scholarly journals Essential Amino Acids and Protein Synthesis: Insights into Maximizing the Muscle and Whole-Body Response to Feeding

Nutrients ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3717
Author(s):  
David D. Church ◽  
Katie R. Hirsch ◽  
Sanghee Park ◽  
Il-Young Kim ◽  
Jess A. Gwin ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Stepwise Regression ◽  
Muscle Protein ◽  
Area Under The Curve ◽  
Essential Amino Acids ◽  
Whole Body ◽  
Free Form ◽  
Body Protein ◽  
Fractional Synthetic Rate

Ingesting protein-containing supplements and foods provides essential amino acids (EAA) necessary to increase muscle and whole-body protein synthesis (WBPS). Large variations exist in the EAA composition of supplements and foods, ranging from free-form amino acids to whole protein foods. We sought to investigate how changes in peripheral EAA after ingesting various protein and free amino acid formats altered muscle and whole-body protein synthesis. Data were compiled from four previous studies that used primed, constant infusions of L-(ring-2H5)-phenylalanine and L-(3,3-2H2)-tyrosine to determine fractional synthetic rate of muscle protein (FSR), WBPS, and circulating EAA concentrations. Stepwise regression indicated that max EAA concentration (EAACmax; R2 = 0.524, p < 0.001), EAACmax (R2 = 0.341, p < 0.001), and change in EAA concentration (ΔEAA; R = 0.345, p < 0.001) were the strongest predictors for postprandial FSR, Δ (change from post absorptive to postprandial) FSR, and ΔWBPS, respectively. Within our dataset, the stepwise regression equation indicated that a 100% increase in peripheral EAA concentrations increases FSR by ~34%. Further, we observed significant (p < 0.05) positive (R = 0.420–0.724) correlations between the plasma EAA area under the curve above baseline, EAACmax, ΔEAA, and rate to EAACmax to postprandial FSR, ΔFSR, and ΔWBPS. Taken together our results indicate that across a large variety of EAA/protein-containing formats and food, large increases in peripheral EAA concentrations are required to drive a robust increase in muscle and whole-body protein synthesis.

scholarly journals Muscle Protein Synthesis and Whole-Body Protein Turnover Responses to Ingesting Essential Amino Acids, Intact Protein, and Protein-Containing Mixed Meals with Considerations for Energy Deficit

Nutrients ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 2457 ◽  
Author(s):  
Jess A. Gwin ◽  
David D. Church ◽  
Robert R. Wolfe ◽  
Arny A. Ferrando ◽  
Stefan M. Pasiakos
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Protein Turnover ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Energy Deficit ◽  
Whole Body ◽  
Intact Protein ◽  
Body Protein ◽  
Protein Feeding

Protein intake recommendations to optimally stimulate muscle protein synthesis (MPS) are derived from dose-response studies examining the stimulatory effects of isolated intact proteins (e.g., whey, egg) on MPS in healthy individuals during energy balance. Those recommendations may not be adequate during periods of physiological stress, specifically the catabolic stress induced by energy deficit. Providing supplemental intact protein (20–25 g whey protein, 0.25–0.3 g protein/kg per meal) during strenuous military operations that elicit severe energy deficit does not stimulate MPS-associated anabolic signaling or attenuate lean mass loss. This occurs likely because a greater proportion of the dietary amino acids consumed are targeted for energy-yielding pathways, whole-body protein synthesis, and other whole-body essential amino acid (EAA)-requiring processes than the proportion targeted for MPS. Protein feeding formats that provide sufficient energy to offset whole-body energy and protein-requiring demands during energy deficit and leverage EAA content, digestion, and absorption kinetics may optimize MPS under these conditions. Understanding the effects of protein feeding format-driven alterations in EAA availability and subsequent changes in MPS and whole-body protein turnover is required to design feeding strategies that mitigate the catabolic effects of energy deficit. In this manuscript, we review the effects, advantages, disadvantages, and knowledge gaps pertaining to supplemental free-form EAA, intact protein, and protein-containing mixed meal ingestion on MPS. We discuss the fundamental role of whole-body protein balance and highlight the importance of comprehensively assessing whole-body and muscle protein kinetics when evaluating the anabolic potential of varying protein feeding formats during energy deficit.

