Institute of Women's Health Science, Showa Women's University, Tokyo 154-8533, Japan.
Nutrients. 2024 Aug 8;16(16):2606. doi: 10.3390/nu16162606.
In frail older adults (mean age 85 years old), a 3-month supplementation with a low dose (6 g/day) of medium-chain triglycerides (MCTs; C8:0 and C10:0) given at a meal increased muscle mass and function, relative to supplementation with long-chain triglycerides (LCTs), but it decreased fat mass. The reduction in fat mass was partly due to increased postprandial energy expenditure by stimulation of the sympathetic nervous system (SNS). However, the extracellular signals to ameliorate sarcopenia are unclear. The following three potential extracellular signals to increase muscle mass and function after MCT supplementation are discussed: (1) Activating SNS-the hypothesis for this is based on evidence that a beta2-adrenergic receptor agonist acutely (1-24 h) markedly upregulates isoforms of peroxisomal proliferator-activated receptor gamma coactivator-1alpha (PGC-1alpha) mRNAs, promotes mitochondrial biogenesis, and chronically (~1 month) induces muscle hypertrophy. (2) An increased concentration of plasma acyl-ghrelin stimulates growth hormone secretion. (3) A nitrogen-sparing effect of ketone bodies, which fuel skeletal muscle, may promote muscle protein synthesis and prevent muscle protein breakdown. This review will help guide clinical trials of using MCTs to treat primary (age-related) sarcopenia.
在体弱的老年人（平均年龄 85 岁）中，与长链甘油三酯（LCT）相比，在餐时补充低剂量（6 克/天）的中链甘油三酯（MCT；C8:0 和 C10:0）可增加肌肉质量和功能，但会减少脂肪量。脂肪量的减少部分归因于交感神经系统（SNS）的刺激增加了餐后能量消耗。然而，改善肌肉减少症的细胞外信号尚不清楚。讨论了以下三种潜在的细胞外信号，以增加 MCT 补充后的肌肉质量和功能：（1）激活 SNS-这一假设基于以下证据：β2-肾上腺素能受体激动剂可在短时间内（1-24 小时）急性显著上调过氧化物酶体增殖物激活受体γ共激活因子-1α（PGC-1α）mRNA 的异构体，促进线粒体生物发生，并在慢性（约 1 个月）诱导肌肉肥大。（2）血浆酰基-饥饿素浓度的增加刺激生长激素的分泌。（3）酮体的氮保护作用，为骨骼肌提供燃料，可能促进肌肉蛋白质合成并防止肌肉蛋白质分解。这篇综述将有助于指导使用 MCT 治疗原发性（年龄相关）肌肉减少症的临床试验。
