The overall goal of food systems is to sustainably provide nutritious and healthy food for everyone at any time. Exploring strategies to achieve this goal and providing guidance on how these strategies can be implemented requires accounting for local conditions (e.g., land, yields, and water availability). This thesis, which mainly focuses on China, explores potential strategies for enhancing nutrient supply in a sustainable and diverse way. It focused on plant-based foods because partially substituting animal-based foods with plant-based foods has the potential to achieve better health and environmental outcomes, and traditional Chinese diets are largely plant-based. Chapter 2 explores strategies from food production, storage, distribution, and processing, to food environments, and consumption in Asia to balance productivity with sustainability, reduce food loss and waste, enhance food quality, and promote a healthy food environment through aligned actions among stakeholders, policy intervention, and investment. Chapter 3 assesses the current role and potential of plant-based foods in China to meet the population’s needs for dietary energy and 17 nutrients. Chapter 4 explores how shifting some rice and wheat areas to underutilized cereals and beans, combined with greater use of whole-grain rice and wheat, can improve nutrient supply and reduce environmental impact. Finally, Chapter 5 evaluates whether utilizable protein supply can be increased through reallocating areas among cereals and beans and expanding maize/soybean intercropped area without compromising other nutritional and environmental outcomes. In this thesis, I integrate evidence from nutrient supply, nutrient intake, and nutrient status to identify nutrient gaps resulting from food system limitations, and I use supply chain modeling and optimization to explore possible solutions that contribute to narrowing these gaps. The modeling results show that area reallocation, intercropping, reducing food loss and waste, reducing red meat intake, and repurposing crop uses have the potential to increase micronutrient and utilizable protein supply and reduce environmental impact in China. The results show to what extent expanding the cultivation of underutilized cereals and beans can simultaneously improve nutrient supply and environmental sustainability. Furthermore, the results show the importance of incorporating protein quality in assessments of protein adequacy and when exploring shifts from animal-based protein to more plant-based protein. Overall, supply-side strategies will require corresponding dietary shifts and vice versa. Integrated analyses that link production, trade, processing, and consumption can guide food system transformations towards better nutrition and environmental outcomes.