Even More on Calcium

Good health starts with good nutrition. Good nutrition can protect against disease later in life. The Food Guide Pyramid, and the Dietary Guidelines for Americans, are national recommendations to help people choose diets that promote health and reduce disease risks. A healthy diet should include food from the major food groups: grains (bread, cereal, rice, and pasta); vegetables; fruits; dairy products; meat (poultry, fish, dry beans, eggs and nuts). Fats and oils, located at the top of the food pyramid, should be used sparingly.

Recent studies show that few American children are meeting all of the recommendations outlined in the food pyramid. Teenage girls, on average, failed to meet any of them. One essential nutrient lacking in the diets of many children and teens is calcium, found primarily in dairy products and in dark, leafy green vegetables. Calcium plays a role in the proper functioning of the heart, muscles and nerves and in maintaining blood flow. But most calcium is used in building bone mass in order to support physical activity throughout life and to reduce the risk of bone fracture, especially that due to osteoporosis, the weakening of bone that can occur late in adulthood.

Building Strong Bones
Though they appear hard, rigid, and lifeless, bones are actually growing and alive. Exercise and adequate calcium both influence bone mass. Weight-bearing exercise, such as dancing, weight-lifting, or running, determines bone mass, shape, and strength. Smoking, unhealthy eating patterns, and alcohol use detract from bone mass. Excessive salt intake may increase the amount of calcium lost in the urine, and therefore, increase the body’s need for calcium.

Scientists agree that diets deficient in calcium during childhood and adolescence contribute to the development of osteoporosis, which is not visible until late in life. A positive calcium balance – taking in more than is lost throughout childhood, adolescence, and young adulthood – will allow bones to develop to their maximum density. But it is during the teen years that optimal calcium intake is most important. Bones grow and incorporate calcium most rapidly then. Soon after, by the age of 17, approximately 90% of the adult bone mass will be established. By the age of 21 or soon after, calcium is no longer added to bones and a few years later, a steady process of loss of calcium from bones begins. Genetically, people differ in how much calcium is in their bones when they reach maturity, but how much calcium they eat while they are growing has an important influence. The more calcium that is in the bones when loss begins, the longer it will take before the bones become fragile and fracture easily.

No Bones About it, Kids and Teens Can’t Do Without It
Research sponsored by the National Institute of Child Health and Human Development (NICHD) has shown that a "window of opportunity" exists to add to the bone bank during the teen years. NICHD researchers have found that supplementing the daily diets of girls, ages 12 to 16, with an extra 350 mg of calcium, produced a 14% increase in their bone density, in comparison to unsupplemented girls. If this 14% increase in their bone density could be maintained, its impact would be striking.

For every 5% increase in bone density, the risk of later bone fracture declines by 40%. It is becoming increasingly evident that adequate calcium intake is critical during adolescent years.

Kids and Calcium: How Much Do They Need?
The new federal calcium guidelines, the Dietary Reference Intakes, recommend that children ages 4-8 get 800 mg of calcium per day, or the equivalent of 2-3 glasses of low-fat milk. Adolescents and young adults, ages 9-18, whose bones are growing very fast, need more calcium. They should have 1300 mg, or about 4-5 glasses of low-fat milk per day.

Kids and Calcium:
Who Gets Enough?
Unfortunately, most children and teens do not meet dietary calcium recommendations. National nutrition surveys say that more than one-half of all children under 5 – and nearly seven-eighths of girls ages 12-19 – do not meet the 1989 federal recommendations for calcium. In fact, teenage girls only average about 800 mg of calcium per day, well below the amount needed for normal growth and development. This is especially critical since the new Dietary Reference Intakes set even higher calcium levels than the 1989 guidelines. Individuals with inadequate intake of dietary calcium may increase their risk for bone fractures and development of osteoporosis.

Where Is the Calcium?
The NICHD believes low-fat milk or low-fat milk products are the best sources of calcium because they contain large amounts of calcium, along with additional nutrients to help the body better absorb calcium. They are also already part of most American diets. Along with calcium, milk provides other essential nutrients, including vitamin D, potassium and magnesium, all essential for optimal bone health and human development. Green leafy vegetables are healthy sources of calcium too, but it takes at least 5 servings of collards a day to get the same amount of calcium that is in 3-4 glasses of milk.

Lactose Intolerance
Some parents may think that their child or teen is lactose intolerant. Lactose intolerance is the inability to properly digest lactose, a sugar found in milk and other dairy foods. Lactose intolerance results in symptoms of bloating, gas, stomach cramping and diarrhea after eating dairy products. However, most children can tolerate lactose. African-American, Mexican-American, and American Indian children and Asian Pacific Islanders are more likely than Caucasian children to be lactose intolerant. Recent studies show, however, that even children diagnosed with lactose intolerance can drink one to two cups of milk each day without suffering abdominal discomfort.

For children and teens with lactose intolerance, milk is often better tolerated when consumed with a meal. Some dairy foods, such as hard cheeses, or yogurt, contain less lactose than milk and cause fewer symptoms. In addition, lactose-reduced and lactose-free milk products are now readily available in most supermarkets. For those who cannot tolerate any milk, dietary calcium can come from non-dairy sources such as green vegetables like broccoli and spinach. Alternatively, calcium-fortified foods, such as orange juice, or calcium tablets, which provide 200-500 mg per tablet, can serve as the source of necessary calcium.

Solving the Calcium Crunch
Children and teens can get enough calcium in their daily diets by drinking 3-4 glasses of milk throughout the day, in breakfast cereal, with lunch, dinner, or as a snack. Making milk the standard and routine drink with meals throughout childhood and adolescence, and even through the adult years, is the best way to assure adequate calcium intake. For children over the age of two, low-fat or non-fat milk is recommended because it will add calcium to the diet without the fat. There are now a variety of milk products available, ranging from whole milk to non-fat or skim milk – but an 8 oz. glass of any variety still contains about 300 mg of calcium. Teens and young adults concerned about calorie intake and weight gain should know that 12 oz. of fat-free milk contains less calories than a 12 oz. soft drink, and provides 1/3 of daily calcium needs as well as many other important nutrients.

The NICHD recognizes inadequate calcium consumption among children and adolescents to be a growing problem and a serious threat to their later healthy growth and development. NICHD researchers are working to develop methods to prevent osteoporosis both through physical activity and through dietary means in childhood. Although adequate calcium benefits bones of all ages, children and teens need more calcium today to protect against bone fractures tomorrow.

Prepared by NICHD
Public Information and
Communications Branch