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ELK GROVE, Ill., Feb. 6 - Most U.S. children don't get enough calcium in their diets, and pediatricians should intervene to help remedy the problem, according to guidelines issued today by the American Academy of Pediatrics.

The proportion of children who receive the recommended amounts of calcium declines dramatically after the second year of life, reaching a nadir during adolescence, said Nancy F. Krebs, M.D., of the University of Colorado in Denver, who headed the academy committee that wrote the guidelines.

Adolescent girls are faring the worst, Dr. Krebs and colleagues reported. Only about 10% of girls ages 12 to 19 are getting the recommended amount of calcium. For boys, the figure is about 30%, according to the guidelines, which were published in the February issue of Pediatrics.

About 80% of children ages one to two receive enough calcium. For children age three to five, the figure falls to less than 60%. For children six to 11, it drops further to less than 40% for boys and less than 30% for girls.

The figures are especially troubling, the authors said, because calcium accretion reaches its peak during adolescence, a time during which 40% of total lifetime bone mass is accumulated. Children who don't get enough calcium are at increased risk of bone fractures during adolescence and osteoporosis later in life, the guidelines said.

The guidelines provided a food intake questionnaire and a chart of the calcium content of some common foods. These, said Dr. Krebs and colleagues, should be used to assess a child's dietary calcium intake at two to three years of age (once the child has made the transition from human milk or formula), again at age eight or nine during preadolescence, and once more during adolescence, the authors said.

Pediatricians should give information on the calcium content of common foods to patients and families for whom calcium intake is not adequate, said the guidelines. Pediatricians should also stress the value of physical activity, especially weight-bearing exercise, for developing strong bones. Adequate vitamin D intake (200 IU or 5 mcg per day for children and adolescents) should also be advised, the guidelines said.

Generally, parents and children can be advised that three daily servings of low fat dairy products (yogurt, cheese, flavored milks)-and four daily servings for adolescents-is enough to ensure adequate calcium intake, the authors said.

Several products have been introduced that are fortified with calcium. Orange and apple juice may be fortified to achieve a calcium concentration similar to that of milk. Breakfast cereals also are frequently fortified with minerals, including calcium, A soy beverage, unless fortified with calcium, is not a good source, because the bioavailability of calcium is low.

If one relies on calcium-fortified foods or nondairy foods that are low in vitamin D, then another source of vitamin D is needed to

provide the adequate intake of 200 IU per day. Orange juice can also be fortified with vitamin D in addition to calcium.

One reasons for low calcium intake among children and adolescents may be that milk is replaced by soft drinks as the beverage of choice, the authors suggested.

"Inadequate calcium intake in a child or adolescent is a family problem," they said. "If the parent is not achieving the recommended calcium intake, it is unlikely that the child is achieving the recommended intake."

The guidelines included the following recommend daily calcium intakes for various age groups:

• 0-6 months: 210 mg
• 7-12 months: 270 mg
• 1-3 years: 500 mg
• 4-8 years: 800 mg
• 9-18 years: 1,300 mg
• 9-50 years 1,000 mg
• 50-70 years: 1,200 mg

For children and adolescents who can not or will not consume adequate amounts of calcium from preferred dietary sources, the use of calcium supplements should be considered, the authors recommended.

"Although the bioavailability of calcium varies in supplements, it may be comparable to or greater than that in dairy products," they said.

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