Protein Quality and its Role in Food Systems

Summary

This thesis examines protein quality’s impact on the environmental outcomes of food systems, highlighting the often-overlooked role of digestible indispensable amino acids (IAAs). Chapter 2 identifies the Digestible Indispensable Amino Acid Score (DIAAS) as the best method for assessing protein quality, showing that blending proteins can address amino acid deficiencies. Chapter 3 introduces a new framework that quantifies utilizable amino acids, revealing that up to 70% of absorbed amino acids may be oxidized rather than utilized. Chapter 4 integrates protein digestibility into food systems, showing increased amount of minimal land use with no change in animal-sourced protein (ASP) needs. Chapters 5 and 6 highlight that dietary shifts, such as increased nutritional demands or different distribution of nutritional demands, notably raise land use or emissions – especially when amount of ASP is limited or not included. In summary, optimizing ASP intake (12–21 g/day) can balance nutritional and environmental goals.