I am pediatrician specializing in the area of preventive cardiology, nutrition, and epidemiology, and I read with interest the recent article by Wyshak,1 which concluded that soda (especially cola) consumption by teenaged girls increased their risk of bone fractures. While I believe this is an important area of research, there are methodologic problems with this study that call into question the author's conclusions.
I am concerned that Dr Wyshak's study included no data on either bone density or dietary calcium intake for the adolescent girls surveyed. Since such data are lacking, we have no way of knowing if the bone fractures reported were associated with lower bone density, lower dietary intake of calcium, or both. It is known, for example, that girls who sustain forearm fractures tend to have lower bone density throughout the skeleton2 and that dietary calcium intake in adolescent girls correlates strongly with total body and spinal bone density.3 Thus, in any epidemiologic study of bone fracture in children, an assessment of the status of these major contributing variables seems essential.