Identifying the most sustainable foods using two different approaches: a priori versus a posteriori

Abstract

Objectives: To identify the most sustainable foods by using both an a priori sustainability score and a posteriori cluster analysis, comparing the results across key sustainability dimensions. Methods: Data were sourced from 2553 Portuguese adults (18+ years) who completed two non-consecutive 24-h recalls during the most recent National Food, Nutrition and Physical Activity Survey of 2015-2016. Culturally acceptable food items were selected for analysis (based on consumption frequency and quantity) and evaluated for health-related nutritional attributes (NOVA-classification and Nutrient-Rich Food Index 9.3), environmental impact (greenhouse-gas emissions and land use from the SHARP-Indicators Database) and cost (retail prices). The a priori approach used a sustainability score, while the a posteriori approach employed cluster analysis. Results: A total of 366 food items were selected as culturally acceptable (covering 75% of total daily energy intake). Both methods identified sustainable foods as those that combine high nutrient-density and low processing levels with low environmental impact and cost. The a priori approach identified 96 items as sustainable, while the a posteriori analysis revealed 144 items, showing variations in food categories. Unprocessed and minimally processed foods were prevalent in both methods, but the a posteriori approach yielded a higher proportion. Nutrient-richness, environmental impact and cost were significantly better for the most sustainable foods in both approaches. Conclusion: These findings underscore the importance of using multiple methods to capture the complexity of food choices in the context of sustainability, offering insights for developing sustainable dietary guidelines that balance health-related nutritional, environmental and economic factors.