Trends in self-reported responses to nutrition facts labels before and after nutrition labeling policy implementation: A comparison of adults in the United States and Mexico

Abstract Background In 2020-2021, both Mexico and the US implemented similar, newly formatted nutrition facts labels (NFLs). Mexico simultaneously implemented front-of-package warning labels that emphasize high levels of less healthy nutrients described in NFLs (e.g., calories, sugar, salt, trans fat, saturated fat) to enhance consumer understanding of nutrition information. Objective To evaluate these policies by comparing pre- and post-policy trends in self-reported responses to NFLs. Methods Annual surveys from the adult International Food Policy Study (2018-2023) were analyzed for Mexico (n=24,832) and the US (n=25,464). Outcomes included reported ease of finding nutrition information in grocery stores and awareness, use, and understanding of NFLs (all=1-5 Likert scales). A difference-in-differences method using adjusted and weighted linear regression models compared cross-country differences in trends for these outcomes over the transition (2019-2020), early (2019-2021), mid (2019-2022) and late (2019-2023) post-implementation periods relative to pre-policy trends (2018-2019). Results Trends over the transition period (vs. pre-policy) were stable within and across countries. For all outcomes, trends up to the early implementation period (vs. pre-policy) were more positive in Mexico than the US (i.e., ease of finding nutrition information B=0.195, p=0.003; awareness B=0.220, p<0.001; understanding B=0.332, p<0.001; use B=0.211, p=0.006), driven by both increases in Mexico (i.e., ease of finding B=0.126, p=0.008; awareness B=0.132, p=0.001; understanding B=0.198, p<0.001; use B=0.087, p=n.s.) and decreases in the US (i.e., ease of finding information B=n.s.; awareness B=-0.088, p=-0.049; understanding B=-0.134, p=0.002; use B=-0.124, p=0.025). When evaluating mid and late post-implementation periods, contrasts favored Mexico over the US for all outcomes except NFL use, which did not differ within or across countries. Conclusion Newly formatted NFLs in the US did not increase awareness, understanding, or use of NFLs, particularly when compared to Mexico's new NFLs that were accompanied by front-of-package warning labels. Further research should determine labeling effects on eating behaviors.