US youngsters are deficient in both for several reasons: They drink sodas instead of milk or calcium-fortified juice; they're spending more time on TV, computers and video games instead of exercising; and many schools have phased out organized physical activities.

National data show that most American children over age 8 don't get enough calcium, a deficiency that increases their risks for developing osteoporosis in adulthood, the academy said in a report released Monday in the journal Pediatrics.

The bone-thinning disease is associated with aging and afflicts 10 million Americans, mostly older women. National data show it is responsible for more than 1.5 million bone fractures each year.

There's also evidence suggesting that fractures may be on the rise in US adolescents, perhaps because calcium-deficient diets and little exercise already have weakened their bones even if they haven't yet developed osteoporosis, said Dr. Craig B. Langman, who treats pediatric bone problems at Chicago's Children's Memorial Hospital.

Weight-Bearing Activity Critical

"We really should be having more recommendations to pediatricians to think about long-term bone health in kids. This is an excellent first step in doing that," said Langman, who was not involved in the report.

Calcium is needed for bone formation, and weight-bearing exercise strengthens bones. For children, it could include soccer, basketball, football, running -- essentially any repetitive activity in which the arms or legs bear the body's weight.

"You can take all the calcium you want, but if you don't do any weight-bearing activity, you don't have good bone health," said report co-author Dr. Frank Greer, a member of the academy's nutrition committee and pediatrics professor at the University of Wisconsin.

US youngsters are deficient in both for several reasons, Greer said: They drink sodas instead of milk or calcium-fortified juice; they're spending more time on TV, computers and video games instead of exercising; and many schools have phased out organized physical activities.

Milk and other dairy products are the most common calcium sources in traditional Western diets, but there's no evidence that they are superior to other sources, such as broccoli, Swiss chard and collard greens, the report said. Still, children tend to avoid those, too, Greer said.

Vitamin D Deficient Too

The Pediatrics report recommends doctors screen for calcium intake and bone health three times during childhood: at age 2 to 3 after weaning from breast milk or formula; at age 8 to 9, before the adolescent growth spurt; and again during puberty or teen years, when the peak rate of bone mass growth occurs.

Screening can include simple questions about diet, milk consumption, amount of exercise, bone fractures and family history of osteoporosis, the report said.

The report includes sample questions and recommendations for daily calcium intake at various ages. It comes three years after the academy issued guidelines for vitamin D, which is needed to help the body absorb calcium. The 2003 guidelines recommend vitamin D supplements for babies who only get breast-milk and older children at risk for deficiency.

Many US youngsters are vitamin D deficient too because they don't drink vitamin D-fortified milk and lack adequate exposure -- without sunscreen -- to sunlight, which is needed for the body to produce the vitamin. Doctors say only 10 to 15 minutes of sun exposure weekly is needed for adequate vitamin D production.