Greater adherence to the Dietary Guidelines for Americans is associated with lower diet-related greenhouse gas emissions but higher costs

Abstract

IntroductionFew studies have evaluated the sustainability of popular diet patterns in the US, which limits policy action and impedes consumer efficacy to make sustainable dietary changes. This study filled this gap by evaluating the relationship between diet quality, greenhouse gas emissions (GHGE), and diet cost for plant-based, restricted carbohydrate, low grain, low fat, and time restricted diet patterns.MethodsDietary data were retrieved from the National Health and Nutrition Examination Survey (2011–2018, n = 8,146) and linked with data on GHGE and food prices from publicly available databases. Diet quality was measured using the Healthy Eating Index-2015. The present study (1) compared the mean diet quality, GHGE, and diet cost between diet patterns, (2) evaluated the association of diet quality to GHGE and diet cost for each diet pattern, and (3) estimated the contribution of food sources to GHGE and diet cost for each diet pattern.ResultsHigher diet quality was associated with lower GHGE for the general population and for most diet patterns (p < 0.01) except for the plant-based and time restricted diet patterns (p > 0.05). Higher diet quality was associated with higher cost for the general population and for all dietary patterns (p < 0.01) except the time restricted diet pattern (p > 0.05). Protein foods, mostly beef, accounted for the largest share of GHGE (29–40%) and diet cost (28–47%) for all diet patterns except plant-based.DiscussionHigher diet quality was associated with lower GHGE but was often accompanied by higher diet cost. These sustainability trade-offs can help inform major policy discussions in the US and shed light on further research needs in the area of food systems transformation.

Dietary quality and dietary greenhouse gas emissions in the USA: a comparison of the planetary health diet index, healthy eating index-2015, and dietary approaches to stop hypertension

“…We found that, in this nationally-representative survey of adults living in the US, improved dietary quality across the three dietary indices we examined was associated with lower GHGE. The inverse relationship between dietary quality and lower diet-related GHGE is consistent with several recent studies published in the US [ 12 , 17 ]. Another NHANES study found that vegan, vegetarian, and pescetarian diets had higher dietary quality and lower diet-related GHGE than omnivorous, keto, or paleo diets [ 13 ].…”

“…Previous research in the US has consistently found that healthy plant-based diets are associated with lower diet-related GHGE, while unhealthy plant-based diets do not necessarily have the same environmental benefits [ 12 – 14 ]. In this context, the PHDI can fill an important gap, as it is a novel a priori measure that considers both environmental sustainability and health outcomes.…”

Augmenting the National Nutrition Data System to Promote Diet Sustainability Analyses

“…The FCID has been linked to several types of computational models that have been used to evaluate the environmental impacts of dietary intake. The FCID has been linked to data from life cycle analysis (LCA) [ 13 , 32 , 75 , 86 ] to evaluate the association between dietary intake and greenhouse gas emissions [ 13 , 19 , 21 , [31] , [32] , [33] , 75 , [86] , [87] , [88] , [89] , [90] , [91] ], energy use [ 13 ], water use and scarcity [ 32 , 86 , 90 , 91 ], and land use [ 86 , 90 , 91 ]. Greenhouse gas emissions have also been evaluated using carbon accounting methods [ 92 ].…”

“…Given its versatility, prior studies have used the FCID to evaluate the environmental impacts of individual foods or food groups [ 13 , 20 , 21 , 30 , 32 , 86 , 88 , 90 , 91 ] as well as diet patterns, including actual [ 19 , 31 , 88 ] and modeled [ 87 ] diet patterns. These also include diet patterns differentiated by diet quality [ 19 , 20 , 30 , 31 , 33 , 88 ] or other characteristics such as meat intake [ 87 ], as well as counterfactual scenarios such as adherence to dietary recommendations [ 90 , 93 ] or food substitutions [ 33 ]. Others have used the FCID to evaluate the environmental impacts of food loss and waste [ 13 , [19] , [20] , [21] , 30 , 87 , 88 ] as well as the impacts associated with demographic and behavioral characteristics [ 21 , 86 , [89] , [90] , [91] , [92] ].…”

“…These also include diet patterns differentiated by diet quality [ 19 , 20 , 30 , 31 , 33 , 88 ] or other characteristics such as meat intake [ 87 ], as well as counterfactual scenarios such as adherence to dietary recommendations [ 90 , 93 ] or food substitutions [ 33 ]. Others have used the FCID to evaluate the environmental impacts of food loss and waste [ 13 , [19] , [20] , [21] , 30 , 87 , 88 ] as well as the impacts associated with demographic and behavioral characteristics [ 21 , 86 , [89] , [90] , [91] , [92] ].…”