Protein Quality Assessment in Human Nutrition
Summary
Protein quality assessment quantifies the capacity of dietary proteins to meet human amino acid requirements and support physiological functions. Historically, in vivo bioassays measured growth responses in animal models, giving rise to indices such as the Protein Efficiency Ratio (PER). More recently, composite scores that integrate amino acid composition and digestibility—namely the Protein Digestibility Corrected Amino Acid Score (PDCAAS) and the Digestible Indispensable Amino Acid Score (DIAAS)—have become preferred tools. These methods account for the proportion of indispensable amino acids that remain available after gastrointestinal processing, reflecting realistic utilisation. Advances in in vitro digestion models, proteomic profiling and stable-isotope tracer studies are refining our ability to predict human responses. Accurate assessment underpins dietary guidelines, informs regulatory claims, guides the formulation of special-purpose foods and supports sustainable shifts towards alternative protein sources.
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Protein Quality Assessment in Human Nutrition publication trend
The graph below shows the total number of articles in protein quality assessment in human nutrition across all publications each year (not limited to Nature Index journals).
Technical terms
Protein Efficiency Ratio (PER): A growth-based index comparing weight gain in animals fed a test protein versus a reference protein.
Protein Digestibility Corrected Amino Acid Score (PDCAAS): A method that adjusts amino acid profiles by true faecal digestibility to yield a score capped at 1.0.
Digestible Indispensable Amino Acid Score (DIAAS): A scoring system that uses ileal digestibility of each indispensable amino acid to calculate a more precise quality metric.
Indispensable amino acids: Amino acids that cannot be synthesised by the body and must be obtained from the diet.
Protein digestibility: The proportion of protein or amino acids that is absorbed and available for metabolic use after gastrointestinal digestion.
References
- Perspective: Assuring the Quality of Protein in Infant Formula. Advances in Nutrition (2023).
- Protein transition: focus on protein quality in sustainable alternative sources. Critical Reviews in Food Science and Nutrition (2024).
- Comprehensive overview of the quality of plant‐ And animal‐sourced proteins based on the digestible indispensable amino acid score. Food Science & Nutrition (2020).
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