PDCAAS assesses protein quality by considering both amino acid requirements and digestibility. Which option best completes this statement?

• A. Only amino acid profile
• B. Only digestibility
• C. Neither
• D. Both amino acid profile and digestibility

Answer: (D)

PDCAAS combines two essential pieces of information to judge protein quality: how well the protein supplies the indispensable amino acids (the amino acid pattern, including the limiting amino acid) and how well the protein is digested and absorbed by the body. The amino acid score compares the protein’s essential amino acids to human requirements, with the smallest ratio (the limiting amino acid) setting the initial score. Then this score is adjusted by the protein’s digestibility to reflect how much of that amino acid content is actually usable. The final PDCAAS is the product of these two factors, capped at 1.0. Because both the amino acid balance and the digestibility influence how effectively a protein supports nutrition, you get the best measure when you account for both rather than just one or the other.