Meal stimulation of albumin synthesis: a significant contributor to whole body protein synthesis in humans

1992 ◽  
Vol 263 (4) ◽  
pp. E794-E799 ◽  
Author(s):  
P. De Feo ◽  
F. F. Horber ◽  
M. W. Haymond
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Combined Treatment ◽  
Essential Amino Acids ◽  
Whole Body ◽  
Albumin Synthesis ◽  
Body Protein ◽  
Peripheral Tissues ◽  
Stimulation Of

The present studies were performed to test the hypothesis that the liver, by increasing the synthesis of specific plasma proteins during the absorption of an amino acid meal, may play an important role in the temporary "storage" of ingested essential amino acids and to explore the effects of glucocorticosteroids and recombinant human growth hormone (rhGH) on these processes. The fractional synthetic rates of albumin and fibrinogen were determined using simultaneous infusions of intravenous [1-14C]leucine and intraduodenal [4,5-3H]leucine after 22 h fasting and during absorption of glucose and amino acids in four groups of normal subjects treated for 1 wk with placebo, prednisone (0.8 mg.kg-1.day-1), rhGH (0.1 mg.kg-1.day-1), or combined treatment. When compared with the fasted state and independent of the route of tracer delivery and hormonal treatment, albumin, but not fibrinogen, synthesis increased (P < 0.0001) during absorption of a mixed glucose amino acid meal in all groups. This increase in albumin synthesis accounted for 28% of the increase in whole body protein synthesis associated with feeding and for 24, 22, and 14% in the prednisone, rhGH, and combined treatment groups, respectively. These data suggest that the stimulation of albumin synthesis observed during feeding prevents irreversible oxidative losses of a significant fraction of ingested essential amino acids and may serve as a vehicle to capture excess dietary amino acids and transport them to peripheral tissues to sustain local protein synthesis.

scholarly journals Co-ingestion of leucine with protein does not further augment post-exercise muscle protein synthesis rates in elderly men

2008 ◽  
Vol 99 (3) ◽  
pp. 571-580 ◽  
Author(s):  
René Koopman ◽  
Lex B. Verdijk ◽  
Milou Beelen ◽  
Marchel Gorselink ◽  
Arie Nieuwenhuijzen Kruseman ◽  
...  
Keyword(s):  
Physical Activity ◽  
Protein Synthesis ◽  
Muscle Protein ◽  
Protein Hydrolysate ◽  
Muscle Protein Synthesis ◽  
Whole Body ◽  
Elderly Men ◽  
Body Protein ◽  
Synthetic Rate ◽  
Fractional Synthetic Rate

Leucine has been suggested to have the potential to modulate muscle protein metabolism by increasing muscle protein synthesis. The objective of this study was to investigate the surplus value of the co-ingestion of free leucine with protein hydrolysate and carbohydrate following physical activity in elderly men. Eight elderly men (mean age 73 ± 1 years) were randomly assigned to two cross-over treatments consuming either carbohydrate and protein hydrolysate (CHO+PRO) or carbohydrate, protein hydrolysate with additional leucine (CHO+PRO+leu) after performing 30 min of standardized physical activity. Primed, continuous infusions with l-[ring-13C6]phenylalanine and l-[ring-2H2]tyrosine were applied, and blood and muscle samples were collected to assess whole-body protein turnover as well as protein fractional synthetic rate in the vastus lateralis muscle over a 6 h period. Whole-body protein breakdown and synthesis rates were not different between treatments. Phenylalanine oxidation rates were significantly lower in the CHO+PRO+leu v. CHO+PRO treatment. As a result, whole-body protein balance was significantly greater in the CHO+PRO+leu compared to the CHO+PRO treatment (23·8 (sem 0·3) v. 23·2 (sem 0·3) μmol/kg per h, respectively; P < 0·05). Mixed muscle fractional synthetic rate averaged 0·081 (sem 0·003) and 0·082 (sem 0·006) %/h in the CHO+PRO+leu and CHO+PRO treatment, respectively (NS). 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.

scholarly journals Essential amino acid-enriched whey enhances post-exercise whole-body protein balance during energy deficit more than iso-nitrogenous whey or a mixed-macronutrient meal: a randomized, crossover study

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Jess A. Gwin ◽  
David D. Church ◽  
Adrienne Hatch-McChesney ◽  
Jillian T. Allen ◽  
Marques A. Wilson ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
G Protein ◽  
Essential Amino Acid ◽  
Muscle Protein ◽  
Energy Deficit ◽  
Whole Body ◽  
Free Form ◽  
Protein Balance ◽  
Body Protein

