Our transition towards sustainable food systems includes both changes in how we produce our food, but also in the type of food products we consume. While environmental impact often takes center stage in these discussions and nutritional value may also be included, affordability of foods and diets should never be ignored. Affordability of diets is very context dependent and really necessitates the consideration of local contexts. I.e., in affluent Western countries certain products may fit in diets but they may not fit is less affluent areas in e.g., South East Asia or Sub-Saharan Africa. By combining understanding of local nutritional status and nutritional gaps, local consumption patterns and economic status, the most suitable products can be made to supplement local diets. Linear programming approaches sustainable, affordable and healthy diets can be modelled. Outcomes of such models clearly indicate the importance of nutrient-rich affordable products, including e.g., milk, in diets. Food products should fit in sustainable diets, which does not only mean nutritious products with limited environmental impact, but also affordable products. Combining these aspects provides opportunities and challenges, which should be balanced: what is possible, what is practical and what is optimal. Speaker: Thom Huppertz, PhD