title: Sustainable diets for the future: Can we contribute to reducing greenhouse gas emissions by eating a healthy diet?
abstract: 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.
  
  
  METHODS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK. j.macdiarmid@abdn.ac.uk
authors.forename: Jennie I
authors.initials: JI
authors.lastname: Macdiarmid
authors.forename: Janet
authors.initials: J
authors.lastname: Kyle
authors.forename: Graham W
authors.initials: GW
authors.lastname: Horgan
authors.forename: Jennifer
authors.initials: J
authors.lastname: Loe
authors.forename: Claire
authors.initials: C
authors.lastname: Fyfe
authors.forename: Alexandra
authors.initials: A
authors.lastname: Johnstone
authors.forename: Geraldine
authors.initials: G
authors.lastname: McNeill
mesh_terms: D000328:Adult; D000375:Aging; D003365:Costs and Cost Analysis; D016208:Databases, Factual; D004032:Diet / Q000009:adverse effects / Q000191:economics; D018753:Diet, Protein-Restricted / Q000009:adverse effects / Q000191:economics; D005260:Female; D005504:Food Analysis; D005518:Food Preferences; D017752:Greenhouse Effect / Q000517:prevention & control*; D006293:Health Promotion; D006801:Humans; D008875:Middle Aged; D008954:Models, Biological; D009751:Nutritional Requirements; D006113:United Kingdom; D055815:Young Adult