Integrating health and greenhouse gas emission metrics to promote a sustainable food system
File(s)
Author(s)
Gaines, Allison
Type
Thesis
Abstract
Background
Uptake of healthy and sustainable diets is required to reduce the non-communicable disease burden and protect our planet. This thesis sought to calculate product-specific greenhouse gas emission (GHGe) estimates for products available in Australian supermarkets in 2019. It assessed the association between GHGe estimates and nutrient profiles and the potential reductions in total GHGe achieved by switching purchases to lower-GHGe products.
Methods
The GHGe values for each ingredient in each product were weighted and summed to determine a GHGe estimate for each product, with further adjustments to account for level of processing and transport. The significance of trends between GHGe estimates and the four nutrient profiling scores were assessed. Product switches were evaluated based on GHGe percentiles to test the impact of progressively switching towards lower GHGe products.
Results
23,550 products were included in these analyses. The median product-specific GHGe estimate (95% UI) for all products was 2.24 (1.22-4.20) kg CO2eq/kg product (range [0.0002, 73.5]; interquartile range (IQR) [1.03 (0.81-1.64), 6.94 (5.13-18.5)]. ‘Meat and meat products’ and ‘Confectionery’ had a disproportionately higher median GHGe contributions when compared to all other categories. Products with better nutrient profiles were more likely to have lower median GHGe estimates than products with worse nutrient profiles (all p-values<0.001). Switching higher-emission products for lower-emission products had the potential to reduce total emissions by over 70%.
Conclusion
Standardised metrics to communicate the GHGe of supermarket products alongside nutrient profiling metrics can help to make great strides in minimising adverse health and environmental impacts. A substantial reduction in the GHGe attributable to supermarket products could be achieved by directing manufacturing and marketing towards healthier and lower GHGe impact products. Dual health and GHGe impacts of specific products should be used to define food policy and industry regulation.
Uptake of healthy and sustainable diets is required to reduce the non-communicable disease burden and protect our planet. This thesis sought to calculate product-specific greenhouse gas emission (GHGe) estimates for products available in Australian supermarkets in 2019. It assessed the association between GHGe estimates and nutrient profiles and the potential reductions in total GHGe achieved by switching purchases to lower-GHGe products.
Methods
The GHGe values for each ingredient in each product were weighted and summed to determine a GHGe estimate for each product, with further adjustments to account for level of processing and transport. The significance of trends between GHGe estimates and the four nutrient profiling scores were assessed. Product switches were evaluated based on GHGe percentiles to test the impact of progressively switching towards lower GHGe products.
Results
23,550 products were included in these analyses. The median product-specific GHGe estimate (95% UI) for all products was 2.24 (1.22-4.20) kg CO2eq/kg product (range [0.0002, 73.5]; interquartile range (IQR) [1.03 (0.81-1.64), 6.94 (5.13-18.5)]. ‘Meat and meat products’ and ‘Confectionery’ had a disproportionately higher median GHGe contributions when compared to all other categories. Products with better nutrient profiles were more likely to have lower median GHGe estimates than products with worse nutrient profiles (all p-values<0.001). Switching higher-emission products for lower-emission products had the potential to reduce total emissions by over 70%.
Conclusion
Standardised metrics to communicate the GHGe of supermarket products alongside nutrient profiling metrics can help to make great strides in minimising adverse health and environmental impacts. A substantial reduction in the GHGe attributable to supermarket products could be achieved by directing manufacturing and marketing towards healthier and lower GHGe impact products. Dual health and GHGe impacts of specific products should be used to define food policy and industry regulation.
Version
Open Access
Date Issued
2023-10-05
Date Awarded
01/03/2024
Copyright Statement
Creative Commons Attribution NonCommercial Licence
License URL
Advisor
Neal, Bruce
Seferidi, Paraskevi
Elliott, Paul
Sponsor
Imperial College London
Publisher Department
School of Public Health
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)