We know that meat has a huge impact on the planet, and that plant-based foods are more environmentally sustainable. But how much does the food we eat really affect the consequences of the environment and what is the difference of following a vegan diet compared to consuming a high meat, or even a low meat diet?
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 Natural Foods. We found that vegans have only 30% of the environmental impact of eating meat.
The dietary data came from a large study of cancer and nutrition that followed 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 for 12 months and we 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 food reports into a dataset containing information on the environmental impact of 57,000 foods. Most importantly, the data takes into account how and where a food is produced – carrots grown in a greenhouse in Spain have a different effect to those grown in a farm in the UK, for example. This builds on previous studies, which tend to assume for example that all types of bread or all steak or all lasagna have the same environmental impact.
By including more detail and nuance, we were able to show with more certainty that different diets have different environmental effects. We found that even the smallest sustainable vegan diet is more environmentally friendly than the most sustainable meat eater diet. In other words, accounting for the region of origin and methods of food production does not mask differences in environmental impacts between food groups.
Vegans vs. carnivores
Not surprisingly, diets with more animal-based foods have a higher environmental impact. For every unit of food consumed, meat and dairy have anywhere from three to 100 times the environmental impact of plant-based foods.
This can mean a big difference between the two extremes, vegans and high meat-eaters. Vegans in our study had only 25% of the dietary impact of high meat-eaters in terms of greenhouse gas emissions, for example. That’s because meat uses up more land, which means more deforestation and less carbon stored in trees. It uses a lot of fertilizer (usually made from fossil fuels) to feed the plants that feed the animals. And because cows and other animals directly emit gases themselves.
It’s not just emissions. Compared to high meat eaters, vegans also have only 25% of the food impact for land use, 46% for water use, 27% for water pollution and 34% for biodiversity.
Even low-meat diets have only about 70% of the impact on most environmental measures of high-meat diets. This is important: you don’t have to go full vegan or even vegetarian to make a big difference.
Global impact
These findings are important because the food system is estimated to be responsible for nearly 30% of global greenhouse gas emissions, 70% of global freshwater use and 78% of freshwater pollution. About three quarters of the world’s ice-free land has been affected by human use, especially for agriculture and land use change such as deforestation which is a major source of biodiversity loss.
In the UK, meat consumption has declined over the decade to 2018, but to meet environmental targets the National Food Strategy and the UK’s Climate Change Committee recommend a further 30%-35% reduction.
The choices we make about what we eat are personal. These are habits that are so ingrained that they can be difficult to change. But our study and others continue to strengthen the evidence that the food system has a huge global impact on the environment and health that can be reduced by a shift towards more plant-based diets. We hope our work inspires policy makers to take action and people to make more sustainable choices while still eating nutritious, affordable and delicious food.
Provided by The Conversation
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Citation: Vegan diet has only 30% the environmental impact of a high-meat diet, major study finds (2023, July 24) retrieved on July 24, 2023 from https://phys.org/news/2023-07-vegan-diet-environmental-impact-high-meat.html
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