Changes in Children’s Adherence to Sustainable Healthy Diets During the Implementation of Chile’s Food Labelling and Advertising Law: A Longitudinal Study (2016–2019)

Objectives: This longitudinal study measured changes in adherence to sustainable healthy diets in 698 Chilean children (aged 3–6 years at baseline) over the period that Chile’s Food Labelling and Advertising Law was implemented. Methods: Dietary data were collected annually from 2016 to 2019 applying single multiple-pass 24 h dietary recalls to children’s primary caretakers. The Planetary Health Diet Index for Children and Adolescents (PHDI-C) was used to quantify adherence to sustainable healthy diets where higher scores indicate better adherence. Linear mixed models were fitted to estimate the change in PHDI-C total and individual component scores from 2016 to 2019. Results: Mean total PHDI-C score decreased from 50.1 points in 2016 to 46.3 and 46.1 in 2018 and 2019, respectively (p-value < 0.001), suggesting that children’s overall adherence to sustainable healthy diets was low and decreased over time. Intake of legumes, fruits, dark green vegetables, red and orange vegetables, and vegetable oils decreased, while intake of palm oil, red meats, and animal fats increased, resulting in small but significant declines in eight PHDI-C component scores. Whole cereal intake increased, while the consumption of dairy products and added sugars decreased, resulting in improvements in three PHDI-C component scores. Conclusions: Aside from the decrease in added sugar intake, all dietary changes observed in this study were consistent with trends described among children transitioning from pre-school age to school age. The Law might have contributed to reducing children’s added sugar intake, but further research is required to establish causality.