Leucine Increases Protein Synthesis

[KevJr88]

This is for everyone to read. Most of you guys are right in being "anti" BCAAs. BCAAs can be uneffective because they all compete for the same receptor in the muscle. However, Leucine on its own has been shown over and over to increase muscle protein synthesis.

Here are three of over 100,000 hits that came back when I searched in my universities journal database.


Leucine and Protein Synthesis, mTOR and beyond
by Vary, Thomasc
The Journal of nutrition, ISSN 0022-3166, 08/2009, Volume 139, Issue 8, pp. 1439 - 1444
The effects of amino acid intake on protein synthesis in the intact rat appear to be mediated almost entirely by a single amino acid: leucine. The effect of leucine on protein synthesis appears to be closely associated with eIF4G phosphorylation and its association with eIF4E, but whether eIF4G phosphorylation actually mediates the effects of leucine or is merely associated with these events has not been elucidated. Additional research is needed to determine whether leucine effects eIF4G phosphorylation, whether eIF4G phos‐phorylation is essential for the effect of leucine on protein synthesis, and whether mTOR (mammalian target of rapamycin) or another component of the mTOR complex is somehow involved in leucine‐specific signaling.

Leucine stimulates protein synthesis in skeletal muscle of neonatal pigs by enhancing mTORC1 activation
Full Text Online
by Suryawan, Agus; Jeyapalan, Asumthia S; Orellana, Renan A; Wilson, Fiona A; Nguyen, Hanh V; Davis, Teresa A
AJP - Endocrinology and Metabolism, ISSN 0193-1849, 10/2008, Endocrinology and metabolism, Volume 295, Issue 4, pp. E868 - E875

Abstract
United States Department of Agriculture/Agriculture Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas Submitted 25 March 2008 ; accepted in final form 31 July 2008 Skeletal muscle in the neonate grows at a rapid rate due in part to an enhanced sensitivity to the postprandial rise in amino acids, particularly leucine. To elucidate the molecular mechanism by which leucine stimulates protein synthesis in neonatal muscle, overnight-fasted 7-day-old piglets were treated with rapamycin [an inhibitor of mammalian target of rapamycin (mTOR) complex (mTORC)1] for 1 h and then infused with leucine for 1 h. Fractional rates of protein synthesis and activation of signaling components that lead to mRNA translation were determined in skeletal muscle. Rapamycin completely blocked leucine-induced muscle protein synthesis. Rapamycin markedly reduced raptor-mTOR association, an indicator of mTORC1 activation. Rapamycin blocked the leucine-induced phosphorylation of mTOR, S6 kinase 1 (S6K1), and eukaryotic initiation factor (eIF)4E-binding protein-1 (4E-BP1) and formation of the eIF4E·eIF4G complex and increased eIF4E·4E-BP1 complex abundance. Rapamycin had no effect on the association of mTOR with rictor, a crucial component for mTORC2 activation, or G protein β-subunit-like protein (GβL), a component of mTORC1 and mTORC2. Neither leucine nor rapamycin affected the phosphorylation of AMP-activated protein kinase (AMPK), PKB, or tuberous sclerosis complex (TSC)2, signaling components that reside upstream of mTOR. Eukaryotic elongation factor (eEF)2 phosphorylation was not affected by leucine or rapamycin, although current dogma indicates that eEF2 phosphorylation is mTOR dependent. Together, these in vivo data suggest that leucine stimulates muscle protein synthesis in neonates by enhancing mTORC1 activation and its downstream effectors. mRNA translation; eukaryotic initiation factor 4G; AMP-activated protein kinase; raptor; rictor Address for reprint requests and other correspondence: T. A. Davis, USDA/ARS Children's Nutrition Research Center, Baylor College of Medicine, 1100 Bates St., Houston, TX 77030 (e-mail: tdavis{at}bcm.tmc.edu )

Leucine supplementation chronically improves muscle protein synthesis in older adults consuming the RDA for protein

Abstract
Protein-energy supplementation is routinely employed to combat muscle loss. However, success is often compromised by increased satiety, poor palatability, high costs and low compliance. For 2-weeks we supplemented meals of older individuals with leucine (4 g/meal; 3 meals/day; days 2-14). Metabolic studies were performed prior to (Day 1) and following (Day 15) supplementation. Leucine was not provided on metabolic study days. Venous blood and vastus lateralis muscle biopsies were obtained during a primed constant infusion of L-[ring-(13)C(6)] phenylalanine. Mixed muscle fractional synthesis rate (FSR), body composition and markers of nutrient signaling (mTOR, 4E-BP1 and p70S6K1 phosphorylation) were measured before and after a low protein/carbohydrate simulated meal. The meal modestly increased FSR on Day 1 (postabsorptive: 0.063 ± 0.004 vs. postprandial: 0.075 ± 0.006%/h; p = 0.03), however, two weeks of leucine supplementation increased postabsorptive FSR (p = 0.004) and the response to the meal (p = 0.01) (postabsorptive: 0.074 ± 0.007 vs. postprandial: 0.10 ± 0.007%/h). Changes in FSR were mirrored by increased phosphorylation of mTOR, 4E-BP1 and p70S6K1 (p ≤ 0.1). No change in fat free mass was observed (p > 0.05). In older adults, leucine supplementation may improve muscle protein synthesis in response to lower protein meals.

[hvactech1]

yes leucine is the "more important" part of bcaas but iso and valine are still beneficial, i add bulk leucine to my aminos

[KevJr88]

yes leucine is the "more important" part of bcaas but iso and valine are still beneficial, i add bulk leucine to my aminos

Thats practically pointless. You're adding the most beneficial muscle building amino acid to a shake that has X amount of other amino acids in it. Several of them in competition for the same receptor. If you want the full effects of leucine it has to be taken solo on a relatively empty stomach.

[hvactech1]

to each is there own

[BetterThanLife]

No one would deny that leucine is essential, and that it's the most important BCAA for increasing protein synthesis and preventing catabolism. However, more leucine does not necessarily mean more muscle. Most people already consume plenty of leucine by eating protein each day. Also, the most relevant studies in support of supplementation use the BCAAs together, as opposed to leucine by itself: http://www.ncbi.nlm.nih.gov/pubmed/16424141, http://www.ncbi.nlm.nih.gov/pubmed/15173434, http://www.ncbi.nlm.nih.gov/pubmed/7810616

[_Smitty_]

Also, the most relevant studies in support of supplementation use the BCAAs together, as opposed to leucine by itself: http://www.ncbi.nlm.nih.gov/pubmed/16424141, http://www.ncbi.nlm.nih.gov/pubmed/15173434, http://www.ncbi.nlm.nih.gov/pubmed/7810616

http://www.ncbi.nlm.nih.gov/pubmed/18403916
http://www.ncbi.nlm.nih.gov/pubmed/18056791
http://www.ncbi.nlm.nih.gov/pubmed/16424142
http://www.ncbi.nlm.nih.gov/pubmed/21775557

[cjwav34]

Supplementation of a leucine by it self can lead to a depletion of iso-leucine and valine.

[Starkk]

Will ingestion of leucine by itself increase potato synthesis

[cjwav34]

Will ingestion of leucine by itself increase potato synthesis

Only when taken with grape juice.

[stevedm]

Thats practically pointless. You're adding the most beneficial muscle building amino acid to a shake that has X amount of other amino acids in it. Several of them in competition for the same receptor. If you want the full effects of leucine it has to be taken solo on a relatively empty stomach.

Why dont you tell us what "receptor" they are competing for. As far as i know the transport of leucine, isoL and methionine is not 100% elucidated. Likely some sodium dependent transepithelial mchanism that we dont fully understand.