BACKGROUND: Diet plays a vital role in human health and environmental effects. Monitoring diet quality and its relationship to both health and environment are essential for policy making.
OBJECTIVES: This study aimed to analyze trends in the Planetary Health Diet Index (PHDI) and its associations with daily greenhouse gas (GHG) emissions from food, disease-related biomarkers, anthropometric measurements, obesity, and all-cause mortality in the United States population.
METHODS: We analyzed 27,181 adults in the National Health and Nutrition Examination Survey (NHANES) from 2005 to 2018, except for the mortality analysis. 23,599 adults were analyzed as the 2017-2018 NHANES dietary data were removed due to the potential for reverse causation. We calculated PHDI scores by using 2 24-h dietary recalls and GHG by linking the consumption of individual foods to dataFRIENDS, a food-environmental impact database. To assess associations with the PHDI, we used generalized linear regression models for GHG, disease-related biomarkers, and obesity and used the Cox proportional hazards model for all-cause mortality.
RESULTS: The energy-adjusted mean of the PHDI (140 possible points) increased from 68.6 in 2005-2006 to 71.7 in 2017-2018 (P-trend < 0.001). Compared with the lowest quintile (Q1), the highest PHDI quintile (Q5) was associated with 25% lower GHG emissions, a better cardiometabolic profile, lower prevalence ratios of obesity [0.59; 95% confidence interval (CI): 0.50, 0.69] and abdominal obesity (0.74; 95% CI: 0.66, 0.82), and a lower risk of all-cause death [hazard ratio (HR): 0.65; 95% CI: 0.54, 0.78].
CONCLUSIONS: These results underscore the potential health and GHG emission benefits aligned with the planetary health diet.
