Peru’s front-of-package warning label policy and changes in the healthfulness of the food supply: a pre-post observational study

Introduction In 2019, Peru implemented the first phase of a front-of-package warning label (FOPWL) policy requiring packaged foods and beverages exceeding thresholds for total sugars, sodium, saturated fats or containing trans fats to display warning labels. While intended to inform consumers, such policies may also incentivise product reformulation. This study assessed differences in the proportion and nutrient content of regulated (‘high in’) products in the Peruvian food supply after FOPWL policy implementation.Methods Product-level nutritional information was collected from packaged foods and beverages during two periods: pre-implementation (T0: March–June 2019; n=2481) and post implementation (T1: March 2020–February 2021; n=3018). The proportion of products exceeding thresholds for nutrients of concern (sugars, sodium and saturated fats) and shifts in nutrient distributions across quartiles were compared pre-implementation and post implementation of the law in repeated cross-sectional samples and a longitudinal subsample (products collected in both periods, n=1694). Generalized estimating equations and logistic regression assessed differences in the proportion of ‘high in’ products, while quantile regression evaluated shifts in nutrient distributions.Results In cross-sectional analyses over T1-T0 period, the proportion of ‘high in’ products declined by 6 percentage points (61% to 55%) among foods and by 11 percentage points (31% to 19%) among beverages. Relative reductions were observed in products ‘high in’ sugars (10% among foods; 37% among beverages), sodium (16% among foods) and saturated fats (7% among foods). Reductions varied across product categories and were greatest in those where thresholds were set below the prepolicy 75th percentile of baseline nutrient distributions. Longitudinal results were largely consistent with cross-sectional findings.Conclusion Peru’s first FOPWL policy phase was associated with reductions in the proportion of products ‘high in’ nutrients of concern, suggesting reformulation occurred across diverse product categories. These findings highlight the potential of mandatory FOPWL policies to improve the nutritional quality of the food supply and support efforts to reduce diet-related diseases.