Quantifying farm-to-fork greenhouse gas emissions for five dietary patterns across Europe and North America: A pooled analysis from 2009 to 2020

Dietary patterns are inherently related to greenhouse (GHG) emissions via agricultural practices and food production systems. As the global population is predicted to increase from 8 billion (current) to 9.6 billion by 2050 added pressure will be placed on existing agricultural systems, resulting in increased GHG emissions thus exacerbating climate change. Therefore, there is an urgent need to understand present-day dietary patterns to shift to sustainable and healthy diets to mitigate GHG emissions and meet future climate targets. However, no review or pooled analyses of dietary pattern emissions from a farm-to-fork perspective has been undertaken to date. The current study sought to i) identify the current dietary habits within high-income regions from 2009 to 2020 and ii) quantify the GHG emissions associated with these dietary patterns via a global systematised review and pooled analysis. Twenty-three peer-reviewed studies were identified through online bibliographic databases. Dietary patterns are being examined based on fixed inclusion/exclusion criteria. Five dietary patterns were identified in the review with their mean GHG emissions: high-protein diets (5.71 CO2eq kg person −1 day −1), omnivorous diet (4.83 CO2eq kg person −1 day −1), lacto-ovo-vegetarian/pescatarian diet (3.86 CO2eq kg person −1 day −1), recommended diet (3.68 CO2eq kg person −1 day −1), and the vegan diet (2.34 CO2eq kg person −1 day −1). The lacto-ovo-vegetarian/pescatarian diet was associated with significantly lower emissions than both the omnivorous and high-protein dietary patterns, with -22% and -41% GHG emissions, respectively. The high-protein dietary pattern exhibited significantly higher GHG emissions than other dietary patterns. Geographically, significant statistical differences (p = 0.001) were only reported for the omnivorous diet between North America and Europe. Findings reveal that GHG emissions vary based on dietary patterns and have the potential to be reduced by shifting dietary patterns, which benefits the environment by lessening one of the drivers of climate change.