Which metric is commonly used to assess protein quality?

• A. PDCAAS
• B. Biological value (BV)
• C. Protein efficiency ratio (PER)
• D. Digestible indispensable amino acid score (DIAAS)

Answer: (A)

Protein quality is determined by how well a protein supplies the essential amino acids our bodies require and how well it is digested and absorbed. PDCAAS, or Protein Digestibility-Corrected Amino Acid Score, combines two key ideas: the amino acid pattern of the protein (which essential amino acids are present and in what amounts, with the lowest-supply amino acid called the limiting amino acid) and how much of the protein is digested and made available to the body. You take the amino acid score based on the limiting essential amino acid, adjust it by the protein’s digestibility, and then cap the result at 1.0 (100%). This makes PDCAAS a practical and widely used measure for judging protein quality in nutrition labeling and guidelines.

DIAAS is a newer method that offers a more precise assessment by looking at the digestibility of essential amino acids at the ileal level, and it isn’t yet as universally adopted as PDCAAS. Other older measures like Biological Value or Protein Efficiency Ratio focus less directly on how well human essential amino acid needs are met, so they’re not as commonly used for evaluating protein quality in humans.