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 and milk products.
Lactase is normally produced 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 exhibit the symptoms are said to be lactose intolerant.
The disorder affects some populations 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.
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.
The following are the most common symptoms for lactose intolerance. However, each individual may experience symptoms differently. Symptoms begin to appear in Caucasian children after age five, and in African-American children as early as two years of age. Common symptoms, which begin about 30 minutes to two hours after consuming foods or beverages containing lactose, may include:
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 doctor for a diagnosis.
The most common diagnostic tests (performed on an outpatient basis at the hospital, clinic, or doctor'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.
Stool acidity test. This test, used in infants and young children, measures the amount of acid in the stool. Lactic acid and glucose, produced by undigested lactose, and other fatty acids can be detected in a stool sample.
Specific treatment for lactose intolerance will be determined by your child's doctor 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 diet limited in lactose. In addition, lactase enzymes (available over the counter) may be suggested by your child's doctor.
In September of 2006, the American Academy of Pediatrics released new guidelines for treating lactose intolerance. These guidelines 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 adolescents.
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 can be tolerated better than others. While the symptoms of lactose intolerance can be unpleasant, the condition does not damage the body. Thus, dairy foods that cause less disagreeable symptoms should be used in the diet to ensure adequate intake of calcium and other important nutrients.
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 dietary recommended intake (RDI) values for calcium vary by age group:
Many nondairy 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--evidence shows that the bacterial cultures used in making yogurt produce some of the lactase enzyme required for proper digestion
Your child's doctor may prescribe a calcium supplement if your child is unable to get enough calcium from his or her 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. The Institute of Medicine (IOM) recommends that children younger than 1 year of age receive vitamin D supplementation of 400 IU/day. Children over age 1 should receive 600 IU/day of vitamin D supplementation.