Carbonated Drinks and Bone Fractures

E-Newsletter No. 10

To determine the possible association between carbonated beverage consumption and bone fractures among teenaged girls, Wyshak, et al, (Arch. Pediatr Adolesc Med 2000; 154:610-613), conducted a cross-sectional (retrospective) study in an urban high school.

Four hundred sixty 9^th and 10^th grade girls participated in this study by completing a self-administered questionnaire relating to their physical activities and personal and behavioral practices. The school system and the Harvard School of Public Health Institutional Review Board approved the study. The girls’ self-reports on physical activity, carbonated beverage consumption, and bone fractures were analyzed.

In the total sample, carbonated beverage consumption and bone fractures are associated: odds ratio (OR)=3.14 (95% confidence interval [CI], 1.45, 6.78), P=0.004. Among physically active girls, the cola beverages are highly associated with bone fracture: OR-4.94 (95% CI, 1.79, 13.62), P=0.002.

The results confirm previous findings, but the mechanism by which cola drinks are associated with bone fractures in physically active girls has neither been fully explored nor determined. Nevertheless, national concern and alarm about the health impact of carbonated beverage consumption on teenaged girls is supported by the findings of this study. The results have policy implications for improving the dietary practices and health of children.

Comment
Published amidst the hubbub of the holiday season late last year, this study’s relevance surfaces just in time for summer. The National Soft Drink Association didn’t like it one bit—and a subsequent letter to the editor faults Wyshak’s methods, results, and conclusions.

Harvard School of Public Health author and researcher Wyshak didn’t back down. She writes: "Calcium and calcium supplementation have been found to increase bone mineral density. Osteoporotic fractures may be affected by diet and activity among young women. Adolescence could be a critical period for bone mass formation; adolescent females at the time of puberty may be the optimal population for early prevention of osteoporosis with calcium intake.

It’s hard to take issue with such carefully collected data and confirmation of earlier findings. Indeed these self-administered questionnaires—with internal consistency and face validity—can only give associative data. It can’t be stated that cola drinks cause fractures in active teenaged girls.

But it can be stated that most colas contain 11 teaspoons of sugar per 12 ounce can. And that other than calories from sugar, cola contain virtually no nutrients. Carbonated beverages deplete calcium from bones, and can cause hypocalcimia, actually resulting in reported tetany (unrelenting muscle spasms). Whether the mechanism lies in the phosphoric acid, caffeine content, displacement of other nutrients, or the excess simple sugar in soda, no one knows. What we do know is that colas are not good food, and that they are bad medicine.

Recommendation:
To quench thirst, drink water, not soda. Discourage teenaged girls from drinking soda---- it provides only empty calories and is associated with increase fracture risk.

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