Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, The Netherlands.
Curr Opin Clin Nutr Metab Care. 2012 Jan;15(1):71-7. doi: 10.1097/MCO.0b013e32834d617a.
Amino acids do not merely represent precursors for de-novo protein synthesis, but also function as nutritional signals regulating various metabolic processes. In fact, ample evidence has been generated to show that various tissues respond to changes in amino acid availability via signal transduction pathways that are also regulated by hormones such as insulin, glucagon, and insulin-like growth factor 1.
Amino acids, and leucine in particular, can act as strong insulin secretagogues when administered in combination with carbohydrate. Leucine administration can be applied effectively to improve postprandial glycemic control. Furthermore, amino acids have been shown to stimulate mRNA translation, thereby increasing muscle protein synthesis and stimulating net protein accretion in an insulin-independent manner. These anabolic properties of amino acids have been mainly attributed to the essential amino acids, and leucine in particular. In accordance, the recent in-vivo human studies show that leucine ingestion can augment the blunted muscle protein synthetic response to protein or amino acid ingestion in elderly men.
Leucine has been proposed as a promising pharmaconutrient in the prevention and treatment of sarcopenia and/or type 2 diabetes. Though there are numerous applications for the proposed benefits of leucine in health and disease, the recent long-term nutritional intervention studies do not confirm the clinical efficacy of leucine as a pharmaconutrient.
氨基酸不仅是合成蛋白质的前体，还作为营养信号调节各种代谢过程。事实上，大量证据表明，各种组织通过激素（如胰岛素、胰高血糖素和胰岛素样生长因子 1）调节的信号转导途径对氨基酸可用性的变化做出反应。
当与碳水化合物联合使用时，氨基酸，尤其是亮氨酸，可以作为强烈的胰岛素分泌剂。亮氨酸的应用可以有效地改善餐后血糖控制。此外，氨基酸已被证明可以刺激 mRNA 翻译，从而增加肌肉蛋白质合成并以不依赖胰岛素的方式刺激净蛋白积累。这些氨基酸的合成代谢特性主要归因于必需氨基酸，尤其是亮氨酸。相应地，最近的人体体内研究表明，亮氨酸摄入可以增加老年男性对蛋白质或氨基酸摄入时肌肉蛋白质合成反应的迟钝。
亮氨酸已被提议作为预防和治疗肌肉减少症和/或 2 型糖尿病的有前途的药物营养素。虽然亮氨酸在健康和疾病方面有许多应用，但最近的长期营养干预研究并不能证实亮氨酸作为药物营养素的临床疗效。
