We studied 55,000 people’s dietary data and linked what they ate or drank to five key measures: greenhouse gas emissions, land use, water use, water pollution and biodiversity loss. Our results are now published in Nature Food. We found that vegans have just 30% of the dietary environmental impact of high-meat eaters.
The dietary data came from a major study into cancer and nutrition that has been tracking the same people (about 57,000 in total across the UK) for more than two decades. Those who participated in our study reported what they ate and drank over 12 months and we then classified them into six different groups: vegan, vegetarian, fish-eaters, and low-, medium-, and high-meat-eaters based on their self-reported dietary habits.
We then linked their dietary reports to a dataset containing information on the environmental impact of 57,000 foods. Crucially, the dataset factored in how and where a food is produced – carrots grown in a greenhouse in Spain will have a different impact from those grown in a field in the UK, for instance. This builds on past studies, which tend to assume for example that all types of bread or all steak or all lasagna has the same environmental impact.
By incorporating more detail and nuance, we were able to show with more certainty that different diets have different environmental impacts. We found that even the least sustainable vegan diet was still more environmentally-friendly than the most sustainable meat eater’s diet. In other words, accounting for region of origin and methods of food production does not obscure the differences in the environmental impacts between diet groups.
Read the full story on The Conversation website authored by Michael Clark, Postdoctoral Researcher, Oxford Martin Programme on the Future of Food, University of Oxford and Keren Papier, Senior Nutritional Epidemiologist, University of Oxford.
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