Georg Hoffmann, PhD, Department of Nutritional Sciences, Faculty of Life Sciences, University of Vienna, Althanstreet 14 (UZAII), A-1090 Vienna, Austria, M:
J Nutr Health Aging. 2015 Apr;19(4):437-46. doi: 10.1007/s12603-014-0559-4.
The primary objective of the present systematic review and meta-analysis was to synthesize the available literature relating to leucine supplementation in the elderly with respect to its effects on anthropometrical parameters and muscle strength. The secondary aim was to perform a selective subgroup analysis when possible differentiating between healthy and sarcopenic subjects.
Literature search was performed using the electronic databases MEDLINE, EMBASE, SportDiscus, and the Cochrane Central Register of trials with restrictions to randomized controlled trials or studies following a cross-over design. Parameters taken into account were body weight, body mass index, lean body mass, fat mass, percentage of body fat, hand grip strength, and knee extension strength. Moreover, biomarkers of glucose metabolism (fasting glucose, fasting insulin, albumin, and HOMA index) were extracted when possible. For each outcome measure of interest, a meta-analysis was performed in order to determine the pooled effect of the intervention in terms of weighted mean differences between the post-intervention (or differences in means) values of the leucine and the respective control groups. Data analysis was performed using the Review Manager 5.2.4. software.
A total of 16 studies enrolling 999 subjects met the inclusion criteria. Compared with control groups, leucine supplementation significantly increased gain in body weight [mean differences 1.02 kg, 95%-CI (0.19, 1.85), p=0.02], lean body mass [mean differences 0.99 kg, 95%-CI (0.43, 1.55), p=0.0005], and body mass index [mean differences 0.33 kg/m2, 95%-CI (0.13, 0.53), p=0.001], when compared to the respective control groups. With respect to body weight and lean body mass, leucine supplementation turned out to be more effective in the subgroup of study participants with manifested sarcopenia. All other parameters under investigation were not affected by leucine supplementation in a fashion significantly different from controls.
It is concluded that leucine supplementation was found to exert beneficial effects on body weight, body mass index, and lean body mass in older persons in those subjects already prone to sarcopenia, but not muscle strength. However, due to the heterogeneity between the trials included in this systematic review, further studies adopting a homogenous design with respect to participant characteristics duration as well as the kind and amount of daily supplement in use are required.
本系统评价和荟萃分析的主要目的是综合现有的关于老年人补充亮氨酸的文献，以了解其对人体测量参数和肌肉力量的影响。次要目的是在可能的情况下进行选择性亚组分析，将健康和肌少症患者区分开来。
使用电子数据库 MEDLINE、EMBASE、SportDiscus 和 Cochrane 临床试验中央注册库进行文献检索，限制条件为随机对照试验或交叉设计的研究。考虑的参数包括体重、体重指数、瘦体重、体脂、体脂百分比、手握力和膝关节伸展力。此外，当可能时，还提取了葡萄糖代谢的生物标志物（空腹血糖、空腹胰岛素、白蛋白和 HOMA 指数）。对于每个感兴趣的结果测量，进行荟萃分析，以确定干预后亮氨酸和相应对照组之间的加权均数差值的干预效应。数据分析使用 Review Manager 5.2.4 软件进行。
共有 16 项研究纳入了 999 名受试者，符合纳入标准。与对照组相比，亮氨酸补充显著增加了体重增加[平均差异 1.02kg，95%CI（0.19，1.85），p=0.02]、瘦体重[平均差异 0.99kg，95%CI（0.43，1.55），p=0.0005]和体重指数[平均差异 0.33kg/m2，95%CI（0.13，0.53），p=0.001]，与相应的对照组相比。在体重和瘦体重方面，亮氨酸补充对已表现出肌少症的研究参与者亚组更为有效。在亮氨酸补充组和对照组之间，其他所有研究参数均无明显差异。
亮氨酸补充被发现对已经容易发生肌少症的老年人的体重、体重指数和瘦体重有有益的影响，但对肌肉力量没有影响。然而，由于本系统评价纳入的试验存在异质性，需要进一步采用具有参与者特征、持续时间以及每日补充剂种类和剂量均相同的同质设计的研究。
