A new study conducted by the University of Granada and the Spanish National Research Council has compared the carbon footprints of four diets — omnivorous Mediterranean, pesco-vegetarian, ovo-lacto-vegetarian, and vegan.
The researchers looked at key ecosystem impact indicators such as climate change, ozone depletion, water eutrophication, and ecotoxicity, based on the public database AGRIBALYSE 3.1.1. They found that “cradle-to-home” total greenhouse gas emissions dropped from 3.8kg per day of CO2 equivalents for the omnivorous diet to 3.2kg for the pesco-vegetarian diet, 2.6kg for the ovo-lacto-vegetarian diet, and 2.1kg for the vegan diet. This represents a 46% reduction.
Water use dropped by 7% from 10.2 cubic meters of water for the omnivorous diet to 9.5 cubic meters for the vegan diet. Agricultural land occupation fell by 33% from 226 to 151 points on a weighted environmental impact score associated with land use. Additionally, the vegan diet led to 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.
Photo: Tim Mossholder on Pexels
“The more plant foods, the smaller the ecological footprint”
The research team composed four week-long sets of nutritionally balanced daily menus for each diet, all delivering 2000 kilocalories per day. Using public databases like the Spanish BEDCA (Base Española de Datos de Composición de Alimentos) and FoodDate Central by the US Department of Agriculture, they calculated each menu’s macronutrient, essential micronutrient, and vitamin content. These were compared with daily intakes as recommended by international health organizations.
The meat-free diets were all found to be nutritionally balanced, except for small deficits in vitamin D, iodine, and vitamin B12 that could easily be remedied with supplements. The researchers conclude that plant-based diets are equally as nutritious and healthy as the Mediterranean diet, and much better for the planet.
The publication of the study comes after the recent EAT-Lancet Commission report found that transforming food systems could cut greenhouse gas emissions from food by more than half. The report also concluded that shifting diets to include more whole plant foods, along with fewer animal products, refined sugars, and processed foods, could prevent up to 15 million premature deaths per year.
“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,” said Dr Noelia Rodriguez-Martín, a postdoctoral researcher at the Instituto de la Grasa of the Spanish National Research Council and the corresponding author of the new study. “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.”
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