The condition is relatively rare in whites, but as many as 75 percent of blacks, 90 percent of Asian-Americans and nearly 100 percent of Native Americans suffer from it. Symptoms generally start appearing after the age of 2.
When symptoms do appear, the first step should be to make sure that they are not caused by another condition, such as irritable bowel syndrome, celiac disease, an infection or parasites, Heyman said.
If lactose intolerance is the problem, it's important to remember that the condition does not do bodily damage, however unpleasant the symptoms might be, he said. Careful testing can help determine which products affect an individual and which are a lesser problem. "Some people might tolerate yogurt but have problems with milk," Heyman said.
The important point is that young people get an adequate amount of calcium, he said. The guidelines note that the National Medical Association, an organization of black physicians, "recently recommended that black people consume three to four servings a day of low-fat milk, cheese and/or yogurt."
"If lactose-free diets are used for treatment of lactose intolerance, the diets should include a good source of calcium and/or calcium supplementation to meet daily recommended intake levels," the guidelines state.