在健康老年人中，与食用类似乳制品的产品相比，食用富含亮氨酸的高蛋白乳清补充剂后，餐后肌肉蛋白质合成更高：一项随机对照试验。
Postprandial muscle protein synthesis is higher after a high whey protein, leucine-enriched supplement than after a dairy-like product in healthy older people: a randomized controlled trial.
作者信息
Luiking Yvette C, Deutz Nicolaas E P, Memelink Robert G, Verlaan Sjors, Wolfe Robert R
机构信息
Center for Translational Research in Aging and Longevity, Donald W, Reynolds Institute on Aging, University of Arkansas for Medical Sciences, 4301 W, Markham St, Slot 806, Little Rock AR 72205, USA.
出版信息
Nutr J. 2014 Jan 22;13:9. doi: 10.1186/1475-2891-13-9.
BACKGROUND
Decreased ability of muscles to respond to anabolic stimuli is part of the underlying mechanism for muscle loss with aging. Previous studies suggest that substantial amounts of essential amino acids (EAA), whey protein and leucine are beneficial for stimulation of acute muscle protein synthesis in older adults. However, these studies supplied only proteins, and no bolus studies have been done with dairy products or supplements that contained also fat and carbohydrates besides proteins. The aim of this study was to evaluate whether a specifically designed nutritional supplement in older adults stimulates muscle protein synthesis acutely to a greater extent than a conventional dairy product. Moreover, the combined effect with resistance exercise was studied by using a unilateral resistance exercise protocol.
METHODS
Utilizing a randomized, controlled, double blind study design, healthy older adults received a single bolus of a high whey protein, leucine-enriched supplement (EXP: 20 g whey protein, 3g total leucine, 150 kcal; n = 9) or an iso-caloric milk protein control (
CONTROL
6g milk protein; n = 10), immediately after unilateral resistance exercise. Postprandial mixed muscle protein fractional synthesis rate (FSR) was measured over 4h using a tracer infusion protocol with L-[ring-¹³C₆]-phenylalanine and regular blood and muscle sampling.
RESULTS
FSR was significantly higher overall after EXP (0.0780 ± 0.0070%/h) vs CONTROL (0.0574 ± 0.0066%/h (EMM ± SE)) (p = 0.049). No interaction between treatment and exercise was observed (p = 0.519). Higher postprandial concentrations of EAA and leucine are possible mediating factors for the FSR response, while plasma insulin increase did not dictate the FSR response. Moreover, when the protein intake from the supplements was expressed per kg leg lean mass (LLM), a significant correlation was observed with resting postprandial FSR (r = 0.48, P = 0.038).
CONCLUSIONS
Ingestion of a high whey protein, leucine-enriched supplement resulted in a larger overall postprandial muscle protein synthesis rate in healthy older subjects compared with a conventional dairy product. This acute effect is promising for long-term effects on parameters of muscle mass, strength and function in sarcopenic older people, which requires further study.
TRIAL REGISTRATION
This trial is registered in the Dutch Trial Register under number NTR1823.
背景
肌肉对合成代谢刺激的反应能力下降是衰老导致肌肉流失的潜在机制之一。先前的研究表明，大量必需氨基酸（EAA）、乳清蛋白和亮氨酸有利于刺激老年人的急性肌肉蛋白质合成。然而，这些研究仅提供了蛋白质，尚未对除蛋白质外还含有脂肪和碳水化合物的乳制品或补充剂进行单次大剂量研究。本研究的目的是评估一种专门设计的营养补充剂对老年人肌肉蛋白质合成的急性刺激作用是否比传统乳制品更大。此外，通过单侧抗阻运动方案研究了其与抗阻运动的联合效果。
方法
采用随机、对照、双盲研究设计，健康老年人在单侧抗阻运动后立即接受一次大剂量的高乳清蛋白、富含亮氨酸的补充剂（实验组：20g乳清蛋白、3g总亮氨酸、150kcal；n = 9）或等热量的乳蛋白对照物（对照组：6g乳蛋白；n = 10）。使用含有L-[环-¹³C₆]-苯丙氨酸的示踪剂输注方案以及定期的血液和肌肉采样，在4小时内测量餐后混合肌肉蛋白质分数合成率（FSR）。
结果
与对照组（0.0574±0.0066%/小时（EMM±SE））相比，实验组（0.0780±0.0070%/小时）的FSR总体上显著更高（p = 0.049）。未观察到治疗与运动之间的相互作用（p = 0.519）。餐后较高的EAA和亮氨酸浓度可能是FSR反应的介导因素，而血浆胰岛素升高并未决定FSR反应。此外，当以每千克腿部瘦体重（LLM）表示补充剂中的蛋白质摄入量时，观察到与静息餐后FSR存在显著相关性（r = 0.48，P = 0.038）。
结论
与传统乳制品相比，摄入高乳清蛋白、富含亮氨酸的补充剂可使健康老年人餐后总体肌肉蛋白质合成率更高。这种急性效应有望对肌肉减少症老年人的肌肉质量、力量和功能参数产生长期影响，这需要进一步研究。
试验注册
本试验已在荷兰试验注册中心注册，注册号为NTR1823。
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