title: Diet-related greenhouse gas emissions assessed by a food frequency questionnaire and validated using 7-day weighed food records.
abstract: BACKGROUND
  The current food system generates about 25 % of total greenhouse gas emissions (GHGE), including deforestation, and thereby substantially contributes to the warming of the earth's surface. To understand the association between food and nutrient intake and GHGE, we therefore need valid methods to assess diet-related GHGE in observational studies.
  
  
  METHODS
  Life cycle assessment (LCA) studies assess the environmental impact of different food items. We linked LCA data expressed as kg carbon dioxide equivalents (CO2e) per kg food product to data on food intake assessed by the food frequency questionnaire (FFQ) Meal-Q and validated it against a 7-day weighed food record (WFR). 166 male and female volunteers aged 20-63 years completed Meal-Q and the WFR, and their food intake was linked to LCA data.
  
  
  RESULTS
  The mean GHGE assessed with Meal-Q was 3.76 kg CO2e per day and person, whereas it was 5.04 kg CO2e using the WFR. The energy-adjusted and deattenuated Pearson and Spearman correlation coefficients were 0.68 and 0.70, respectively. Moreover, compared to the WFR, Meal-Q provided a good ranking ability, with 90 % of the participants classified into the same or adjacent quartile according to their daily average CO2e. The Bland-Altman plot showed an acceptable level of agreement between the two methods and the reproducibility of Meal-Q was high.
  
  
  CONCLUSIONS
  This is the first study validating the assessment of diet-related GHGE by a questionnaire. The results suggest that Meal-Q is a useful tool for studying the link between food habits and CO2e in future epidemiological studies.
authors: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, SE-171 77, Stockholm, Sweden. Camilla.Sjors@ki.se.
authors: Camilla
authors: C
authors: Sjörs
authors: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, SE-171 77, Stockholm, Sweden. Sara.Raposo@ki.se.|Current address: Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA. Sara.Raposo@ki.se.
authors: Sara E
authors: SE
authors: Raposo
authors: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, SE-171 77, Stockholm, Sweden. Arvid.Sjolander@ki.se.
authors: Arvid
authors: A
authors: Sjölander
authors: KTH - Royal Institute of Technology, School of Computer Science and Communication, SE-100 44, Stockholm, Sweden. ob1@kth.se.|Stanford Graduate School of Education, Stanford, CA, USA. ob1@kth.se.
authors: Olle
authors: O
authors: Bälter
authors: Department of Energy and Environment, Chalmers University of Technology, SE-412 96, Gothenburg, Sweden. Hedenus@chalmers.se.
authors: Fredrik
authors: F
authors: Hedenus
authors: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, SE-171 77, Stockholm, Sweden. Katarina.Balter@ki.se.|Stanford Prevention Research Center, Stanford School of Medicine, Stanford, USA. Katarina.Balter@ki.se.
authors: Katarina
authors: K
authors: Bälter
mesh_terms: D000328:Adult; D002245:Carbon Dioxide / Q000032:analysis*; D004034:Diet Surveys / Q000706:statistics & numerical data; D004040:Dietary Carbohydrates / Q000032:analysis; D004041:Dietary Fats / Q000032:analysis; D004044:Dietary Proteins / Q000032:analysis; D005247:Feeding Behavior; D005260:Female; D005518:Food Preferences; D017752:Greenhouse Effect / Q000517:prevention & control* / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008875:Middle Aged; D064167:Recommended Dietary Allowances; D011795:Surveys and Questionnaires; D055815:Young Adult
chemical_list: D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004044:Dietary Proteins; D002245:Carbon Dioxide