Les « dessous » du PD-CAAS et du DIAAS, deux critères en apparence simples de qualité nutritionnelle des protéines
2021
Tessier, Romain | Calvez, Juliane | Gaudichon, Claire
PD-CAAS and DIAAS are indexes that simply reflect protein quality based on protein digestibility and the amino acid composition of the protein relatively to a reference composition. The calculation of these scores raises critical points, among which the amino acid pattern of the reference protein depending on the age range. Moreover, the factor 6.25 used to convert nitrogen to protein to quantify the protein amount in the protein ingredient generally overestimates the protein content, resulting in an underestimation of quality scores. Additionally, using free or “in-chain” molecular weight to estimate amino acids content affects significantly the score. Hence, it is important to clearly specify theses parameters in the studies. Lastly, the model used to determine digestibility (Human, pig, rat) as well as the methodology (ileal vs fecal, assessment of endogenous losses vs isotopic tracers) lead to variability. This must be carefully considered in the understanding of the PD-CAAS and DIAAS and the comparison between protein sources.
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