Evaluation of environmental performance of dietary patterns in the United States considering food nutrition and satiety

Food production substantially depletes the environment in different ways, but little is known about how overall dietary patterns relate to these environmental impacts. The objective of this study was to evaluate the environmental performance of different dietary patterns among U.S. adults using life cycle assessment (LCA). A "typical" dietary pattern was compared with those recommended by the Dietary Guidelines for Americans, including "healthy U.S.", Mediterranean and lacto-ovo vegetarian. Supplemental functional units (FUs) were applied to incorporate the functions of food to provide nutrition and satiety, namely Nutrient Rich Foods Index 9.3 (NRF9.3), Nutritional Quality Index (NQI), and Fullness Factor™ (FF). Life cycle inventory data was collected for 14 food categories consisting of 76 component foods, and their midpoint environmental impacts were calculated, with particular focus on global warming potential. Diets in accordance with different patterns were constructed from selected component foods at a reference energy amount of 2000 kcal. Vegetarian diets on average generated the lowest carbon footprint regardless of the FU. However, large possible variations in the environmental profiles of the compared diets were identified due to the wide range of food choices within a pattern, which showed highly different nutrition and satiety scores even within the same food category. Animal products, including meat and dairy especially, and discretionary foods were identified as the specific food categories that contributed the most to the global warming potential. Discretionary foods consistently exhibited higher impacts on the basis of nutritional FUs due to their low nutrient density. The results can be implied as practical guidelines to help reduce the carbon footprint associated with current U.S. diets without compromising their nutritional adequacy and satiety.