Sodas Linked to Girls' Bone Fractures
Health: Highest risk is found among physically active teenagers who drink colas. Many welcome report as an alert, but skeptics point to study's shortcomings.
By ROSIE MESTEL, Times Medical Writer
Nobody ever claimed that soda pop is health food. But now a Harvard University scientist reports that teenage girls who drink sodas have a higher risk of bone fracture than girls who do not and that physically active girls who drink cola beverages have the highest fracture rate.
The study, published today in the Archives of Pediatric and Adolescent Medicine, does not establish a cause-and-effect relationship between drinking sodas and sustaining fractures, experts said. It lacks many details scientists would like to see, they added.
Despite these limitations, the finding shouldn't be ignored, they said. It speaks to a concern many health professionals have: that girls in particular aren't getting enough calcium in their diet; that they're drinking soft drinks instead of milk; and that insufficient calcium intake is heightening their risk in later life for thin, fragile bones that break more easily.
To try to get girls on track, a multimillion-dollar effort--the National Bone Health Campaign, sponsored by the Office on Women's Health in the Department of Health and Human Services, the Centers for Disease Control and Prevention and the nonprofit National Osteoporosis Foundation--will be launched in February.
It will initially target girls ages 9 to 12, parents and teachers via print, TV and radio ads, stressing the importance of getting adequate calcium while bones are still maturing, as well as of regular, weight-bearing exercise, which also helps build bone.
"We can see from the statistics that young girls are not consuming enough calcium-containing products," said Dr. Saralyn Mark, senior medical advisor for the Office on Women's Health and NASA. "We can interpret that to mean that we're going to have a generation of people with thin bones at risk for developing osteoporosis. The cost to the country--in terms of dollars and quality of life--will be significant."
Adequate calcium intake is essential for developing healthy bone. Bones reach their peak of strength and density in young adulthood, declining thereafter. Just as people sock money away for retirement, bone specialists say it's important to build up bone in early life to lower a later risk for osteoporosis, which affects women especially.
However, "most Americans aren't coming close to the recommendations for how much calcium they need daily. And adolescent girls are really at a deficit," said Molly Natchipolsky of the National Osteoporosis Foundation in Washington, DC.
In a recent government survey of the foods Americans eat, only 13% of girls ages 12 to 19 were getting their recommended 1,300 milligrams of calcium daily.
The carbonated beverage study was conducted by Grace Wyshak, an associate professor and biostatistician in the Harvard Medical School and Harvard School of Public Health. In it, 460 ninth- and 10th-grade schoolgirls filled out a questionnaire about their soda-drinking habits, as well as their participation in sport programs, and whether they had ever fractured a bone.
Analyzing the data, Wyshak found that girls who reported drinking carbonated beverages also reported, as a group, three times as many bone fractures as the group that did not drink sodas. Girls who described their level of physical activity as either "high level" or "vigorous" and who drank colas, specifically, had a fracture rate five times higher than physically active girls who didn't drink cola.
The girls didn't report how many sodas they drank or whether their sodas were caffeinated. Wyshak detected no difference between diet and regular sodas.
Wyshak offered two explanations for her finding, which builds on two previous papers she has written on this topic.
It's possible, she said, that the phosphoric acid in colas is weakening bone somehow by interfering with the body's ability to absorb and use calcium. (Cola beverages contain phosphoric acid, but other sodas generally don't.) However, in a report issued last year, the National Academy of Sciences concluded that there is no evidence that phosphorus levels in the U.S. diet are sufficient to adversely affect bone health.
Alternatively, girls could be consuming less milk because they're drinking more soda, Wyshak said. According to statistics from the U.S. Department of Agriculture, the per capita consumption of milk declined 23% between 1970 and 1997, while consumption of carbonated soft drinks increased 118%.
Either way, she said, "I think these findings have tremendous public health implications. I think people should be aware of the risk and be prudent."
The paper is alarming and "brings up important questions that ought to be subjected to rigorous scientific study," said Dr. Neville H. Golden, co-director of the Eating Disorders Center at Schneider Children's Hospital of the Long Island Jewish Medical Center. But the study would have been stronger, he said, if data had also been collected on how much soda the girls drank, how much milk they drank, and whether the exercise they engaged in was weight-bearing, such as running or tennis, which tends to build bone. The fractures should also have been verified through medical records.
Ideally, a study would also measure the girls' bone mineral density--a measure of the toughness of bone--and would track girls through time to see what happened to the skeletons of the soda drinkers. As it is, Golden said, the findings are important but limited.
"A fivefold increase in risk sounds unlikely--it sounds too high," said Dr. Frederick Singer, clinical professor of medicine at UCLA and director of the Bone Disease Program at the John Wayne Cancer Institute in Santa Monica. He, like many other bone specialists and pediatricians, said he is concerned by young children's inadequate calcium intake and over-consumption of sodas.
He'd more readily accept this study's results, he said, if the subjects were anorexic girls, who develop "shockingly low" bone densities. But normal, cola-drinking girls? "It's hard to understand that much risk," he said. "That would raise a flag that this is some sort of aberration."
Responding to the study, the National Soft Drink Assn., which represents 95% of the country's soft drink producers, marketers and distributors, released a statement challenging Wyshak to "reexamine her work." Association spokesman Richard Adamson termed the study "nutritional nonsense."
The association rebutted both the theory that phosphoric acid in drinks could weaken bone and the suggestion that soft drinks are replacing milk. It cites the National Academy of Sciences report and one from the National Institutes of Health, concluding that the amounts of phosphorus in today's foods are unlikely to affect bone.
It also cites two studies--one funded by The Sugar Assn., a sugar industry trade group, the other funded by a mix of government and industry sources--that suggest dairy intake in children is not being supplanted by sugary foods or sodas.
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Age group: 9 to 18-year-olds
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Some Calicium-Rich Foods
Food Serving size Calcium (mg)MilkWhole
8 oz. 2901 % 8 oz.
2% 8 oz. 297
Skim 8 oz. 302
YogurtPlain, fat-free 8 oz. 487
Fruit, low-fat 8 oz. 338
Frozen, vanilla 1/2 cup 103
CheeseAmerican 1 oz. 174
Cheddar 1 oz. 204
Cottage 1 cup 138
FishSalmon, 3 oz. 181
pink, canned with bonesShrimp, canned 3 oz. 50
Cooked vegetablesBroccoli, fresh 1 cup 72
Broccoli, frozen 1 cup 94
Navel orange 1 56
Orange juice, 8 oz. 300
calcium-fortifiedSesame seeds 1 oz. 37
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Sources: National Osteoporosis Foundation, National Academy of Sciences