(OR03-01-24) Planetary Health Diet Index Trends and Associations With Dietary Greenhouse Gas Emissions, Disease Biomarkers, Obesity, and Mortality in the United States (2005-2018)

Objectives: This study aims to analyze trends in the Planetary Health Diet Index (PHDI), a dietary index developed to assess adherence to the EAT-Lancet diet proposed by the EAT-Lancet Commission, and to assess its associations with daily greenhouse gas emissions from food (GHG), disease-related biomarkers, anthropometric measurements, obesity, and all-cause mortality in the U.S. population.

Methods: We analyzed 32,899 adults in the National Health and Nutrition Examination Survey (NHANES) from 2005 to 2018. We calculated PHDI scores from two 24-hour dietary recalls and estimated GHG by linking consumption of individual foods to dataFRIENDS, a food-environmental impact database. Linear trend analyses for PHDI, adjusted for energy intake, age group, sex, race/ethnicity, family income to poverty ratio, household size, and education, were conducted. With additional adjustments for marital status, smoking, alcohol intake, physical activity, dietary supplement use, and body mass index (BMI) category, we used generalized linear regression models to assess associations between PHDI and GHG, disease-related biomarkers, anthropometric measurements, and obesity. Lastly, we used Cox proportional hazards model to estimate the association between PHDI and all-cause mortality followed up through December 31, 2019.

Results: The raw mean of PHDI increased from 67.4 in 2005-2006 to 72.1 in 2017-2018. The increasing trend was significant after adjusting for covariates in overall and all covariate-stratified populations (from 69.9 to 71.1, p < 0.001). When compared to the lowest PHDI quintile (Q1), the highest PHDI quintile (Q5) was associated with lower GHG (-1.1 kg CO2/day, p < 0.001) , a better cardiometabolic profile (e.g., higher high-density lipoprotein (+3.2 mg/dL, p < 0.001), lower triglyceride (-26 mg/dL, p = 0.002), lower BMI (-2.1 kg/m2, p < 0.001), lower waist circumference (-5.6 cm, p < 0.001)), and lower prevalence ratios of obesity (0.61, 95%CI: 0.52-0.71) and abdominal obesity (0.75, 95%CI: 0.68-0.84). For all-cause mortality, PHDI was significantly associated with lower risk of death in the overall population, females (HR:0.41, 95%CI: 0.25-0.69), but not for males (HR: 1.09, 95% CI: 0.67-1.77).

Conclusions: These results underscore the potential health and climate benefits of sustainable dietary patterns aligned with the PHDI.

Funding Sources: N/A