Vegan Diet Can Cut Your Daily Carbon Footprint Nearly in Half, New Study Shows

A new modelling study published in Frontiers in Nutrition has taken a close, data-driven look at how different dietary patterns impact both environmental footprints and nutrient intake. The results are surprisingly clear: shifting from a typical Mediterranean-style omnivorous diet to a fully vegan one can reduce daily greenhouse-gas emissions by 46%, agricultural land use by 33%, and water use by 7%—even when total calories are kept exactly the same.

This research comes at a time when interest in plant-based eating continues to rise. Only around 1.1% of the global population is currently vegan, but certain regions are seeing rapid growth. Germany, for example, doubled its vegan population between 2016 and 2020, reaching 2%, while the UK reportedly grew from 2% to 4.7% between 2023 and 2025. Many individuals are drawn to plant-based diets for health reasons—moving from a standard Western diet to a vegan diet may reduce the risk of noncommunicable-disease–related early mortality by 18% to 21%. But sustainability is becoming another major motivator.

This new study attempts to quantify exactly how much environmental benefit a shift toward plant-based eating can deliver, and whether such diets truly cover nutritional needs.

How the Researchers Designed the Experiment

The research team, led by Dr. Noelia Rodriguez-Martín of the Spanish National Research Council and now at the University of Granada, created four separate, nutritionally balanced week-long menus. Each menu provided 2,000 kilocalories per day, following portion sizes and nutrient guidelines from major nutrition authorities such as:

The Spanish Society for Community Nutrition
The Spanish Vegetarian Union
The European Food Safety Authority
The U.S. National Academy of Medicine

Every menu included breakfast, a mid-morning snack, lunch, and dinner. The four dietary patterns were:

Mediterranean omnivorous diet – included fruits, vegetables, grains, legumes, fish, poultry, and modest amounts of meat.
Pesco-vegetarian diet – similar to vegetarian eating but included fish and seafood.
Ovo-lacto-vegetarian diet – included eggs and dairy but no fish or meat.
Vegan diet – excluded all animal products; animal foods were replaced with items like tofu, tempeh, legumes, soy yogurt, textured soy protein, and seeds.

The researchers then analyzed the nutrient content of each menu using food-composition databases such as the Spanish BEDCA database and the USDA FoodData Central system. They evaluated macronutrients and 22 key vitamins and minerals—including iron, calcium, selenium, vitamin B variants, linoleic and linolenic acids, and more. They compared these values to international recommendations for men and women aged either 30–51 or 51–70.

To examine environmental impacts, they used AGRIBALYSE 3.1.1, a large database that quantifies environmental effects across categories such as climate change, land occupation, ozone depletion, ecotoxicity, and water eutrophication. Their analysis covered “cradle-to-home,” meaning the entire journey from food production to the point it reaches a consumer’s household.

The Carbon Footprint Results

The findings were direct and striking. Average daily greenhouse-gas emissions were:

3.8 kg CO₂-equivalent for the omnivorous Mediterranean diet
3.2 kg for the pesco-vegetarian diet
2.6 kg for the ovo-lacto-vegetarian diet
2.1 kg for the vegan diet

This represents a 46% drop when comparing omnivorous eating to fully plant-based eating. Even the intermediate diets—pescatarian and vegetarian—showed meaningful reductions of 16% and 32% respectively.

The researchers noted that the vegan diet also showed reductions of more than 50% in several environmental categories beyond carbon emissions. These included certain forms of ecological toxicity, contributions to ozone depletion, and pollution measures tied to agricultural runoff.

Land and Water Use Findings

The environmental improvements weren’t limited to emissions. The study also found significant changes in land and water use.

Land use dropped from a weighted score of 226 in the omnivorous diet to 151 in the vegan diet—a cut of 33%. Since land is heavily used for grazing livestock and producing feed crops, diets containing fewer animal products consistently showed lower land footprints.

Water use, interestingly, changed less dramatically. It declined from 10.2 cubic meters per day to 9.5 cubic meters—a 7% reduction. Although this is smaller than decreases in emissions or land impact, it still represents meaningful savings, especially when scaled to large populations.

Were the Diets Nutritionally Adequate?

All four diets were designed to be nutritionally balanced, and the analysis confirmed that the Mediterranean, pescatarian, vegetarian, and vegan menus met most recommended nutrient intakes. The study reinforces that a vegan diet—when properly planned—can supply all essential macronutrients and almost all essential micronutrients.

However, certain nutrients required more attention in the plant-based menus, especially the vegan one. These included:

Vitamin B12
Vitamin D
Iodine

These are already well-known nutrients of concern in plant-based diets, and the study confirms that people following vegan diets may need fortified foods or supplements. The research also noted that omega-3 fatty acids were low across all diets, including omnivorous ones, indicating that intake of EPA/DHA is a general nutritional issue and not unique to vegans.

Plant-Based Diets Still Show Strong Health Advantages

Beyond environmental impact, the study also reaffirmed the potential health benefits of eating more plant foods. The vegan diet in particular was associated with a greater than 55% reduction in disease incidence (estimated through nutritional modelling). Although this is based on projections rather than a real-world clinical trial, it aligns with broader epidemiological research showing reduced risks of cardiovascular disease, obesity, type-2 diabetes, and other metabolic conditions among people following largely plant-based diets.

Saturated fat levels remained low in all diets—under 8% of daily energy—which supports cardiovascular health. Fiber intake was naturally higher in the plant-based menus, an important factor linked to digestive health and reduced chronic-disease risk.

A Practical Message for People Who Don’t Want to Go Fully Vegan

One important takeaway from the study is that you don’t need to be 100% vegan to make a meaningful environmental difference. Both the pescatarian and vegetarian diets significantly reduced carbon emissions, land use, and pollution levels—but the vegan diet simply had the strongest effect.

In other words, every shift toward more plant-based meals matters. Even reducing meat intake a few days per week can contribute to lower environmental impact and improved personal health over time.

Bigger Picture: Why This Matters

This study contributes to a growing body of research showing that dietary choices have substantial environmental consequences. Food systems account for a significant portion of global greenhouse-gas emissions, and livestock production is one of the most resource-intensive components.

By comparing different diets under equal calorie conditions and using rigorous databases for both nutrition and environmental impact, this study offers a clear, quantified look at how everyday eating patterns contribute to ecological sustainability.

For individuals, the message is simple: more plant foods generally mean a smaller environmental footprint. For governments, the findings reinforce the idea that sustainable dietary guidelines can play a meaningful role in addressing climate goals.

Research Paper Link

Nutrient Adequacy and Environmental Foot-Print of Mediterranean, Pesco-, Ovo-lacto-, and Vegan Menus: A Modelling Study (Frontiers in Nutrition, 2025)
https://www.frontiersin.org/articles/10.3389/fnut.2025.1681512/full