Millward D J
Centre for Nutrition and Food Safety, School of Biological Sciences, University of Surrey, Guildford, Surrey GU2 5XH, UK.
J Nutr. 1998 Dec;128(12 Suppl):2563S-2576S. doi: 10.1093/jn/128.12.2563S.
In 1988, Millward and Rivers reappraised existing metabolic models for amino acid requirements. The metabolic demand for amino acids was reviewed in relation to both obligatory metabolic consumption and adaptive pathways of amino acid oxidation. The obligatory demand pattern was deemed unknowable from first principles except that the level of one amino acid would be similar to its concentration in an amount of tissue protein equivalent to the obligatory nitrogen loss. The adaptive demand pattern was predicted to vary in relation to the amount and the periodicity of food protein intake that influenced the amplitude of the diurnal cycle of gains and losses. A regulatory influence of protein intake on anabolism, the anabolic drive, was identified in animal studies; benefit appeared to derive from intakes in excess of the minimum for balance, which could facilitate definition of an optimal requirement. The inherent and design-related limitations of both nitrogen and stable isotope balance studies of requirement were recognized as a major problem in identifying secure values for indispensable amino acid requirements. A decade of research of increasing methodological sophistication has generated much new information, confirming the adaptive diurnal model of balance regulation and allowing development of the anabolic drive into a general protein-stat theory for coordinated control of growth and maintenance of the lean body mass. However, notwithstanding several new estimates of amino acid requirement values, definition of a widely accepted human amino acid requirement pattern remains unresolved. Although a case can be made for an adjusted 1985 FAO adult requirement pattern being a reasonable estimate of the obligatory indispensable amino acid requirements for human maintenance, the problems posed by adaptation, methodological inadequacies and lack of independent measures of adequacy mean that assessment of the adequacy of the human diet to satisfy amino acid needs remains inherently difficult.
1988年，米尔沃德和里弗斯重新评估了现有的氨基酸需求代谢模型。针对氨基酸的代谢需求，从 obligatory 代谢消耗和氨基酸氧化的适应性途径两方面进行了综述。除了一种氨基酸的水平与其在相当于 obligatory 氮损失的一定量组织蛋白中的浓度相似外，从基本原理来看，obligatory 需求模式被认为是不可知的。预计适应性需求模式会因食物蛋白质摄入量的多少和周期性而有所不同，食物蛋白质摄入量会影响每日增减循环的幅度。在动物研究中发现了蛋白质摄入量对合成代谢（即合成代谢驱动力）的调节作用；益处似乎来自于超过平衡所需最小值的摄入量，这有助于确定最佳需求量。需求的氮平衡和稳定同位素平衡研究在本质上以及与设计相关的局限性，被认为是确定必需氨基酸需求安全值的一个主要问题。经过十年方法日益复杂的研究，已经产生了许多新信息，证实了平衡调节的适应性昼夜模型，并使合成代谢驱动力发展成为一种用于协调控制瘦体重生长和维持的通用蛋白质稳态理论。然而，尽管对氨基酸需求值有了几项新的估计，但广泛接受的人类氨基酸需求模式的定义仍未解决。虽然可以认为调整后的1985年粮农组织成人需求模式是对人类维持生命所需必需氨基酸的合理估计，但适应性、方法学不足以及缺乏充足性的独立衡量标准所带来的问题意味着，评估人类饮食满足氨基酸需求的充足性仍然存在固有困难。
