The protein digestibility-corrected amino acid score
The protein digestibility-corrected amino acid score
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DOI：
10.1093/jn/130.7.1865s
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发表时间：
2000-07-01
影响因子：
4.2
通讯作者：
Schaafsma, G
中科院分区：
文献类型：
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作者：
Schaafsma, G
蛋白质消化率校正氨基酸评分（PDCAAS）已被FAO/WHO采用作为测量人类营养中蛋白质价值的首选方法。该方法基于测试蛋白质中第一限制必需氨基酸的浓度与参考（评分）模式中该氨基酸的浓度的比较。这种评分模式源自学龄前儿童的必需氨基酸需求。以这种方式获得的化学分数针对测试蛋白质的真实粪便消化率进行校正。高于 100% 的 PDCAAS 值不被接受，而是被截断为 100%。尽管 PDCAAS 方法的原理已被广泛接受，但科学界对许多问题提出了关键质疑。这些问题涉及1）学龄前儿童氨基酸需要量值的有效性，2）粪便而不是回肠消化率校正的有效性和3）PDCAAS值截断至100％。在采用PDCAAS方法时，仅对学龄前儿童氨基酸需要量进行了少数研究，并且仍然需要对评分模式进行验证。此外，评分模式不包括条件必需的氨基酸。这些氨基酸也有助于蛋白质的营养价值。有强有力的证据表明，回肠消化率（而不是粪便消化率）是校正氨基酸评分的正确参数。使用粪便消化率高估了蛋白质的营养价值，因为进入结肠的氨基酸氮因体内蛋白质合成而损失，并且至少部分以氨的形式从尿液中排出。将 PDCAAS 值截断至 100% 仅适用于将蛋白质用作饮食中唯一蛋白质来源的有限情况。为了评估混合饮食中蛋白质的营养意义，不应使用截断值。在这些情况下，需要更详细地评估蛋白质对混合饮食氨基酸组成的贡献。从这样的评估来看，在谷物饮食中，牛奶蛋白似乎优于植物蛋白。
The protein digestibility-corrected amino acid score (PDCAAS) has been adopted by FAO/WHO as the preferred method for the measurement of the protein value in human nutrition. The method is based on comparison of the concentration of the first limiting essential amino acid in the test protein with the concentration of that amino acid in a reference (scoring) pattern. This scoring pattern is derived from the essential amino acid requirements of the preschool-age child. The chemical score obtained in this way is corrected for true fecal digestibility of the test protein. PDCAAS values higher than 100% are not accepted as such but are truncated to 100%, Although the principle of the PDCAAS method has been widely accepted, critical questions have been raised in the scientific community about a number of issues. These questions relate to 1) the validity of the preschool-age child amino acid requirement values, 2) the validity of correction for fecal instead of ileal digestibility and 3) the truncation of PDCAAS values to 100%, At the time of the adoption of the PDCAAS method, only a few studies had been performed on the amino acid requirements of the preschool-age child, and there is still a need for validation of the scoring pattern. Also, the scoring pattern does not include conditionally indispensable amino acids. These amino acids also contribute to the nutrition value of a protein. There is strong evidence that ileal, and not fecal, digestibility is the right parameter for correction of the amino acid score. The use of fecal digestibility overestimates the nutritional value of a protein, because amino acid nitrogen entering the colon is lost for protein synthesis in the body and is, at least in part, excreted in urine as ammonia. The truncation of PDCAAS values to 100% can be defended only for the limited number of situations in which the protein is to be used as the sole source of protein in the diet. For evaluation of the nutritional significance of proteins as part of mixed diets, the truncated value should not be used. In those cases, a more detailed evaluation of the contribution of the protein to the amino acid composition of the mixed diet is required. From such an evaluation, it appears that milk proteins are superior to plant proteins in cereal-based diets.