Vegan diet cuts carbon emissions by 46% and land use by 33%, while still delivering virtually all essential nutrients, according to a study published in the journal Frontiers in Nutrition.
About 1% of the world’s population is vegan, and this figure is increasing as more people move from a typical Western diet to a vegan diet to lower their risk of premature mortality.
Some people also choose a vegan diet for environmental reasons. To confirm the benefits, a team from the University of Granada, Spain, calculated how much plant-based diets lower emissions and reduce the use of natural resources. “We compared diets with the same amount of calories and found that moving from a Mediterranean to a vegan diet generated 46% less CO2 while using 33% less land and 7% less water, and also lowered other pollutants linked to global warming,” said Dr Noelia Rodriguez-Martín, a postdoctoral researcher at the Instituto de la Grasa of the Spanish National Research Council now based at the University of Granada, and the corresponding author of the new study.
For this work, the authors collated four week-long sets of nutritionally balanced daily menus, including breakfast, a mid-morning snack, lunch, and dinner. Each diet delivers 2,000 kilocalories per day and follows recommendations from the Spanish Society for Community Nutrition, the Spanish Vegetarian Union, the European Food Safety Authority, and the US National Academy of Medicine.
The base diet was a healthy omnivorous Mediterranean diet, rich in fruits and vegetables, whole grains, and lean protein, with moderate amounts of fish, poultry, and meat. Two others were pesco-vegetarian and ovo-lacto-vegetarian, respectively, including fish and seafood or eggs and dairy, but without meat. The fourth was vegan, where all animal-based foods were replaced by plant-based alternatives such as tofu, textured soy protein, tempeh, soy yogurt, seeds, or legumes.
The authors then estimated the total ecological footprint for each menu, including a series of key indicators ranging from climate change and ozone depletion to water eutrophication and ecotoxicity.
The results showed that total greenhouse gas emissions decreased from 3.8kg per day of CO2 equivalents for the omnivorous diet to 3.2kg per day for the pesco-vegetarian diet, 2.6kg per day for the ovo-lacto-vegetarian diet, and 2.1kg per day for the vegan diet – a total reduction of 46%.
The team found a similar pattern for water use – values dropped by 7% from 10.2 cubic meters of water for the omnivorous diet to 9.5 cubic meters for the vegan diet – and for agricultural land occupation, falling by 33% from 226 to 151 points on a weighted environmental impact score associated with land use, expressed per day of diet.
“Our analyses showed that all three plant-based menus were nutritionally balanced, with only vitamin D, iodine, and vitamin B12 needing a bit more attention. Overall, the indicators clearly highlight the environmental and health advantages of plant-based diets compared with the omnivorous baseline,” said Rodriguez-Martín. “But in our four-way comparison – omnivorous, pesco-vegetarian, ovo-lacto-vegetarian and vegan – the pattern was clear: the more plant foods, the smaller the ecological footprint. The pesco-vegetarian menu showed moderate gains, though fish production adds some environmental costs. Vegetarian diets also performed well, cutting carbon emissions by about 35%.”
Despite these results, the authors have an important message for those who wish to help the planet but are not prepared to give up animal-based foods entirely: “You don’t need to go fully vegan to make a difference. Even small steps toward a more plant-based diet reduce emissions and save resources. Every meal that includes more plants helps move us toward healthier people and a healthier planet,” concluded Rodriguez-Martín.
Alcalá-Santiago A, Rodríguez-Martín N, Casas-Albertos E te al. Nutrient adequacy and environmental foot-print of Mediterranean, pesco-, ovo-lacto-, and vegan menus: a modelling study. Front. Nutr., Volume 12 – 2025 | https://doi.org/10.3389/fnut.2025.1681512