Published today in Nature Food, the study assessed the environmental impacts of various dietary choices, including high and low meat, pescetarian, vegetarian, and vegan diets, and provides valuable insights into the relationship between our food choices and the health of the planet.
The research team, led by Professor Peter Scarborough from the Nuffield Department of Primary Care Health Sciences, analysed data from over 55,000 individuals, linking their dietary preferences with information on the environmental impacts of the foods they consumed.
The results were striking, demonstrating that vegans had an environmental footprint roughly one-third the size of high meat eaters. Moreover, the study found that even individuals following low meat diets contributed to a reduction in environmental impact by approximately 30% across multiple measures compared to high meat eaters.
The comprehensive assessment considered several critical environmental factors, including greenhouse gas emissions, land use, water use, water pollution, and biodiversity impact.
Lead author, Professor Peter Scarborough, stressed the significance of these findings: ‘Our dietary choices have a big impact on the planet. Cutting down the amount of meat and dairy in your diet can make a big difference to your dietary footprint.’
‘Cherry-picking data on high-impact plant-based food or low-impact meat can obscure the clear relationship between animal-based foods and the environment. But our results use data from over 38,000 farms in over 100 countries. They show that that high meat diets have the biggest impact for many important environmental indicators, including climate change and biodiversity loss. Even in ‘worst case scenarios’ where most foods that are eaten in low meat diets are produced by methods with high environmental impact and most foods that are eaten in high meat diets are produced with low impact methods, low meat diets still have substantially lower environmental impact.’
The study examined the way people actually eat, using data from a sample of 55,000 UK individuals who filled out a food frequency questionnaire. This data was connected to databases that estimate the environmental impacts of multi-ingredient and commonly consumed foods based on a review of 570 Life Cycle Assessment studies, collecting data from 38,000 farms in 119 countries. The research team was able to incorporate variation in where food is from and how it is produced in their estimates of the environmental impact of diets.
All five environmental impacts were correlated with the amount of animal-based food consumed. The impacts of vegans were a quarter of those of high meat eaters for greenhouse gas emissions, and land use, just 27% of the impacts for water pollution, 46% for water use and 34% for biodiversity. At least 30% differences were found between low and high meat eaters for most of the indicators.
The global food system accounted for approximately one-third of total greenhouse gas emissions in 2015. Furthermore, it is estimated that the food system is responsible for 70% of the world's freshwater use and 78% of freshwater pollution. Human use, primarily for agriculture, has affected about three-quarters of ice-free land areas, leading to significant biodiversity loss through deforestation and land use changes.
Previous research has already shown that plant-based diets have lower environmental footprints compared to meat-based diets, and reducing meat intake tends to be healthier. However, these studies often made assumptions about people's food intake and did not consider the variability in environmental impact based on food sourcing and production methods.
The study reinforces past research by emphasising the significantly lower environmental impact of vegan and vegetarian diets compared to meat consumption. Importantly, the region of origin and methods of food production did not obscure the differences between diet groups.
These findings support policy actions aimed at reducing animal-based food consumption, highlighting the potential positive impact of adopting low meat diets on the environment.