Designing Culturally Acceptable, Nutritious, and Low Environmental Impact Finnish Diets with Mycoprotein: A Novel Optimization Approach.

Background: Meat alternatives can support a gradual reduction in meat consumption, contributing to more sustainable diets. Optimization is a useful tool to investigate this potential, but neglecting diet acceptability may limit the relevance of the approach. Objectives: The aim of this study was to develop a new diet optimization model that includes meat alternatives and accounts for diet acceptability, then to apply it to characterize a culturally acceptable, nutritionally adequate, and low-climate impact Finnish diet that incorporates mycoprotein. Methods: An original quadratic optimization model minimizing the weighted distance from the current diet was designed, with mycoprotein introduced as a new food within the meat group. The model first simulated a nutritionally adequate diet including mycoprotein ("NUTR" diet) and then progressively reduced dietary greenhouse gas emissions (GHGEs) while maintaining total consumption of the meat group. Model performance was assessed against a piecewise linear model, and robustness was tested through a sensitivity analysis. Results: The meat group in the "NUTR" diet, which included 27.3 g (5.9 g) of mycoprotein, amounted to 82% (87%) of observed meat consumption for an average adult male (female). For further GHGE reductions, red and processed meats were replaced mainly by poultry, followed by mycoprotein with an increasing share. Imposing large reductions in GHGEs while maintaining meat consumption to its "NUTR" level led to larger adjustments in other food groups and raised potential nutritional concerns, whereas these issues were less pronounced for small to moderate GHGE reductions. Compared with the piecewise linear model, the quadratic formulation was less sensitive to baseline assumptions, yielding more robust and realistic diets. Conclusions: The proposed model advances diet optimization for the study of new foods by incorporating improved considerations of diet acceptability. The Finnish case study illustrates its applicability to simulate climate-friendly, nutritionally adequate diets that integrate mycoprotein, offering a valuable tool for future research on novel foods.