Implementation and impact of the ban on the sale of ultra-processed foods to minors in Mexico

Childhood obesity continues to be a public health issue globally therefore, it is necessary to test and evaluate new prevention policies and interventions. This study will evaluate both the implementation and impact of a new and unprecedented law that bans the sale of ultra-processed foods to minors in the state of Oaxaca, Mexico. In a first stage we will survey and conduct interviews with implementation actors including ministry of health officials, municipal authorities and school directors. We will measure implementation outcomes, specifically whether the policy is acceptable to actors, perceived feasible to implement and relevant. Simultaneously, we will conduct a mystery client study where children and adolescents will attempt to purchase a banned product from selected community retailers and school canteens. With this study component we will be able to objectively measure adoption of the policy and whether it is being implemented with fidelity. If we find that over 20% of food retailers and schools have adopted the law (i.e. they do not sell ultra-processed foods to minors), then the study will progress to stage 2 where we will measure the impact of the law on children's diet and obesity prevalence. To do this, we will leverage data from from six waves of Mexico's National Health and Nutrition Surveys to estimate ultra-processed food consumption and obesity prevalence before and after the law came into effect (2020). This will be done for Oaxaca and comparison states where a similar policy has not been approved. The results of this study will show whether the policy is effective, whether it can be successfully implemented and potentially rolled-out to other geographies.

On August 2020 the state of Oaxaca in the south of Mexico approved a new law that bans the sale, distribution and donation of packaged ultra-processed foods (UPFs) and beverages to minors. This is an unprecedented obesity prevention policy which equates UPFs to other harmful products such as alcohol and tobacco. This proposal aims to evaluate the implementation and impact of this age-of-sale law. This is a milestoned proposal organized in two stages. In stage 1 we will use Proctor's Implementation Outcomes Framework and associated Constructs from the Consolidated Framework for Implementation Research (CFIR) to investigate implementation outcomes (acceptability, appropriateness, feasibility, cost, adoption and fidelity) and their determinants. We will conduct surveys and semi-structured interviews with implementation actors and will complement this information with a mystery client study; where children and adolescents will attempt to purchase banned products in stores and schools. The project will progress onto stage 2 if the mystery client study finds that at least 20% of schools and food outlets have implemented the law. In the second stage we aim to evaluate the impact of the law on dietary outcomes, specifically dietary energy contribution from UPFs, processed foods and unprocessed foods, and overweight and obesity prevalence. We will leverage data from six waves of Mexico's National Health and Nutrition Surveys to estimate pre and post intervention estimates for the outcomes of interest for Oaxaca and comparison states. The analyses will use difference-in-difference fixed effects models to estimate impact. The results of this study will be used as rigorous evidence to justify roll-out in other geographies if the policy is found to be effective. If effectiveness is found to be limited or null, our study will help to understand why, to make changes if possible, or to abandon this strategy in favor of other approaches.