Discretionary foods have notable environmental and expenditure relevance regardless of preference for meat or plant-based protein sources

Background and objectives: To understand food groups’ contribution to nutrition, environmental impacts, and expenditure requires self-selected food consumption data. We analyzed implications of a hypothetical transition in protein sources on these sustainability dimensions considering total food consumption. Methods The clusters were derived from food purchase data of 22,901 loyalty card holders by sequence analysis of purchases over 12 months. In a cross-sectional setting, we performed between-cluster comparisons of energy adjusted purchases’ expenditure, LCA-based environmental impacts, and nutrient content. Results Relative to 2500kcal, members of Plant-based and Fish clusters spent the most money on food (9.0-9.8€) and members of Red meat cluster the least (7.4€). The main contributors to the between-cluster differences were not the protein sources themselves. Greenhouse gas emissions were similar in Red meat, Red meat mixed, and Red meat & poultry clusters, but 27–28% lower in Plant-based cluster. Freshwater eutrophication and consumptive water use were the highest in Fish cluster (67% and 25% higher than in Plant-based cluster, respectively). The improvement of micronutrient supplies towards Fish and Plant-based clusters were explained by other foods than protein sources. Discretionary foods had a large contribution to expenditure (22%) and all environmental impacts (17–32%) in all clusters. Conclusions A sustainability transition in protein sources seems affordable for an average Finnish household. Partial replacement of red meat with poultry would offer minimal environmental gains. While fish consumption is nutritionally beneficial, the environmental trade-offs should be carefully considered. Reducing discretionary food consumption could yield notable environmental benefits while reducing household food budgets and improving nutritional quality.