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Lactose intolerance in children

Children's Hospital Boston specialists Richard Grand, MD, director of the General Clinical Research Center and the Center for Inflammatory Bowel Disease, Christopher Duggan, MD, MPH, director of the Clinical Nutrition Service, and Catherine Gordon, MD, director of Children's Bone Health Program, discuss lactose intolerance and the American Academy of Pediatrics' new recommendations.

Why is the use of dairy by lactose intolerant children beneficial?
Dr. Grand: Nutritionists recommend that lactose intolerant children consume dairy because it's rich in calcium, protein and vitamin D. Lactose intolerance is not a food allergy, in which a person might suffer a dangerous reaction, but a symptom that can grow or decrease in severity according to how much lactose a child consumes. Symptoms of intolerance can be alleviated by reintroducing dairy into the diet in small quantities. This allows the bacteria in the colon to adapt to the increasing carbohydrate load by digesting what was not digested in the small intestine.

Are many babies thought to be lactose intolerant when they really have an allergy to cow's milk proteins?
Dr. Grand: Yes. Almost all infants can tolerate lactose, as it is in breast milk and formulas.

Which age group typically suffers from lactose intolerance?
Dr. Grand: The age at which lactase levels fall is variable among ethnic groups, but is typically between ages 2 and 18. Almost no one develops intolerance before age 2. In the United States, in those people who will develop low lactase levels, drop typically occurs between ages 5 and 7. Natural levels of the lactase enzyme decrease during the mid-childhood years. However, many children maintain lactase activity throughout life.

What does the occurrence depend on?
Dr. Grand: Factors such as fat content of the food, rate of stomach emptying, sensitivity to intestinal distension and the response of the colon to the carbohydrate load. People of certain ethnic backgrounds, including Asians, Hispanics and African-Americans, are more likely to suffer from lactose intolerance in childhood than those of Northern European decent.

How is lactose intolerance diagnosed?
Dr. Duggan: Strict dietary avoidance of lactose and follow-up of symptom resolution is one way to diagnosis lactose intolerance. It can also be more precisely diagnosed with a lactose breath hydrogen test: The patient drinks lactose after fasting for eight hours and the level of hydrogen in his or her breath is measured with a gas chromatograph. Elevated levels of expired breath hydrogen can confirm lactose malabsorption.

Should a patient's diet ever be restricted?
Dr. Duggan: No child should be placed on a restricted diet unless under the supervision of a registered dietitian and/or physician. Child growth and development are contingent upon a diet with a wide variety of vitamins, minerals (so-called micronutrients) as well as carbohydrates, fats and proteins (macronutrients). If a restricted diet for lactose malabsorption is prescribed, a dietitian can identify alternatives and ensure that necessary nutrients remain in the diet. For example, many fortified orange juices have as much calcium as milk.

Dr. Grand: A treatment plan should include only short-term lactose restriction. Then, lactose should be increased gradually. If a child shows extreme discomfort, then alternative sources of calcium and vitamin D should be incorporated into the child's diet. It's important that the child still consume the proper amount of protein and fat.

Is limited consumption of vitamin D a related concern?
Dr. Duggan: Yes. Vitamin D deficiency is a major public health concern because of decreased sun exposure and low dietary intake in children and adolescents. Something that's even less widely known is that infants who are breastfeeding don't receive the recommended levels of vitamin D and should receive a supplement in the form of a multivitamin. In fact, there have been increasing reports of vitamin D deficiency rickets in American infants, especially among breastfed African-American babies.

Dr. Gordon: With greater awareness about both lactose intolerance and milk allergy, more infants and toddlers are drinking soy milk, rice milk and other milk substitutes that lack vitamin D. Sunlight can be an excellent source of vitamin D, but in New England and other high latitude locations, sun exposure is precluded much of the time from November through February.

Is there research that points to lower bone density in children who aren't consuming lactose?
Dr. Gordon: There are no conclusive studies regarding lactose and bone acquisition. However, there are studies that link milk consumption during childhood to fewer fractures and higher bone density during adulthood. These studies, carried out in healthy, non-lactose intolerant children and adults, have caused us to worry about inadequate calcium and vitamin D intake among children with lactose intolerance.

Can non-dairy foods help foster healthy bone development?
Dr. Gordon: Yes. Unfortunately, many calcium-rich foods happen to be those that many children refuse to eat, such as kelp, kale and broccoli. Also, a large serving of these foods is required to achieve the recommended daily allowance. Aside from fortified milk, few foods provide enough vitamin D. Exceptions are fatty fish, fish oils and some fortified cereals.

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