Product-group-specific nutrient index as a nutritional functional unit for the Life Cycle Assessment of protein-rich foods

Purpose Substitution of animal-source foods with plant-based alternatives requires product-specific information from both the environmental and nutritional perspectives. The use of nutrient indices as nutritional functional units (nFUs) in Life Cycle Assessment (LCA) of food products has been developed to integrate nutritional aspects into the method (nLCA). However, the methodological approaches vary because the execution of LCA always depends on context. Methods We present a methodological approach for the nLCA of protein-rich foods with a product-group-specific nFU, as update to earlier development work. We compared three strategies for selecting nutrients to be included in the nFU index for protein-rich foods in a national context, considering Finnish nutrition recommendations to different age groups, and the population’s dietary habits and nutrient intake. nFUs were demonstrated through cradle-to-plate LCA for foods made with beef, pork, broiler, trout, perch, chickpea, soya mince, and pulled oats as the main ingredients. Results The selected strategies to format the nFU have a marked impact on the results especially for fish- and plant-based food. The results of each population group, especially children, also differ. The choice of nutrients in the index, the type of food assessed, and the system boundaries of assessment have a considerable impact on the results. Conclusion The baseline nFU introduced in the study is valuable in producing sustainability information to support the aspiration to a sustainable dietary shift. The index used as the nFU should be formatted based on the study goal and scope, and vulnerable groups must be considered when interpreting the results.