Sustainable diets for the future: can we contribute to reducing greenhouse gas emissions by eating a healthy diet?123

• Published in: The American journal of clinical nutrition 2012-09, Vol.96 (3), p.632-639
• Main Authors: Macdiarmid, Jennie I, Kyle, Janet, Horgan, Graham W, Loe, Jennifer, Fyfe, Claire, Johnstone, Alexandra, McNeill, Geraldine
• Format: Article
• Language: English
• ISSN: 0002-9165; 1938-3207
• DOI: 10.3945/ajcn.112.038729

Background: Food systems account for 18–20% of UK annual greenhouse gas emissions (GHGEs). Recommendations for improving food choices to reduce GHGEs must be balanced against dietary requirements for health. Objective: We assessed whether a reduction in GHGEs can be achieved while meeting dietary requirements for health. Design: A database was created that linked nutrient composition and GHGE data for 82 food groups. Linear programming was used iteratively to produce a diet that met the dietary requirements of an adult woman (19–50 y old) while minimizing GHGEs. Acceptability constraints were added to the model to include foods commonly consumed in the United Kingdom in sensible quantities. A sample menu was created to ensure that the quantities and types of food generated from the model could be combined into a realistic 7-d diet. Reductions in GHGEs of the diets were set against 1990 emission values. Results: The first model, without any acceptability constraints, produced a 90% reduction in GHGEs but included only 7 food items, all in unrealistic quantities. The addition of acceptability constraints gave a more realistic diet with 52 foods but reduced GHGEs by a lesser amount of 36%. This diet included meat products but in smaller amounts than in the current diet. The retail cost of the diet was comparable to the average UK expenditure on food. Conclusion: A sustainable diet that meets dietary requirements for health with lower GHGEs can be achieved without eliminating meat or dairy products or increasing the cost to the consumer.