Abstract Background The effects of ingesting varying essential amino acid (EAA)/protein-containing food formats on protein kinetics during energy deficit are undetermined. Therefore, recommendations for EAA/protein food formats necessary to optimize both whole-body protein balance and muscle protein synthesis (MPS) during energy deficit are unknown. We measured protein kinetics after consuming iso-nitrogenous amounts of free-form essential amino acid-enriched whey (EAA + W; 34.7 g protein, 24 g EAA sourced from whey and free-form EAA), whey (WHEY; 34.7 g protein, 18.7 g EAA), or a mixed-macronutrient meal (MEAL; 34.7 g protein, 11.4 g EAA) after exercise during short-term energy deficit. Methods Ten adults (mean ± SD; 21 ± 4 y; 25.7 ± 1.7 kg/m2) completed a randomized, double-blind crossover study consisting of three, 5 d energy-deficit periods (− 30 ± 3% of total energy requirements), separated by 14 d. Whole-body protein synthesis (PS), breakdown (PB), and net balance (NET) were determined at rest and in response to combination exercise consisting of load carriage treadmill walking, deadlifts, and box step-ups at the end of each energy deficit using L-[2H5]-phenylalanine and L-[2H2]-tyrosine infusions. Treatments were ingested immediately post-exercise. Mixed-muscle protein synthesis (mixed-MPS) was measured during exercise through recovery. Results Change (Δ postabsorptive + exercise to postprandial + recovery [mean treatment difference (95%CI)]) in whole-body (g/180 min) PS was 15.8 (9.8, 21.9; P = 0.001) and 19.4 (14.8, 24.0; P = 0.001) greater for EAA + W than WHEY and MEAL, respectively, with no difference between WHEY and MEAL. ΔPB was − 6.3 (− 11.5, − 1.18; P = 0.02) greater for EAA + W than WHEY and − 7.7 (− 11.9, − 3.6; P = 0.002) greater for MEAL than WHEY, with no difference between EAA + W and MEAL. ΔNET was 22.1 (20.5, 23.8; P = 0.001) and 18.0 (16.5, 19.5; P = 0.00) greater for EAA + W than WHEY and MEAL, respectively, while ΔNET was 4.2 (2.7, 5.6; P = 0.001) greater for MEAL than WHEY. Mixed-MPS did not differ between treatments. Conclusions While mixed-MPS was similar across treatments, combining free-form EAA with whey promotes greater whole-body net protein balance during energy deficit compared to iso-nitrogenous amounts of whey or a mixed-macronutrient meal. Trial registration ClinicalTrials.gov, Identifier no. NCT04004715. Retrospectively registered 28 June 2019, first enrollment 6 June 2019

scholarly journals Insulin does not stimulate muscle protein synthesis during increased plasma branched-chain amino acids alone but still decreases whole body proteolysis in humans

2016 ◽  
Vol 311 (4) ◽  
pp. E671-E677 ◽  
Author(s):  
Sarah Everman ◽  
Christian Meyer ◽  
Lee Tran ◽  
Nyssa Hoffman ◽  
Chad C. Carroll ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Insulin Infusion ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Essential Amino Acids ◽  
Branched Chain Amino Acids ◽  
Whole Body ◽  
Synthesis Rate ◽  
Branched Chain

Insulin stimulates muscle protein synthesis when the levels of total amino acids, or at least the essential amino acids, are at or above their postabsorptive concentrations. Among the essential amino acids, branched-chain amino acids (BCAA) have the primary role in stimulating muscle protein synthesis and are commonly sought alone to stimulate muscle protein synthesis in humans. Fourteen healthy young subjects were studied before and after insulin infusion to examine whether insulin stimulates muscle protein synthesis in relation to the availability of BCAA alone. One half of the subjects were studied in the presence of postabsorptive BCAA concentrations (control) and the other half in the presence of increased plasma BCAA (BCAA). Compared with that prior to the initiation of the insulin infusion, fractional synthesis rate of muscle protein (%/h) did not change ( P > 0.05) during insulin in either the control (0.04 ± 0.01 vs 0.05 ± 0.01) or the BCAA (0.05 ± 0.02 vs. 0.05 ± 0.01) experiments. Insulin decreased ( P < 0.01) whole body phenylalanine rate of appearance (μmol·kg−1·min−1), indicating suppression of muscle proteolysis, in both the control (1.02 ± 0.04 vs 0.76 ± 0.04) and the BCAA (0.89 ± 0.07 vs 0.61 ± 0.03) experiments, but the change was not different between the two experiments ( P > 0.05). In conclusion, insulin does not stimulate muscle protein synthesis in the presence of increased circulating levels of plasma BCAA alone. Insulin's suppressive effect on proteolysis is observed independently of the levels of circulating plasma BCAA.

