Although some children are lactose intolerant from birth -- usually due to genetic problems -- this condition is more likely to develop as children get older. An enzyme in the small intestine called lactase gradually diminishes as people age, which can cause symptoms of lactose intolerance in teens who were able to drink milk and eat cheese in their younger years.
Lactose and Lactase
Lactase is the enzyme that breaks down a sugar called lactose, found in milk and other dairy products. Without adequate lactase in the intestine, the undigested lactose sugars sit in the intestine and eventually begin to break down due to bacterial action, which causes a lot of undesirable effects such as cramps, diarrhea and gas. Lactose intolerance can have a genetic component. Asian and Native American teens are almost always lactose intolerant, and TeensHealth reports that up to 80 percent of African American and Hispanic American teens also have this problem.
Calcium and Bone Mass
One of the major concerns with lactose intolerance is that a teen is developing the bone mass she will need for the rest of her life. Calcium deficiency during the teen years can cause osteoporosis in middle age. Teens need at least 1,300 milligrams of calcium a day, and many teens tend to have diets that are deficient in calcium even when they aren’t lactose intolerant, according to the National Institute of Child Health and Development. Teens who are lactose intolerant should continue to eat some dairy foods if possible, because the need for calcium is so important.
Lactose-free and lactose-reduced milks are available, and many foods have calcium added. When foods with dairy are combined with nondairy foods, they may be easier to digest. Broccoli, beans, tofu and spinach contain calcium, but in lower amounts than dairy products, and it’s more difficult for your teen’s body to absorb the calcium in these foods. Your teen could try keeping a food diary to see whether there are some dairy foods she can tolerate. Cheese and yogurt, for example, may be easier for her to digest.
The NICHD reports that even teens with lactose intolerance can usually drink 8 to 12 ounces of milk, especially if they add other foods such as cereal or a sandwich. Teens may go through phases when they avoid certain foods, but a teen with lactose intolerance is more likely to complain that the foods make her sick or uncomfortable. Doctors diagnose lactose intolerance based on your child’s symptoms and a physical examination. The American Academy of Pediatrics reports that teens with lactose intolerance don’t usually need treatment, but if you have questions or concerns, talk to your family doctor or pediatrician.