Greenhouse gas emissions, cost, and diet quality of specific diet patterns in the United States

Abstract

Background: Major policy agendas are calling for accelerated investment in research that addresses the impact of diet patterns on multiple domains of sustainability.

Objectives: To evaluate the comparative greenhouse gas emissions, diet cost, and diet quality of plant-based, low-grain, restricted carbohydrate, low-fat, and time-restricted diet patterns on a daily per capita basis.

Methods: Dietary data from the National Health and Nutrition Examination Survey (2013-2016, n = 4025) were merged with data on greenhouse gas emissions (GHGEs) and food prices from multiple databases. The Healthy Eating Index-2015 was used to measure diet quality.

Results: The plant-based diet pattern had the lowest GHGEs [3.5 kg carbon dioxide equivalent (CO₂eq); 95% confidence interval (CI): 3.3, 3.8 kg CO₂eq] and among the lowest diet cost ($11.51; 95% CI: $10.67, $12.41), but diet quality (45.8; 95% CI: 43.3, 48.5) was similar (P > 0.005) to most other diet patterns. All of the sustainability impacts of the low-grain diet pattern were intermediate. The restricted carbohydrate diet pattern had the highest diet cost ($18.46; 95% CI: $17.80, $19.13) but intermediate diet quality (46.8; 95% CI: 45.7, 47.9) and moderate-to-high GHGEs (5.7 kg CO₂eq; 95% CI: 5.4, 5.9 kg CO₂eq). The low-fat diet pattern had the highest diet quality (52.0; 95% CI: 50.8, 53.1) and intermediate GHGEs (4.4 kg CO₂eq; 95% CI: 4.1, 4.6 kg CO₂eq) and diet cost ($14.53; 95% CI: $13.73, $15.38). The time-restricted diet pattern had among the lowest diet quality score (42.6; 95% CI: 40.8, 44.6), had GHGEs similar to most other diet patterns (4.6 kg CO₂eq; 95% CI: 4.2, 5.0 kg CO₂eq), and low-to-moderate diet cost ($12.34; 95% CI: $11.38, $13.40).

Conclusions: Most diet patterns are associated with sustainability trade-offs. The nature of these trade-offs can help inform discussions on food and nutrition policy in the United States, including the National Strategy on Hunger, Nutrition, and Health, and future Dietary Guidelines for Americans.

Keywords: Healthy Eating Index-2015; diet cost; diet quality; greenhouse gas emissions; low carbohydrate; plant-based; sustainability.