The ultra-processed food content of school meals and packed lunches in the UK, 2008-17: a pooled cross-sectional study

Abstract

Background: British children have the highest ultra-processed food (UPF) intake in Europe, concerning as UPF is linked to adverse health outcomes. Schools are a potential setting for intervention, yet the rate of UPFs consumed at schools is currently unknown. This study aimed to describe the UPF content of school food in the UK and to explore differences in UPF content by meal type (school meals and packed lunches [food from home]) and children's household income.

Methods: We performed a pooled cross-sectional analysis of 1895 primary school children (aged 4-11 years) and 1408 secondary school children (aged 11-18 years) using data from the UK's National Diet and Nutrition Survey (from Feb, 2008, to June, 2017). Student's meal type was recorded using food diaries. UPF intake was defined using the NOVA food classification system. Income was measured through interview. We used quantile regression models to assess the association between meal type and lunchtime UPF intake (by both the percentage of calories and weight). We stratified models by school phase (primary or secondary) and interacted meal type with income.

Findings: The majority of schoolchildren's lunch was defined as UPFs, with secondary school children having higher median intakes of UPFs than primary school children (78% kcal [IQR 58-95] vs 73% kcal [55-86). School meals were associated with a lower median UPF intake than packed lunches for primary school children (61% kcal [IQR 44-75] vs 81% kcal [71-91]) and for secondary school children (70% kcal [IQR 48-89] vs 84% kcal [65-99]). Results were similar when UPFs were analysed as a percentage of the total weight of lunch. Overall, income was inversely associated with UPF lunch content. However, in primary school children, there was no significant association between percentage of UPF content of school meals by weight.

Interpretation: In the first nationally representative study, we showed that UK school children have a high intake of UPFs at lunch. UPF intake was increased in children who consumed packed lunches, secondary school children, and children of a lower income. School meal procurement policies must be re-evaluated to protect children from high UPF intake.

Funding: This study was funded by the National Institute for Health Research School for Public Health Research.