Researchers from University of Granada and the Spanish National Research Council designed four ideal weekly menus with an equal energy value and following international recommendations for the daily intake of a wide range of macro- and micronutrients. Each menu was in accordance with an omnivorous Mediterranean, pesco-vegetarian, ovo-lacto-vegetarian, or vegan diet. The vegan diet reduced carbon emissions by 46%, water use by 7%, and land use by 33%, while the two vegetarian diets cut carbon emissions by up to 35%. The three plant-based diets were nutritionally balanced, except for small deficits in vitamin D, iodine, and vitamin B12, which can be remedied with supplements. The authors concluded that plant-based diets are equally nutritious and healthy as a Mediterranean diet, and much better for the planet.
Only around 1.1% of the world’s population is vegan, but this percentage is growing. For example, in Germany the number of vegans approximately doubled between 2016 and 2020 to 2% of the population, while a 2.4-fold increase between 2023 and 2025 to 4.7% of the population has been reported in the UK. Many people cite health benefits as their reason to go vegan: moving from a typical Western diet to a vegan one can lower the risk of premature mortality from noncommunicable diseases by an estimated 18% to 21%.
Another excellent reason is to reduce your ecological footprint. Now, a study in Frontiers in Nutrition has calculated precisely how much plant-based diets like veganism lower emissions and the use of natural resources. It likewise showed that such diets deliver practically all essential nutrients.
“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.
Rodriguez-Martín and the research team composed four week-long sets of nutritionally balanced daily menus, including breakfast, a mid-morning snack, lunch, and dinner. Each diet was designed to deliver 2,000 kilocalories per day, with servings and a composition based on recommendations of the Spanish Society for Community Nutrition, the Spanish Vegetarian Union, the European Food Safety Authority, and the US National Academy of Medicine.
Healthy lives on a healthy planet
The baseline 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 had been replaced by plant-based alternatives such as tofu, textured soy protein, tempeh, soy yogurt, seeds, or legumes.
The researchers used public databases like the Spanish BEDCA (Base Española de Datos de Composición de Alimentos) and FoodDate Central of the US Department of Agriculture to calculate each menu’s content of macronutrients, as well as of 22 vitamins and essential micronutrients, for example linoleic and linolenic acid, various forms of vitamin B, calcium, iron, and selenium. They compared these with daily intakes as recommended by international health organizations, separately for women and men, either 30 to 51 years old or 51 to 70 years old.
They also estimated the total ecological footprint of each menu, comprising a slew of key ecosystem impact indicators ranging from climate change and ozone depletion to water eutrophication and ecotoxicity, based on the public database AGRIBALYSE 3.1.1.
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The results showed that ‘cradle-to-home’ total greenhouse gas emissions dropped from 3.8kg per day of CO2 equivalents for the omnivorous diet through 3.2kg per day for the pesco-vegetarian diet and 2.6kg per day for the ovo-lacto-vegetarian diet, to 2.1kg per day for the vegan diet – a reduction by 46%.
A similar pattern was found for water use – dropping 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. Interestingly, the vegan diet showed reductions of more than 50% in key ecosystem impact indicators compared to the omnivorous baseline, along with a greater than 55% decrease in disease incidence.
“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.
Food for thought
“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%.”
But for those who wish to help the planet but are not prepared to give up animal-based foods entirely, the authors have an equally important message.
“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.
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