Calcium and Adolescents

What food source is the nutrient found in?

About 75 percent of the calcium in the American diet comes from dairy foods, such as milk, yogurt, and cheese. These foods are best because they contain high amounts of calcium. For instance, 8 ounces of milk, 1 cup of yogurt, and 1.5 ounces of cheese each contain 300 mg of calcium. They also provide other nutrients that help the body better absorb calcium, such as vitamin D, potassium, and magnesium. Dairy products are a good source of protein and riboflavin, which are needed for proper growth and development.

Vegetables, grains, and beans also provide calcium, but the calcium in these foods is not absorbed as well as the calcium in dairy foods.

Calcium may be poorly absorbed in these foods:

As a result, several servings of these foods are needed to provide the body with the same amount of calcium present in one serving of dairy products.

Extra calcium has been added to some foods. These include:

It is not known how much of this added calcium is absorbed by the body. Limited studies of calcium-fortified orange juice suggest that the absorption rate is about the same as milk.

How does the nutrient affect the body?

Calcium is needed for building healthy teeth and bones. Strong bones enable a person to stay physically active all through his or her life. It also reduces a person's risk for osteoporosis as he or she gets older.

During the teen years, physical activity and nutrition play a key role in hip development. This is the time when calcium is best absorbed and when most bones are formed. By the time a person reaches the age of 17, about 90 percent of his or her adult bone mass has been reached. To support the growth of strong bones, federal guidelines recommend that children between the ages of 9 and 18 consume 1300 mg of calcium each day. This equals more than four glasses of milk.

The gap between the amount of calcium that is recommended and the amount of calcium the typical child gets each day is large. The average child gets about 700 to 1000 mg of calcium a day, with values at the higher end of the range occurring in males. About 69 percent of the recommended calcium intake is consumed by girls, ages 9-13. Girls who are ages 14-18 consume about 55 percent of the recommended daily calcium intake. Teens may not get enough calcium because:

Another factor may be lactose intolerance. A person with lactose intolerance cannot digest lactose, the natural sugar present in milk. Symptoms after eating dairy products include:

Lactose intolerance is most common in African Americans, Mexican Americans, and Asian Americans.

Children and teens who do not consume enough calcium are not able to achieve maximal bone mass. This puts them at risk for osteoporosis, which is brittle bone disease, when they get older. Osteoporosis affects more than 25 million Americans, most of them women. There is no cure for osteoporosis, so prevention is key.