scholarly journals Comprehensive assessment of post-prandial protein handling by the application of intrinsically labelled protein in vivo in human subjects

2021 ◽  
pp. 1-9
Author(s):  
Jorn Trommelen ◽  
Andrew M. Holwerda ◽  
Philippe J. M. Pinckaers ◽  
Luc J. C. van Loon
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Stable Isotope ◽  
Dietary Protein ◽  
Protein Metabolism ◽  
Muscle Protein ◽  
Human Subjects ◽  
Whole Body ◽  
Body Protein

All human tissues are in a constant state of remodelling, regulated by the balance between tissue protein synthesis and breakdown rates. It has been well-established that protein ingestion stimulates skeletal muscle and whole-body protein synthesis. Stable isotope-labelled amino acid methodologies are commonly applied to assess the various aspects of protein metabolism in vivo in human subjects. However, to achieve a more comprehensive assessment of post-prandial protein handling in vivo in human subjects, intravenous stable isotope-labelled amino acid infusions can be combined with the ingestion of intrinsically labelled protein and the collection of blood and muscle tissue samples. The combined application of ingesting intrinsically labelled protein with continuous intravenous stable isotope-labelled amino acid infusion allows the simultaneous assessment of protein digestion and amino acid absorption kinetics (e.g. release of dietary protein-derived amino acids into the circulation), whole-body protein metabolism (whole-body protein synthesis, breakdown and oxidation rates and net protein balance) and skeletal muscle metabolism (muscle protein fractional synthesis rates and dietary protein-derived amino acid incorporation into muscle protein). The purpose of this review is to provide an overview of the various aspects of post-prandial protein handling and metabolism with a focus on insights obtained from studies that have applied intrinsically labelled protein under a variety of conditions in different populations.

Measurement of protein turnover in the small intestine of lambs. 2. Effects of feed intake

1997 ◽  
Vol 128 (2) ◽  
pp. 233-246 ◽  
Author(s):  
S. A. NEUTZE ◽  
J. M. GOODEN ◽  
V. H. ODDY
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Small Intestine ◽  
Experimental Model ◽  
Feed Intake ◽  
Protein Turnover ◽  
Jugular Vein ◽  
Specific Radioactivity ◽  
Whole Body ◽  
Body Protein

This study used an experimental model, described in a companion paper, to examine the effects of feed intake on protein turnover in the small intestine of lambs. Ten male castrate lambs (∼ 10 months old) were offered, via continuous feeders, either 400 (n = 5) or 1200 (n = 5) g/day lucerne chaff, and mean experimental liveweights were 28 and 33 kg respectively. All lambs were prepared with catheters in the cranial mesenteric vein (CMV), femoral artery (FA), jugular vein and abomasum, and a blood flow probe around the CMV. Cr-EDTA (0·139 mg Cr/ml, ∼ 0·2 ml/min) was infused abomasally for 24 h and L-[2,6-3H]phenylalanine (Phe) (420±9·35 μCi into the abomasum) and L-[U-14C]phenylalanine (49·6±3·59 μCi into the jugular vein) were also infused during the last 8 h. Blood from the CMV and FA was sampled during the isotope infusions. At the end of infusions, lambs were killed and tissue (n = 4) and digesta (n = 2) samples removed from the small intestine (SI) of each animal. Transfers of labelled and unlabelled Phe were measured between SI tissue, its lumen and blood, enabling both fractional and absolute rates of protein synthesis and gain to be estimated.Total SI mass increased significantly with feed intake (P < 0·05), although not on a liveweight basis. Fractional rates of protein gain in the SI tended to increase (P = 0·12) with feed intake; these rates were −16·2 (±13·7) and 23·3 (±15·2) % per day in lambs offered 400 and 1200 g/day respectively. Mean protein synthesis and fractional synthesis rates (FSR), calculated from the mean retention of 14C and 3H in SI tissue, were both positively affected by feed intake (0·01 < P < 0·05). The choice of free Phe pool for estimating precursor specific radioactivity (SRA) for protein synthesis had a major effect on FSR. Assuming that tissue free Phe SRA represented precursor SRA, mean FSR were 81 (±15) and 145 (±24) % per day in lambs offered 400 and 1200 g/day respectively. