A high proportion of leucine is required for optimal stimulation of the rate of muscle protein synthesis by essential amino acids in the elderly.

@article{Katsanos2006AHP,
  title={A high proportion of leucine is required for optimal stimulation of the rate of muscle protein synthesis by essential amino acids in the elderly.},
  author={Christos S Katsanos and Hisamine Kobayashi and Melinda Sheffield-Moore and Asle A Aarsland and Robert R. Wolfe},
  journal={American journal of physiology. Endocrinology and metabolism},
  year={2006},
  volume={291 2},
  pages={
          E381-7
        }
}
This study was designed to evaluate the effects of enriching an essential amino acid (EAA) mixture with leucine on muscle protein metabolism in elderly and young individuals. [...] Key Method Four (2 elderly and 2 young) groups were studied before and after ingestion of 6.7 g of EAAs. EAAs were based on the composition of whey protein [26% leucine (26% Leu)] or were enriched in leucine [41% leucine (41% Leu)].Expand
Leucine supplementation improves muscle protein synthesis in elderly men independently of hyperaminoacidaemia
TLDR
It is concluded that leucine supplementation during feeding improves muscle protein synthesis in the elderly independently of an overall increase of other amino acids. Expand
Co-ingestion of leucine with protein does not further augment post-exercise muscle protein synthesis rates in elderly men.
TLDR
Co-ingestion of leucine with carbohydrate and protein following physical activity does not further elevate muscle protein fractional synthetic rate in elderly men when ample protein is ingested. Expand
Differential effects of leucine and leucine-enriched whey protein on skeletal muscle protein synthesis in aged mice.
TLDR
Administration of other amino acids may be required for leucine administration to stimulate muscle protein synthesis in aged mice, as suggested in this study. Expand
Effect of a leucine-enriched essential amino acids mixture on muscle recovery
TLDR
LEAA consumption suppressed exercise-induced elevation of muscle damage markers in blood, which suggests that LEAA could attenuate muscle damage and aid muscle recovery. Expand
Absence of leucine in an essential amino acid supplement reduces activation of mTORC1 signalling following resistance exercise in young females.
TLDR
The presence of leucine in the supplement enhances the stimulatory effect on mTORC1 signalling and reduces the level of tyrosine and the sum of the EAA in muscle and plasma, suggesting a stimulation of protein synthesis and (or) inhibition of breakdown, leading to improvement in net protein balance. Expand
Co-ingestion of leucine with protein does not further augment post-exercise muscle protein synthesis rates in elderly men
TLDR
Co-ingestion of leucine with carbohydrate and protein following physical activity does not further elevate muscle protein fractional synthetic rate in elderly men when ample protein is ingested. Expand
Effects of leucine-enriched essential amino acid and whey protein bolus dosing upon skeletal muscle protein synthesis at rest and after exercise in older women
TLDR
LEAA_1.5, despite only providing 0.6 g of leucine, robustly stimulated MPS, with negligible trophic advantage of greater doses of LEAA or even to 40 g WP, highlighting that composition of EAA is most crucial for anabolism. Expand
Muscle protein synthesis and balance responsiveness to essential amino acids ingestion in the presence of elevated plasma free fatty acid concentrations.
TLDR
Elevated plasma FFA concentrations do not interfere with the response of muscle protein synthesis and balance to a bolus ingestion of EAAs and are associated with impaired glucose disposal in skeletal muscle. Expand
Safety and Tolerability of Leucine Supplementation in Elderly Men.
TLDR
2 current studies to determine the Tolerable Upper Intake Level (UL) for leucine in young and elderly men are described and the conceptual model of determining the maximum oxidative capacity of an amino acid to be an ideal marker for identifying the UL is tested. Expand
Leucine, Not Total Protein, Content of a Supplement Is the Primary Determinant of Muscle Protein Anabolic Responses in Healthy Older Women.
TLDR
Lower-protein supplements with added leucine may represent an advantageous approach in older adults to maintain skeletal muscle anabolic sensitivity and attenuate muscle loss; however, further work is needed using longer-term interventions to substantiate these findings. Expand
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