Determination of Protein Quality of Products Used in Amino Acid Metabolism Diseases with Protein Digestibility-Corrected Amino Acid Score Method: A Descriptive Cross-Sectional Research

Objective: The aim of this study was to evaluate the protein quality of products used in the nutritional treatment of phenylketonuria (PKU) and maple syrup urine disease (MSUD). Material and Methods: Protein digestibility corrected amino acid score (PDCAAS) method was used to evaluate protein quality. Thirty two products including 14 PKU Specialty Products, 5 PKU-glycomacroeptide (PKU-GMP) products and 13 MSUD products were analyzed. Results: PDCAAS scores of PKU products were between 94-100%; PDCAAS scores of PKU-GMP products were between 35- 99%. In general, the limiting amino acids were the sulfur amino acid group with 11 products. The PDCAAS score of MSUD products was between 24-49% and the limiting amino acids of these products were commonly sulfurous amino acid group. Conclusion: Present study revealed that the protein quality and PDCAAS value of PKU specialty products (except PKU-GMP) were generally high. PDCAAS value of PKU-GMP specialty products differed among themselves. The differences between PDCAAS value of PKU-GMP specialty products may attributed to the variability of amino acids supplemented in the products. In MSUD products, protein quality and PDCAAS value were generally lower than PKU specialty products (except PKU-GMP), which related to the limitation of valine, isoleucine, and leucine. Studies on therapeutic foods developed against congenital amino acid disorders are limited; further studies are needed.