Cut environmental impacts

A 2017 meta-analysis of life cycle assessments from 742 agricultural systems and over 90 different foods looked at the impact of these foods across five environmental indicators: greenhouse gas emissions, land use, energy use, acidification potential (a measure of nutrient loading), and eutrophication potential (a measure of nutrient run-off).  

Across all indicators, it was found that ruminant meat had environmental impacts 20-100 times higher those of plants; and eggs, dairy, pork, poultry, and seafood had impacts 2-25 times higher than plants per kilocalorie of food produced. 

Additionally, some common misconceptions were dispelled by the study including the finding that grass-fed beef has higher land-use requirements and generates more greenhouse gas emissions than grain-fed beef.  This is because grass-fed animals require higher feed inputs due to the lower nutrient density and digestibility of grass versus grain.  Grass-fed animals also take longer to reach their market weight and so lifetime methane emissions per unit of food are higher.A 2018 meta-analysis by Oxford University that derived data from 38,700 commercially viable farms in 119 countries had similar findings on the comparative environmental impact of various food groups.  The study concluded that the shift from current diets to diets that exclude animal products would reduce global food land use by 76% and food’s greenhouse gas emissions by an average of 49%.  In countries where meat consumption is high compared to the global average, the reduction in greenhouse gas emissions from the shift to plant-based diets would be as high as 73%.  The authors found that even the impacts of the lowest-impact animal products still exceeded those of vegetable substitutes.