School soft drink intervention study

The paper by James et al in this issue of BMJ USA (p 410) describes the results of a five-session, classroom-based educational curriculum on changes in body mass index (BMI), over-weight prevalence, and carbonated beverage consumption among 7- to 11-year-old children in six schools. After one year, a significant difference between intervention and control groups was observed for change in prevalence of overweight. Total carbonated beverage intake did not significantly change among children in the control classrooms, but a significant decrease was observed among children in the intervention classrooms.

No single study can provide irrefutable evidence linking soft drink consumption and obesity among children. While this paper provides some intriguing findings that warrant further exploration in follow-up studies, several notable methodological limitations cloud the interpretation of the findings and prevent firm conclusions from being drawn.

Conceptually, perhaps the most important limitation is the absence of a mediational analysis that specifically links changes in soft drink consumption to changes in obesity prevalence.1 The …