The protein digestibility-corrected amino acid score

Area of Science:

• Nutritional biochemistry
• Human nutrition
• Food science

Background:

• The protein digestibility-corrected amino acid score (PDCAAS) is the FAO/WHO preferred method for assessing protein value in human nutrition.
• It compares a test protein's limiting amino acid to a reference pattern derived from preschool-age children's requirements.
• The score is corrected for fecal digestibility and truncated at 100%.

Purpose of the Study:

• To critically evaluate the scientific basis and limitations of the PDCAAS method.
• To address concerns regarding the amino acid requirement values, digestibility correction, and score truncation.

Main Methods:

• Review of existing scientific literature and data on amino acid requirements and protein digestibility.
• Analysis of the validity of the preschool-age child amino acid scoring pattern.
• Comparison of fecal versus ileal digestibility for protein quality assessment.

Main Results:

• The scoring pattern's validity needs further validation, and it omits conditionally indispensable amino acids.
• Ileal digestibility is a more accurate parameter than fecal digestibility for correcting amino acid scores.
• Truncation of PDCAAS values to 100% is inappropriate for mixed diets, potentially overestimating protein quality.

Conclusions:

• The PDCAAS method has significant limitations requiring scientific re-evaluation.
• Ileal digestibility correction and avoiding score truncation are crucial for accurate protein nutritional value assessment.
• Milk proteins demonstrate superior nutritional value compared to plant proteins in cereal-based diets.