The Healthy Supermarket Coach: effects of a nutrition peer-education intervention in Dutch supermarkets on adolescents' food purchases

Background: Dutch adolescents predominantly purchase unhealthy snacks in supermarkets, which negatively influence their health. The aim of this study was to investigate the short- and longer-term effects of a nutrition peer-education intervention in supermarkets on food purchases and determinants of food purchase behaviour among adolescents of different education levels.

Methods: We performed a quasi-experimental study in three supermarkets (two intervention and one comparison school) in Amsterdam, the Netherlands. The intervention schools received a 45-min peer-education workshop in the supermarket near their school, and the comparison school received no intervention. The workshops also included a 2-week 'healthy snacking challenge' and were led by two young supermarket employees. Measurements were performed 2 weeks before the intervention (T0) 2 weeks after (T1) and 3 months (T2) after the intervention. Cash receipts were used to examine food purchases (n = 458) and questionnaires to examine determinants of food purchase behaviour (n = 463).

Results: The nutrition peer-education intervention did not improve food purchases but did improve several determinants of food purchase behaviour. Adolescents from the intervention schools reported improved nutritional knowledge (β = 0.38, 95% CI: 0.04-0.72) at T1, more favourable attitudes (β = 0.21, 95% CI: 0.00-0.42) and stronger social support (β = 0.27, 95% CI: 0.02-0.53) for healthy food purchases at T2 compared to those from the comparison schools. Adolescents with a low level of education reported more short- and longer-term improvements of determinants of food purchase behaviour compared to those with a higher level of education.

Conclusions: While nutrition peer education in supermarkets did not improve adolescents' food purchases in the supermarket, determinants of food purchase behaviour did improve. The intervention was especially effective among adolescents with a low level of education. Nevertheless, to promote healthy food purchases of adolescents in supermarkets, more efforts are needed.