The role of alternative proteins and future foods in sustainable and contextually-adapted flexitarian diets

Devising contextually adapted and sustainable flexitarian diets that integrate alternative proteins and future foods can support sustainable food systems. In this commentary, we critically evaluate the role of alternative proteins and future foods (i.e., microalgae, insects, fungi, cultured meat, and plant-based meat) with respect to tradeoffs between animal- and plant-sourced foods in future flexitarian diets. We focus on four key sustainability dimensions: environmental impacts, nutrition/health, animal welfare, and antibiotic use. We further explore the differentiated role of meat products (e.g., chicken vs. beef), in addition to production practices that simultaneously increase nutrient contents while decreasing environmental impacts. Finally, we illustrate why and how context-specific conditions, namely, environmental, nutritional/health, access, culture, and knowledge boundaries, should be considered when developing these diets. The role of alternative proteins in sustainable flexitarian diets is highly variable depending on the food item and production method (e.g., feed substrate, processing technology). Furthermore, environmental tradeoffs exist (e.g., low land use but high energy demand) as well as nutritional gaps including a lack of certainty regarding nutritional equivalency claims from future foods when compared to their contemporary counterparts. Moreover, strong uncertainties regarding nutrient absorption (e.g., bioavailability) and activity in the body exist. Animal welfare and antibiotic use concerns have the potential to be strongly mitigated with the introduction of alternative proteins. Finally, more standardized and robust sustainability assessments are needed. Overall, future foods hold promise to support sustainable and contextually-adapted flexitarian diets, but significant work and understanding are still needed. •The role of future foods in sustainable flexitarian diets is critically examined.•Key environmental tradeoffs of future foods include energy demand versus land use.•Large variations in production practices produce variable sustainability outcomes.•Nutrient variability across future foods is high.•Context-specific boundaries are key in defining appropriate flexitarian diets.