Reeds P J, Hutchens T W
USDA/ARS Children's Nutrition Research, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030.
J Nutr. 1994 Sep;124(9 Suppl):1754S-1764S. doi: 10.1093/jn/124.suppl_9.1754S.
Today because of tools capable of probing the details of metabolism, we are able to study the utilization of amino acids in specific, physiologically important processes. Such information may lead to recommended dietary allowances for each amino acid specific for subpopulations and perhaps individuals. These new findings identify the metabolic end-products of some amino acids as crucial intermediates in the maintenance of a variety of physiological functions that bear no direct relationship to protein metabolism. The precursor amino acids for these intermediate compounds are either non-essential or conditionally essential and thus may play a specific, non-protein, role in amino acid requirements in individuals close to nitrogen equilibrium. Another exciting area arises from the marked dissimilarity between the amino acid composition of milk proteins and other body proteins, suggesting that some milk proteins may have evolved to serve unique functions through specific digestion products. Such products may be important in micronutrient absorption in the neonate. Thus, amino acid requirements appear to reach beyond the tradition areas of nitrogen and protein metabolism.
如今，借助能够探究新陈代谢细节的工具，我们得以研究氨基酸在特定的、具有重要生理意义的过程中的利用情况。此类信息或许能得出针对亚群体乃至个体的每种氨基酸的推荐膳食摄入量。这些新发现表明，某些氨基酸的代谢终产物是维持多种生理功能的关键中间体，而这些生理功能与蛋白质代谢并无直接关联。这些中间化合物的前体氨基酸要么是非必需氨基酸，要么是条件必需氨基酸，因此在接近氮平衡的个体的氨基酸需求中可能发挥特定的非蛋白质作用。另一个令人兴奋的领域源自乳蛋白与其他身体蛋白质的氨基酸组成存在显著差异，这表明某些乳蛋白可能通过特定的消化产物进化出了独特的功能。此类产物可能对新生儿的微量营养素吸收至关重要。因此，氨基酸需求似乎超出了传统的氮和蛋白质代谢领域。
