the body can't digest lactose, a sugar found in milk and milk products.

Lactase is normally made by cells lining the small intestine where it breaks lactose down into a form that can be absorbed by the blood. A lack of lactase can cause uncomfortable symptoms for some people. Those who do have symptoms are said to be lactose intolerant.

The disorder affects some groups of people more than others:

  • African-American, Jewish, Mexican-American, Native American, and Asian-American adults are commonly lactose intolerant.

Lactose intolerance is least common among people with a northern European heritage.

What causes lactose intolerance?

Digestive diseases or injuries to the small intestine can reduce the amount of enzymes made. This is what causes lactose intolerance most often in young children. However, most cases of lactose intolerance develop over a period of  years in teens and adults.

What are the symptoms of lactose intolerance?

The following are the most common symptoms for lactose intolerance. Symptoms begin to appear in Caucasian children after age 5, and in African-American children as early as 2 years of age. Common symptoms, which start about 30 minutes to 2 hours after eating foods or beverages containing lactose, may include:

  • Nausea

  • Cramps

  • Bloating

  • Abdominal pain

  • Gas

  • Diarrhea

The severity of symptoms varies depending on the amount of lactose consumed and the amount each person can handle.

The symptoms of lactose intolerance may look like other conditions or medical problems. Always consult your child's health care provider for a diagnosis.

How is lactose intolerance diagnosed?

The most common tests used to measure the absorption of lactose in the digestive system include:

  • Lactose tolerance test. This test measures the absorption of lactose in the digestive system. After fasting, the person drinks a liquid that contains lactose. The diarrheal stools are then tested for lactose for the next 24 hours.

  • Hydrogen breath test. The person drinks a lactose-heavy beverage. The breath is then analyzed at regular intervals to measure the amount of hydrogen. When high levels of hydrogen are in the breath, improper digestion of lactose is diagnosed.

  • Stool acidity test. This test is used in infants and young children. It measures the amount of acid in the stool. Lactic acid and glucose, made by undigested lactose, and other fatty acids can be found in a stool sample.

What is the treatment for lactose intolerance?

Your child’s health care provider will figure out the best treatment based on:

  • How old your child is

  • His or her overall health and medical history

  • How sick he or she is

  • How well your child can handle specific medications, procedures, or therapies

  • How long the condition is expected to last

  • Your opinion or preference

Although, there is not a treatment to improve the body's ability to make lactase, symptoms of lactose intolerance can often be controlled with a diet limited in lactose. In addition, your child's health care provider may recommend lactase enzymes. These are available over the counter.

Guidelines from the American Academy of Pediatrics (AAP) support the use of dairy foods as an important source of calcium for bone growth and maintenance, as well as of other nutrients needed for growth in children and teens.

In the past, it had been recommended that dairy products should be eliminated from the diet to treat lactose intolerance. The new guidelines suggest that dairy foods should be tried to see which ones a child can handle better than others. While the symptoms of lactose intolerance can be unpleasant, the condition does not hurt the body. Experts recommend that children and teens eat dairy foods that cause fewer symptoms to be sure the child gets enough calcium and other important nutrients.

How can children with lactose intolerance get enough calcium?

Calcium is needed for the growth and repair of bones throughout life and has been suggested as a preventive measure for other diseases. Because milk and other dairy products are a big source of calcium, it's important for teens to get enough calcium in a diet that includes little or no milk.

The dietary recommended intake (RDI) values for calcium vary by age group:

  • 0 to 6 months, 200 mg

  • 6 months to 1 year, 260 mg

  • 1 to 3 years, 700 mg

  • 4 to 8 years, 1,000 mg

  • 9 to 18 years, 1,300 mg

Many non-dairy foods are high in calcium, including:

  • Green vegetables, such as collard greens, turnip greens, broccoli, and kale (Swiss chard, spinach, and rhubarb are not listed because the body cannot use their calcium content--they contain substances called oxalates, which inhibit calcium absorption.)

  • Fish with soft, edible bones, such as salmon and sardines

  • Yogurt with active cultures may be a good source of calcium for many people with lactose intolerance --  the bacterial cultures used in making yogurt produce some of the lactase enzyme needed for proper digestion

Your child's health care provider may prescribe a calcium supplement if your child is not able to get enough calcium from his or her diet.

Vitamin D is needed for the body to absorb calcium. Your child's diet should have enough supply of vitamin D. Sources of vitamin D include eggs and liver. The American Academy of Pediatrics recommends that children younger than 1 year of age get vitamin D supplementation of 400 IU/day. Children over age 1 should get 600 IU/day of vitamin D supplementation. Ask your child's health care provider for advice vitamin D supplementation.

Medical Reviewers:

  • Freeborn, Donna, PhD, CNM, FNP
  • MMI board-certified, academically affiliated clinician