Richard Colletti, MD

Building strong, healthy bones requires calcium. Approximately 90 percent of adult bone mass (strength and density) accumulates between the ages of 9 and 18. To support healthy bone growth kids need 1,300 milligrams (mg) of calcium each day.

The National Institutes of Health recommends (low or non-fat) milk and milk products, such as yogurt and cheese, as excellent sources of calcium. Most dairy foods have approximately 300 mg of calcium per serving (8 fluid ounces or 1 cup). This represents 25 percent of the recommended daily value of 1,300 mg. Thus, providing four servings of milk or milk products daily will deliver the calcium necessary to develop strong, healthy bones.

It sounds simple enough, but what if a child has trouble digesting lactose, the natural sugar found in dairy? This is called lactose intolerance. Lactose intolerance is characterized by difficulty or inability to digest lactose because of an inadequate amount of lactase (the enzyme that breaks down lactose).

Children with Crohn's disease or ulcerative colitis are generally no more likely than other children to have lactose intolerance. Those children with Crohn's disease affecting a large part of their small intestine may be at increased risk. A breath hydrogen test can diagnose lactose intolerance.

Clinical symptoms of lactose intolerance include stomach pain, diarrhea, bloating and gas. The severity of symptoms may vary depending on the amount of lactase that is in the body and how much lactose is consumed. Some people with lactase deficiency can still consume a small amount of lactose (in 8 to 12 ounces or 1 to 1 ½ cups of milk) without experiencing symptoms.

The National Institutes of Health reports the following dietary strategies can help people with lactose intolerance get enough calcium in their diet, while minimizing symptoms of lactose intolerance:

* Drink milk in servings of 1 cup or less.

* Drink milk accompanied by food, such as breakfast cereal.

* Eat hard cheeses (such as Swiss, cheddar or provolone) or yogurt. These foods contain a lower amount of lactose per serving compared with milk and may cause fewer symptoms.

* Buy special lactose-free milk and other lactose-free milk products, which have an equivalent amount of calcium as regular milk.

* Use over-the-counter pills or drops that contain lactase, which can eliminate symptoms altogether.

* Consume calcium-fortified foods that have no lactose, such as orange juice with added calcium, soy beverages with added calcium, and some fortified breads and breakfast cereals.

It is important to note that lactose intolerance is not the same thing as a milk allergy. A milk allergy is related to the proteins in milk rather than the sugar lactose.