title: Advantages and limitations of the protein digestibility-corrected amino acid score (PDCAAS) as a method for evaluating protein quality in human diets.
abstract: PDCAAS is a widely used assay for evaluating protein quality. It is a chemical score, which is derived from the ratio between the first limiting amino acid in a test protein and the corresponding amino acid in a reference amino acid pattern and corrected for true faecal N digestibility. Chemical scores exceeding 100 % are truncated to 100 %. The advantages of the PDCAAS are its simplicity and direct relationship to human protein requirements. The limitations are as follows: the reference pattern is based on the minimum amino acid requirements for tissue growth and maintenance and does not necessarily reflect the optimum intake. Truncated PDCAAS of high-quality proteins do not give any information about the power of these proteins to compensate, as a supplement, for low levels of dietary essential amino acids in low-quality proteins. It is likely that faecal N digestibility does not take into account the loss from the colon of indispensable amino acids that were not absorbed in the ileum. Anti-nutritional factors, such as lectins and trypsin inhibitors, in several plant protein sources can cause heightened endogenous losses of amino acids, an issue which is particularly relevant in animal feedstuffs. The assumption that amino acid supplementation can completely restore biological efficiency of the protein source is incorrect since the kinetics of digestion and absorption between supplemented free amino acids and amino acids present in dietary proteins, are different.
authors.affiliation: Research Group on Sports, Nutrition and Lifestyle, Han University, PO Box 6960, 6503 GL Nijmegen, The Netherlands. Gertjan.schaafsma@online.nl
authors.forename: Gertjan
authors.initials: G
authors.lastname: Schaafsma
mesh_terms: D000596:Amino Acids / Q000032:analysis* / Q000378:metabolism; D000601:Amino Acids, Essential / Q000378:metabolism; D000821:Animal Feed; D000818:Animals; D003106:Colon / Q000378:metabolism; D004032:Diet; D004044:Dietary Proteins / Q000032:analysis* / Q000378:metabolism; D019587:Dietary Supplements; D004063:Digestion; D005243:Feces; D006801:Humans; D007082:Ileum / Q000378:metabolism*; D007408:Intestinal Absorption; D009584:Nitrogen / Q000378:metabolism*; D009751:Nutritional Requirements; D009753:Nutritive Value
chemical_list: D000596:Amino Acids; D000601:Amino Acids, Essential; D004044:Dietary Proteins; D009584:Nitrogen