Nutritional Life Cycle Assessment of Cow Milk in Northern Italy: Implications for Comparisons with Plant-Based Alternatives

This study evaluated the environmental impact of milk production in Northern Italy using a nutrient life cycle assessment (nLCA) approach with different functional units (FUs) related to the nutritional value of whole milk at the farm gate. Data from 94 dairy farms in the production areas of two protected designations of origin (PDOs) were analyzed. The FUs considered were based on milk mass, protein, calcium, essential amino acids (EAA), portion size, and milk energy content. Climate change (CC) impact was assessed using Intergovernmental Panel on Climate Change (IPCC) guidelines. The assessment estimated environmental impacts of 0.17, 4.78, 0.14, 1.06, 0.21, and 0.33 kg CO2-eq for the FUs: 100 g of milk, 100 g of protein, 100 mg of calcium, 10 g of EAA, 125 mL portion size, and 100 kcal of milk, respectively. Results showed no significant differences in CC between PDOs and geographical areas (plain vs. mountain) for any selected FU. However, when comparing cow milk with plant-based alternatives, product ranking changed substantially depending on the selected FU: while milk showed the highest impact per 100 g product, its relative performance improved when expressed per 100 g protein. These findings demonstrate that FU choice influences the interpretation of environmental results.