Plant-Based Diets Linked to Lower Mortality and Environmental Impact, Research Finds

Two of the most studied plant-forward diets—the Planetary Health Diet and the Mediterranean Diet—may help people live longer while also lessening their environmental footprint, according to a new study presented at the European Society of Cardiology’s Preventive Cardiology 2025 conference.

Researchers analyzing data from more than 11,000 adults in Spain found that participants with the highest adherence to either dietary pattern were significantly less likely to die during the 14-year follow-up period. The findings add to growing evidence that plant-based eating can simultaneously support public health and environmental sustainability.

Healthier people, healthier planet

“Higher adherence to both diets was similarly associated with lower all-cause mortality and with comparable low environmental impact, highlighting the substantial health and planetary advantages of adopting one of these plant-based diets,” said study author Mercedes Sotos Prieto, PhD of the Autonomous University of Madrid.

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According to the World Health Organization, cardiovascular disease remains the leading cause of death globally, responsible for more than 17 million deaths each year. In Europe alone, poor diet is estimated to contribute to one in five premature deaths. Reducing this burden is central to the mission of preventive cardiology, where food choices play a pivotal role.

Planetary Health Diet

The Planetary Health Diet, introduced in 2019 by the EAT-Lancet Commission, was developed as a blueprint for feeding a growing global population in a way that respects ecological boundaries. It centers meals around whole, plant-based foods—vegetables, fruits, legumes, nuts, whole grains, and unsaturated oils—while recommending limited portions of red meat, added sugars, and high-fat dairy. Caloric intake is capped at roughly 2,500 calories per day, though it varies by individual.

RELATED: What You Eat Now Could Shape Your Future: Harvard Study Links Plant-Based Diets to Healthy Aging

The Mediterranean Diet

The Mediterranean Diet, by contrast, is rooted in the traditional eating patterns of countries bordering the Mediterranean Sea. It also emphasizes plants, favoring fruits, vegetables, legumes, whole grains, and olive oil, while encouraging fish and white meats over red meats. Dairy and eggs are consumed in moderation, with sweets and sugary drinks kept to a minimum.

Scoring the diets

To assess the long-term effects of these diets, researchers turned to the Study on Nutrition and Cardiovascular Risk in Spain (ENRICA), which tracked 11,488 participants aged 18 to 96. Food intake was measured using validated dietary questionnaires. Researchers calculated two separate scores to determine how closely individuals followed each diet: a 0 to 140 point scale for the Planetary Health Diet and a 0 to 14 point MEDAS score for the Mediterranean Diet.

Participants were grouped into tertiles based on adherence. Those in the top third for the Planetary Health Diet had a 22 percent lower risk of death than those in the bottom third. For the Mediterranean Diet, those with the highest adherence saw a 21 percent lower mortality risk.

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In both cases, several individual food components showed independent associations with lower risk. For the Planetary Health Diet, higher consumption of fruits, dairy, and unsaturated oils contributed positively. For the Mediterranean Diet, regular intake of nuts and limited consumption of pastries and sugary sodas were particularly beneficial.

The environmental evaluation added another layer of significance. Using the SHARP-Indicators Database, which assesses greenhouse gas emissions and land use, the study found that both diets had similarly low ecological footprints. The Planetary Health Diet was associated with average daily greenhouse gas emissions of 4.15 kilograms of CO2 and a land use of 5.54 square meters per day. The Mediterranean Diet, including dairy, showed slightly higher greenhouse gas emissions at 4.36 kilograms of CO2 per day but slightly lower land use at 5.43 square meters per day.

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Both diets performed significantly better than conventional Western diets, which typically involve higher consumption of red and processed meat, ultra-processed snacks, and sugar-sweetened beverages—all of which are associated with higher environmental costs. Meat and dairy products were identified as the largest contributors to land and carbon footprints across all dietary patterns studied.

Climate-friendly diets

These results come at a time when public interest in climate-friendly diets is growing. A 2023 report from the UN Environment Programme emphasized that transitioning to more plant-rich diets is essential to meeting global climate targets. The food system currently accounts for over one-third of global greenhouse gas emissions, and livestock alone contributes nearly 15 percent.

Meanwhile, health agencies around the world have begun integrating sustainability into dietary guidance. The Netherlands, Sweden, and Germany have all issued national dietary guidelines that recommend more plant-based foods not just for personal health, but also for the planet.

Spain, where the ENRICA study was conducted, is particularly well-positioned to evaluate the Mediterranean Diet due to its deep cultural roots in the region. However, researchers believe the findings are broadly applicable.

“In 2019, the Planetary Health Diet was developed to optimize global dietary quality while keeping the environmental impacts of food production within sustainable planetary boundaries,” Sotos Prieto said. “However, there was a lack of evidence on how the [Planetary Health Diet] compares with the Mediterranean Diet, a plant-based diet with established health and environmental benefits, that is well rooted in Mediterranean countries. We evaluated the effects of both diets on all-cause mortality and environmental impact in a large representative Spanish population.”

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The research also highlights the feasibility of combining health and environmental goals without requiring radical dietary overhauls. Both diets allow for flexibility, permitting moderate consumption of animal products, which may make them more accessible than strictly vegan or vegetarian plans.

Given the scale of diet-related illness and the urgency of the climate crisis, the alignment between personal and planetary health is no longer theoretical. The evidence is increasingly clear: dietary choices can shape not only individual outcomes, but also the future of global ecosystems.