Lactose intolerance

What is lactose intolerance?

Lactose intolerance is a condition caused by a lack of an enzyme called lactase. Inadequate amounts of lactase cause the body to be unable to digest lactose, a sugar found in milk products.

Lactase is normally produced in 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 exhibit the symptoms are said to be lactose intolerant.

Thirty to 50 million Americans (adults and children) are lactose intolerant. The disorder affects some populations more than others:

  • 75% of all African-Americans and Native Americans are lactose intolerant
  • Ninety percent of Asian-Americans are 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 produced and is the usual cause of lactose intolerance in young children. However, most cases of lactose intolerance develop over a period of many years in adolescents and adults.

What are the symptoms of lactose intolerance?

The following are the most common symptoms for lactose intolerance. However, each individual may experience symptoms differently. Common symptoms, which begin about 30 minutes to two hours after consuming foods or beverages containing lactose, may include:

  • Nausea
  • Cramps
  • Bloating
  • Gas
  • Diarrhea

The severity of symptoms varies depending on the amount of lactose consumed and the amount each individual can tolerate.

The symptoms of lactose intolerance may resemble other conditions or medical problems. Always consult your child's physician for a diagnosis.

How is lactose intolerance diagnosed?

The most common diagnostic tests (performed on an outpatient basis at the hospital, clinic, or physician's office) used to measure the absorption of lactose in the digestive system include the following:

  • Lactose tolerance test - This test measures the absorption of lactose in the digestive system. After fasting, the patient drinks a liquid that contains lactose. The diarrheal stools are then tested for lactose for the next 24 hours.
    Undigested lactose fermented by bacteria in the colon creates lactic acid and other fatty acids, which can be detected in a stool sample, along with glucose as a result of unabsorbed lactose.
  • Hydrogen breath test - The patient drinks a lactose-heavy beverage. The breath is then analyzed at regular intervals to measure the amount of hydrogen. Undigested lactose in the colon is fermented by bacteria, resulting in the production of various gases, including hydrogen. When high levels of hydrogen are present in the breath, improper digestion of lactose is diagnosed.

Treatment for lactose intolerance:

Specific treatment for lactose intolerance will be determined by your child's physician based on:

  • Your child's age, overall health and medical history
  • The extent of the disease
  • Your child's tolerance for specific medications, procedures or therapies
  • The expectations for the course of the disease
  • Your opinion or preference

Although there is not a treatment to improve the body's ability to produce lactase, symptoms caused by lactose intolerance can often be controlled with a proper diet. In addition, lactase enzymes may be suggested by your child's physician.

Calcium for children with lactose intolerance:

Calcium is essential 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 major source of calcium, parents must be concerned with lactose intolerant children and teenagers getting enough calcium in a diet that includes little or no milk.

The recommended daily dietary allowance (RDA) for calcium, released in 1997 by the National Institutes of Medicine, varies by age group.

  • 0 to 6 months - 210 mg
  • 6 months to 1 year - 270 mg
  • 1 to 3 years - 500 mg
  • 4 to 8 years - 800 mg
  • 9 to 18 years - 1,300 mg

Many nondairy foods are high in calcium, including:

  • Green vegetables, such as 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 - evidence shows that the bacterial cultures used in making yogurt produce some of the lactase enzyme required for proper digestion.

Your child's physician may prescribe a calcium supplement if your child is unable to get enough calcium from their diet.

Vitamin D is necessary for the body to absorb calcium, therefore, your child's diet should provide an adequate supply of vitamin D. Sources of vitamin D include eggs and liver. Sunlight is also a good source of vitamin D.