Multi-criteria decision analysis (MCDA) as a context-adaptable weighting method for life cycle assessment impact categories in sustainable nutrition science

Current dietary practices are not sustainable to support the growing global population. Environmental sustainability of diets can be indicated by multiple environmental impact categories (EICs). Generic EIC weights may help identify sustainable diets overall but overlook the environmental impact specific to relevant food groups in different contexts. This paper aims to explore if food group specific EIC weighting schemes improve interpretation of overall impact of foods and to assess the suitability of multi-criteria decision analysis (MCDA) for developing such schemes.
First, six EICs and five food groups from the Dutch context were selected for proof of principle (problem structuring). Second, data was normalized using appropriate functional units (scoring alternatives against criteria). Third, a panel of eight Dutch LCA experts answered choice-based questions, facing trade-offs between EICs for each food group (preference modelling).
Greenhouse gas emissions (GHGE) were ranked important across all food groups. Importance of blue water consumption (BWC) and freshwater eutrophication varied depending on the food group. MCDA-based food group weighting schemes have benefits over one generic weighting scheme for food groups with specific (local) environmental challenges (e.g., nuts and seeds with considerable BWC) and for foods with distinct EIC trade-offs (e.g., GHGE and BWC).
EIC weighting for sustainable diets may thus be improved by considering food group specific environmental challenges. MCDA holds valuable potential to learn more about weighting various EICs, considering spatio-temporal and socio-cultural variability in sustainable diets. Future application of MCDA in the sustainable nutrition transition may navigate evolving priorities by incorporating economic or health-related criteria.