CHICAGO (AP) - Teen-age girls who drink soda - particularly cola - are far more likely to break a bone, a Harvard study found.

Grace Wyshak, an associate professor at the Harvard School of Public Health and Harvard Medical School, speculated that girls drinking soda aren't getting enough milk, which contains calcium that strengthens bones.

But she also suggested that a chemical in colas - phosphoric acid - may actually weaken bones.

The study, published in this month's Archives of Pediatrics & Adolescent Medicine, was based on questionnaires filled out by 460 ninth- and 10th-grade girls in a Boston-area high school.

The risk of broken bones was three times greater for girls who drank carbonated beverages in general and five times greater for active girls who drank colas. The study did not specify how much soda the girls drank.

Five of the 57 active girls who didn't drink colas suffered fractures, compared with 38 of the 107 active girls who reported drinking colas.

A spokesman for the National Soft Drink Association, Sean McBride, said: "We strongly question the results of the journal article." He said there is no scientific evidence that anything in colas causes fractures.

The study comes amid growing concern among experts, who say Americans are not getting nearly as much calcium as they need, in part because they are drinking soft drinks instead of milk.

"This should be a wake-up call for parents and health care professionals alike," said Bonnie Liebman, director of nutrition at the Center For Science in the Public Interest, a consumer advocacy group.

In an accompanying editorial, Dr. Neville H. Golden, director of the Eating Disorders Center in the Division of Adolescent Medicine at Schneider Children's Hospital in New Hyde Park, N.Y., said the study suggests that "osteoporosis is a pediatric disease as opposed to a disease of older people and that we can have some impact on it early."

In a previous study, Wyshak found increased bone fractures among adult women who drank carbonated beverages.

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