Adherence to the EAT-Lancet Healthy Reference Diet in relation to Coronary Heart Disease, All-Cause Mortality Risk and Environmental Impact: Results from the EPIC-NL Cohort

Objectives To construct a diet-score measuring the level of adherence to the Healthy Reference Diet (HRD), to explore whether adherence to the HRD is associated with coronary heart disease (CHD), all-cause mortality risk, and to calculate its environmental impact. Design Prospective cohort study. Setting The Dutch contribution to the European Prospective Investigation into Cancer and Nutrition (EPIC-NL). Participants 37,349 adults (20-70y) without CHD at baseline. Main outcome measures Primary outcomes were incident CHD and all-cause mortality. Secondary outcomes were greenhouse gas emission (GHGE), land use, blue water use, freshwater eutrophication, marine eutrophication, and terrestrial acidification. Results During a median 15.3-year follow-up, 2,543 cases of CHD occurred, and 5,648 individuals died from all causes. The average HRD-score was 73 (SD=10). High adherence to the HRD was associated with a 15% lower risk of CHD (hazard ratio 0.85, 95% confidence interval 0.75 to 0.96), as well as a 17% lower risk of all-cause mortality (hazard ratio 0.83, 95% confidence interval 0.77 to 0.90) in multivariable-adjusted models. Better adherence to the HRD was associated with lower environmental impact from GHGE (β= -0.10 kg CO2-eq, 95% confidence interval -0.13 to -0.07), land use (β= -0.11 m 2 per year, 95% confidence interval -0.12 to -0.09), freshwater eutrophication (β= -0.000002 kg P-eq, 95% confidence interval -0.000004 to -0.000001), marine eutrophication (β= -0.00035 kg N-eq, 95% confidence interval -0.00042 to -0.00029), and terrestrial acidification (β = -0.004 kg SO2-eq, 95% confidence interval -0.004 to -0.003), but with higher environmental impact from blue water use (β=0.044 m 3 , 95% confidence interval 0.043 to 0.045). Conclusion High adherence to the HRD was associated with lower risk of CHD and all-cause mortality. Additionally, increasing adherence to the HRD could lower some aspects of the environmental impact of diets, but attention is needed for the associated increase in blue water use.