School vending machine purchasing behavior: results from the 2005 YouthStyles survey.

Background: Competitive foods are often available in school vending machines. Providing youth with access to school vending machines, and thus competitive foods, is of concern, considering the continued high prevalence of childhood obesity: competitive foods tend to be energy dense and nutrient poor and can contribute to increased energy intake in children and adolescents.

Methods: To evaluate the relationship between school vending machine purchasing behavior and school vending machine access and individual-level dietary characteristics, we used population-level YouthStyles 2005 survey data to compare nutrition-related policy and behavioral characteristics by the number of weekly vending machine purchases made by public school children and adolescents (N = 869). Odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were computed using age- and race/ethnicity-adjusted logistic regression models that were weighted on age and sex of child, annual household income, head of household age, and race/ethnicity of the adult in study. Data were collected in 2005 and analyzed in 2008.

Results: Compared to participants who did not purchase from a vending machine, participants who purchased >or=3 days/week were more likely to (1) have unrestricted access to a school vending machine (OR = 1.71; 95% CI = 1.13-2.59); (2) consume regular soda and chocolate candy >or=1 time/day (OR = 3.21; 95% CI = 1.87-5.51 and OR = 2.71; 95% CI = 1.34-5.46, respectively); and (3) purchase pizza or fried foods from a school cafeteria >or=1 day/week (OR = 5.05; 95% CI = 3.10-8.22).

Conclusions: Future studies are needed to establish the contribution that the school-nutrition environment makes on overall youth dietary intake behavior, paying special attention to health disparities between whites and nonwhites.