Assessment of Diet Quality and Associated Environmental Impacts in Ireland

Abstract

Abstract Background Suboptimal diets continue to be a major contributor to the global burden of disease, while food production contributes to climate change and environmental degradation. Food systems account for >30% of anthropogenic global greenhouse gas emissions (GHGE), and around 70% of freshwater use. Research on healthier diets having lower environmental impacts has been inconsistent. This study aimed to explore the association between environmental footprints and diet quality among older Irish adults. Methods The Mitchelstown Cohort was a cross-sectional study conducted between 2010 and 2011 in County Cork, Ireland. Dietary data was available for 1,862 participants. Adherence to three a priori defined diet quality metrics (Dietary Approaches to Stop Hypertension (DASH), Mediterranean diet (MD), and the Healthy Eating Index 2015 (HEI-2015)) were measured. Those in quartile four (Q4) of each metric were the most adherent to the respective dietary recommendations. Environmental impact of foods was quantified by linking food items to GHGE and blue water (BW) use impact factors, based on life cycle assessment (LCA) literature. Results The median daily diet in Ireland was associated with 6.8 kg CO2-equivalents per day and 425.1 litres of blue water. Males had significantly higher dietary GHGE but a lower water footprint compared to females (P < 0.001). Higher diet quality was inversely associated with GHGE according to the DASH and MD diet (adjusted for age, sex, and energy intake). Adherence to the DASH and MD diet was positively associated with BW use. No association between the HEI and GHGE and BW use was found in the adjusted model. Conclusions Irish dietary patterns are unhealthy and unsustainable. Higher quality diets reduced GHGE but increased water use. Future research must focus on identifying culturally-acceptable, optimised dietary patterns, where health and impact indicators align to curtail environmental burdens potentially transferring. Key messages • The healthiness of a diet is dependent in part on the constructs and scoring criteria of the diet quality metric used. The metrics have conceptual differences which may explain heterogeneous findings. • The sustainability of diets is dependent on the environmental indicator(s) assessed. Future dietary patterns must be healthy, culturally-acceptable, equitable, and align across multiple indicators.