Measuring The Environmental Impacts Of Different Diets

It is well-known that our food system has a substantial impact on the environment and climate change. It is also generally accepted in the research that plant-based diets are less of an environmental burden than diets that contain animal-based foods. A shortcoming in many studies, however, is that most of them are based on modeled dietary scenarios, rather than on true food consumption. 

This study aims to find out the environmental impact of different diets by looking at the actual diets of vegans, vegetarians, fish-eaters, and meat-eaters rather than using artificial models to establish this link. The study also takes into account the differences that individual methods of food production might have on the environment, which other studies often don’t consider.

The researchers used survey data from 65,411 U.K. adults collected between 1993 and 1999. Participants were asked to report on how often they consumed 130 different food items over a 12-month period. Participants who identified as meat-eaters were split into three groups (low, medium, or high) based on their daily meat intake. 

To measure the environmental impact of each diet, the researchers linked the food items from the survey to environmental impact data from a series of Life Cycle Analyses (LCAs) covering 38,000 farms in 119 countries. LCAs measure the environmental impact of each food product from its production to its waste in different categories such as land and water use, GHG emissions, and biodiversity impact. 

The results confirmed that animal-based diets have a bigger environmental impact than other diets. Vegans had less than half of the impact of high meat-eaters for all the environmental factors they studied. There were also large differences among the meat-eater groups. For instance, compared to high meat-eaters, low meat-eaters had 57% of the impact on eutrophication and 44% of the impact on land use. Moreover, these impacts were evident regardless of where a particular food was produced or its method of production.

The dietary data was collected in the 1990s, so dietary preferences are likely to have changed since then. The authors note that an updated study with more current data is necessary. This, for example, may provide clarity on how meat and dairy alternatives have affected the environmental impact of plant-based diets.

As the U.K. and other countries around the world continue to seek sustainable solutions for feeding the global population, the authors argue that discouraging people from eating meat is a must. While animal advocates are always testing out ways to promote plant-based diets, the recommendations from this study include taxing harmful foods and requiring labels to include the environmental impact of a given food product. Both of these strategies are a form of nudging that can be leveraged in advocacy campaigns.