Large-scale dietary shifts are crucial for sustainable food systems within planetary boundaries while ensuring nutritious diets for a growing population. Numerous studies indicate that globally, plant-based diets can mitigate environmental pressures and improve public health. These studies often focus on replacing ASFs with WFs like legumes. However, consumer resistance to such shifts exists due to factors like taste, convenience, and cultural preferences for ASFs. To overcome these barriers, PBAs, processed foods mimicking ASFs, offer an alternative. While PBAs often use WFs as a base, processing and sensory properties differ. PBAs are promoted for their potential to mitigate environmental impacts, improve animal welfare, and address nutritional and health concerns associated with ASFs. Several life cycle assessments (LCAs) show PBAs to be more environmentally sustainable than their ASF counterparts but less so than unprocessed WFs. Nutritional impacts remain uncertain, with some studies questioning their benefits while others highlighting their superiority to processed ASFs. The availability of PBAs has drastically increased in recent years, making it necessary to empirically assess the broad sustainability implications (environmental, nutritional, and socioeconomic) of increased PBA consumption. The study utilizes Sweden as a case study because of its high per capita ASF consumption, considerable environmental and epidemiological burden from its current diet, and a growing PBA market.

Existing literature highlights the urgent need for dietary changes to achieve sustainable food systems while ensuring public health. Global modeling studies have consistently shown that shifting to plant-based diets can significantly reduce the environmental footprint of food systems. These studies often analyze scenarios where ASFs are replaced by WFs, but consumer studies reveal significant barriers to adopting such diets, including taste, convenience, and cultural preferences for ASFs. To address these challenges, PBAs are proposed as an alternative, offering processed plant-based options that mimic the sensory attributes of ASFs. While the sustainability and potential health benefits of individual PBAs have been investigated through LCA studies, there is a lack of comprehensive analysis of the overall sustainability implications of incorporating PBAs into complete diets at a national level, comparing them not just with ASFs but also with WFs. This study aims to fill this gap by conducting a comprehensive analysis of the environmental, nutritional and economic implications of incorporating PBAs in the Swedish diet.

This modeling study employed a multi-indicator analysis to evaluate the environmental, nutritional, and economic impacts of dietary changes in Sweden. The study began by establishing a baseline diet (BAU) based on national food consumption data, accounting for food loss and waste. Six dietary scenarios were then created, substituting ASFs with either PBAs or WFs: vegan (all ASFs replaced by PBAs or WFs), vegetarian (meat and seafood replaced), and flexitarian (50% ASF replacement). Two functional units, mass (grams) and energy (kcal), were utilized for each scenario to address uncertainties associated with functional unit selection. Nutritional analysis involved comparing the nutrient composition of each scenario to the Nordic Nutrition Recommendations, focusing on macro- and micronutrients relevant to Swedish health conditions. Environmental impact assessment focused on greenhouse gas emissions (GHGe), land use (LU), and freshwater use (WU), using LCA data from various sources. Finally, daily food expenditure was calculated based on retail prices from a major Swedish retailer. Uncertainty analysis was conducted using both functional units (mass and energy) and by accounting for price and nutrient variability within food categories. The results were compared with national data on food expenditure to provide a comprehensive assessment.

The study's nutritional analysis showed improvements in several key areas across all six scenarios compared to the BAU diet, with increased iron, fiber, folate, magnesium, and polyunsaturated fats and decreased saturated fats. However, deficiencies in vitamin B12, vitamin D, and selenium were observed in some scenarios, particularly vegan diets. Protein and zinc intake met or exceeded recommendations in all scenarios but decreased compared to the BAU. The environmental analysis revealed significant reductions in GHGe, LU, and WU across all plant-based scenarios compared to the BAU. Vegan diets using either PBAs or WFs yielded the greatest reductions (50-56% GHGe, 32-44% LU), followed by vegetarian and then flexitarian diets. ASF consumption was identified as the biggest contributor to environmental impacts in the BAU diet, with meat products leading the way. In the vegan PBA scenario, PB snacks (largely due to dark chocolate) became the largest contributors to GHGe. Regarding daily food expenditure, PBA scenarios showed a slight increase (3-5%), while WF scenarios resulted in decreases (4-17%). The largest cost reduction was seen in the vegetarian WF scenario. Uncertainty analyses, using both mass and energy units and considering internal variability within food types, showed consistent results although the energy based analysis increased GHGe slightly (7-23%), particularly in the WF scenarios. High price variations, especially for seafood, were also revealed.

The study's findings confirm that transitioning to plant-based diets, using either PBAs or WFs, offers significant environmental benefits while mostly meeting nutritional recommendations. While some micronutrient deficiencies emerged, particularly with vitamin B12, vitamin D, and selenium, these are potentially addressable through supplementation or PBA fortification. The observed slight increase in cost for PBA diets compared to WF diets could be mitigated by purchasing cheaper options within the range of available products. The substantial reduction in environmental impacts from reducing ASF consumption (compared to the choice between PBAs and WFs) suggests that these strategies are complementary and should target different consumer groups. The slight underestimation of food expenditure compared to national data is likely due to the use of prices from a discount retailer and the exclusion of household food waste from calculations. Socioeconomic factors and consumer acceptance will play crucial roles in the success of any dietary shift. Future research needs to address these gaps.

This study demonstrates that shifting to plant-based diets using either PBAs or WFs can significantly reduce the environmental impact of the Swedish diet while largely meeting nutritional requirements and remaining cost-competitive. Minimizing ASF consumption is emphasized as the most impactful approach. However, consumer preferences and socioeconomic factors remain critical considerations for future research and the successful implementation of dietary transitions. Future research should focus on improving the nutritional profile of PBAs (e.g., reducing sodium content), assessing nutrient bioavailability, and exploring the sociocultural and economic factors impacting dietary choices, particularly concerning affordability.

Several limitations exist, primarily related to data availability. Consumption data for PBAs and tofu were unavailable in the national database, necessitating assumptions about their intake in the BAU diet. Limited LCA data for some PBAs required using proxy values. The environmental impact assessment was limited to GHGe, LU, and WU due to data constraints. The study also did not account for the bioavailability of fortified nutrients in PBAs, nor did it stratify the results by various demographic groups. These limitations should be addressed in future research.