Protein- and nutrient-normalized environmental footprints of university canteen meals

Background The environmental sustainability of institutional diets is increasingly recognized as a core concern in nutrition science, as food service settings influence population-level dietary patterns. University canteens offer a strategic opportunity to align nutritional quality with environmental sustainability through evidence-based menu planning. Objectives This study assessed the carbon and water footprints of meals served in a large university canteen system using a life cycle assessment (LCA) approach, integrated with nutritional composition analysis and secondary protein-based normalization to inform sustainable diet planning. Methods A total of 150 standardized recipes served in Erciyes University canteens in 2023 were evaluated. Ninety-five individual ingredients were modeled using SimaPro within a cradle-to-kitchen system boundary. Nutritional composition was calculated using the BEBİS database. Environmental impacts were first calculated per standardized serving using a cradle-to-kitchen LCA framework, then compared across meal groups and seasons; additionally, results were secondarily normalized by energy and protein content to explore nutrient-informed environmental efficiency. Results Significant differences were observed among meal groups for both carbon and water footprints ( p 0.001). Meat-based dishes, pastries, desserts, and yogurt-based meals exhibited the highest average carbon footprints (up to approximately 1.4 kg CO₂e per portion), whereas legume-based dishes, salads, olive oil–based vegetable meals, and compotes consistently showed the lowest values (0.4 kg CO₂e). Seasonal variation in carbon footprint was statistically significant but modest ( p = 0.032), with higher values observed in autumn and lower values in summer, while nutritional composition remained relatively stable across seasons. Energy-based normalization reduced between-group differences, whereas protein-based normalization amplified contrasts, identifying legumes as the most environmentally efficient protein sources. Conclusion Meal composition—particularly protein source and nutritional density—is a primary determinant of environmental impact in university food services. Incorporating protein- and nutrient-based normalization into LCA-based environmental assessments represents a conceptual advance by linking environmental performance directly to nutritional function, thereby supporting nutritionally informed strategies for sustainable menu planning in institutional settings.