This study, a deliverable of the Horizon Europe PLAN'EAT Project, presents a comprehensive evaluation of the environmental and health impacts, social risks, and hidden costs associated with different dietary patterns across three European countries, using the True Cost Accounting (TCA) method. Focusing on three Living Labs—in Germany, Ireland, and France—the research compares the true costs of the average diets in these countries with both their respective national dietary recommendations and the Planetary Health Diet. By identifying the key contributors to external costs and social risks (“hotspots”) within each diet, this study highlights the most impactful levers for driving sustainable dietary transitions in each country. Additionally, the affordability of each dietary pattern is assessed by examining the share of household income required to meet the respective dietary costs, offering insights into their economic feasibility.

Transitioning to the Planetary Health Diet would bring substantial health benefits in all three countries by reducing consumption of red meat and dairy. To reduce environmental impacts driven by land use, pollution, and greenhouse gas emissions, the Planetary Health Diet would be the best option in Ireland and France, while in Germany the national dietary guidelines would create the lowest environmental costs. All assessed diets, including the Planetary Health Diet, do have some social risks associated with production conditions of certain plant foods. These risks can be reduced or mitigated by opting for socially certified products or sourcing from countries with high labour and human rights standards. Despite regional variations, the results consistently show that health and environmental performance are closely aligned, suggesting no trade-off between sustainability and health. Red and processed meat and some dairy products (e.g. cheese) have the highest hidden costs, meaning that a shift towards plant-based diets benefits both people and the planet. The assessed diets are generally affordable across all three countries, though the Planetary Health Diet is the most expensive and would pose a greater financial burden for lowest-income groups.