A Scoping Review of the How Evidence on Essential Amino Acid Requirements and Protein Quality is Incorporated into Dietary Guidance, Equivalence Frameworks, Labelling, and Policy

Dietary protein guidance, food equivalence frameworks, and labelling regulations play a central role in shaping population protein intake and food choices. However, the extent to which current guidance reflects the best available evidence on essential amino acid (EAA) requirements and protein quality, including digestibility and metabolic availability, across the lifespan is unclear. There is growing concern that existing frameworks may not adequately account for differences between protein sources in amino acid composition, digestibility, and bioavailability, particularly as dietary patterns shift toward plant-based foods. A scoping review is the appropriate methodology for this question because the evidence spans four substantively different evidence types: interventional metabolic research, measurement science, food equivalence frameworks, and policy/regulatory documents. A traditional systematic review framework would inappropriately exclude the non-interventional evidence critical to the overarching research question. The goal of this review is to map the breadth, nature, and gaps in the evidence base, not to synthesise effect estimates.