Evans Malkanthi, Guthrie Najla, Pezzullo John, Sanli Toran, Fielding Roger A, Bellamine Aouatef
KGK Synergize, London, ON Canada N6A 5R8.
Georgetown University Medical Center, 34744, Washington, DC USA.
Nutr Metab (Lond). 2017 Jan 18;14:7. doi: 10.1186/s12986-016-0158-y. eCollection 2017.
Progressive decline in skeletal muscle mass and function are growing concerns in an aging population. Diet and physical activity are important for muscle maintenance but these requirements are not always met. This highlights the potential for nutritional supplementation. As a primary objective, we sought to assess the effect of a novel combination of L-Carnitine, creatine and leucine on muscle mass and performance in older subjects.
Forty-two healthy older adults aged 55-70 years were randomized to receive either a novel L-Carnitine (1500 mg), L-leucine (2000 mg), creatine (3000 mg), Vitamin D3 (10 μg) (L-Carnitine-combination) product ( = 14), L-Carnitine (1500 mg) ( = 14), or a placebo ( = 14) for eight weeks. We evaluated body mass by DXA, upper and lower strength by dynamometry, and walking distance by a 6-min walk test at baseline and after eight weeks of intervention. These measures, reflecting muscle mass, functional strength and mobility have been combined to generate a primary composite score. Quality of life, blood safety markers, and muscle biopsies for protein biomarker analysis were also conducted at baseline and the end of the study.
The primary composite outcome improved by 63.5 percentage points in the L-Carnitine-combination group vs. placebo ( = 0.013). However, this composite score did not change significantly in the L-Carnitine group ( 0.232), and decreased slightly in the placebo group ( 0.534). Participants supplemented with the L-Carnitine-combination showed a 1.0 kg increase in total lean muscle mass ( = 0.013), leg lean muscle mass (0.35 kg, 0.005), and a 1.0 kg increase in lower leg strength ( = 0.029) at week 8. In addition, these increases were significant when compared to the placebo group 0.034, 0.026, and 0.002, respectively). Total mTOR protein expression was increased in participants in the L-Carnitine-combination group at the end of the study compared to the baseline ( = 0.017). This increase was also significant when compared to the placebo ( 0.039), suggesting that the increase in muscle mass and strength was due to new protein synthesis and mTOR pathway activation.
The trial did reach its primary objective. L-Carnitine combined with creatine and L-leucine significantly improved the composite score which reflects muscle mass and strength, at the end of the study compared to placebo. The combination showed an increase in mTOR protein level, a driver for increased muscle mass which translated to an improvement in muscle strength. This new combination may provide a potential nutritional intervention to promote muscle growth and improved physical functioning in older adults.
骨骼肌质量和功能的逐渐下降在老龄化人口中日益受到关注。饮食和体育活动对肌肉维持很重要，但这些需求并非总能得到满足。这凸显了营养补充的潜力。作为主要目标，我们试图评估左旋肉碱、肌酸和亮氨酸的新型组合对老年受试者肌肉质量和表现的影响。
42名年龄在55至70岁之间的健康老年人被随机分为三组，分别接受一种新型左旋肉碱（1500毫克）、L-亮氨酸（2000毫克）、肌酸（3000毫克）、维生素D3（10微克）（左旋肉碱组合）产品（n = 14）、左旋肉碱（1500毫克）（n = 14）或安慰剂（n = 14），为期八周。我们在基线和干预八周后通过双能X线吸收法评估体重，通过测力计评估上肢和下肢力量，并通过6分钟步行试验评估步行距离。这些反映肌肉质量、功能力量和活动能力的指标被综合起来生成一个主要综合评分。在基线和研究结束时还进行了生活质量、血液安全指标以及用于蛋白质生物标志物分析的肌肉活检。
与安慰剂组相比，左旋肉碱组合组的主要综合结局改善了63.5个百分点（P = 0.013）。然而，左旋肉碱组的这个综合评分没有显著变化（P = 0.232），安慰剂组略有下降（P = 0.534）。补充左旋肉碱组合的参与者在第8周时总瘦肌肉质量增加了1.0千克（P = 0.013），腿部瘦肌肉质量增加了0.35千克（P = 0.005），小腿力量增加了1.0千克（P = 0.029）。此外，与安慰剂组相比，这些增加具有显著性（分别为P = 0.034、P = 0.026和P = 0.002）。与基线相比，左旋肉碱组合组参与者在研究结束时总mTOR蛋白表达增加（P = 0.017）。与安慰剂相比，这种增加也具有显著性（P = 0.039），表明肌肉质量和力量的增加是由于新的蛋白质合成和mTOR途径激活。
该试验达到了其主要目标。与安慰剂相比，在研究结束时，左旋肉碱与肌酸和L-亮氨酸的组合显著改善了反映肌肉质量和力量的综合评分。该组合显示mTOR蛋白水平升高，这是肌肉质量增加的驱动因素，进而转化为肌肉力量的改善。这种新组合可能为促进老年人肌肉生长和改善身体功能提供一种潜在的营养干预措施。
