We know that meat has a significant impact on the planet and that plant-based diets are more environmentally sustainable. But how exactly does the food we eat affect the environment, and what difference will it make after a vegan diet compared to a high or even low-meat diet?

We looked at dietary data from 55,000 people and correlated what they ate or drank with five key indicators: greenhouse gas emissions, land use, water use, water pollution, and biodiversity loss.

Our results are now published Nature Food . We found that vegans account for only 30% of the environmental impact on the diet of those who eat a lot of meat. The dietary data came from the Large Cancer and Nutrition Study, which followed the same people (about 57,000 total in the UK) for over two decades.

The people in our study reported what they ate and drank over a 12-month period, and then we divided them into six different groups: vegans, vegetarians, fish eaters, and low-, moderate-, and high-meat eaters, according to their eating habits.

We then linked the diet reports to a dataset containing information on the environmental impact of 57,000 foods. More importantly, the dataset takes into account how and where food is produced – for example, carrots grown in a greenhouse in Spain will have a different effect than carrots grown in a field in the UK.

This is based on past research that generally assumes that all types of bread, all steaks, or all types of lasagna, for example, have the same environmental impact. By adding more details and nuances, we were able to show with greater confidence that different diets have different effects on the environment.

We have found that even the least sustainable vegan diet is more sustainable than the most sustainable carnivore diet. In other words, considering region of origin and food production methods does not mask differences in environmental impact between diet groups.

Vegans vs. carnivores

Not surprisingly, diets higher in animal products had a greater environmental impact. Meat and dairy products per unit of food consumed have three to 100 times more impact on the environment than plant-based products.

This can mean a big difference between the two extremes, vegans and carnivores. For example, the vegans in our study had only 25% of the dietary impact of those who ate a lot of meat in terms of greenhouse gas emissions.

This is because meat uses more land, which means more deforestation and less carbon stored in trees. It uses large amounts of fertilizer (usually produced from fossil fuels) to feed the plants that feed the animals. And because cows and other animals directly emit gas themselves.

It’s not just emissions. Compared to those who ate a lot of meat, vegans also had a diet impact of only 25% on land use, 46% on water use, 27% on water pollution and 34% on biodiversity.

Even low-meat diets had only about 70% of the effect on most environmental indicators of high-meat diets. This is important: you don’t have to be completely vegan or even vegetarian to make a big difference.

global impact

These findings are critical because the food system is estimated to be responsible for around 30% of global greenhouse gas emissions, 70% of the world’s freshwater use, and 78% of freshwater pollution.

About three-quarters of the world’s ice-free land has been affected by human use, particularly agriculture and land use changes such as deforestation, which is a major source of biodiversity loss.

Meat consumption in the UK has fallen in a decade to 2018, but the National Food Strategy and the UK Climate Change Committee are recommending further reductions of 30-35% to meet environmental targets.

The choices we make about what we eat are personal. These are very ingrained habits that are difficult to change. But our research and others continue to strengthen the evidence that the food system has an enormous global impact on the environment and health that can be reduced by switching to a more plant-based diet.

We hope our work will mobilize politicians and inspire people to make greener choices while eating something nutritious, affordable and delicious. Source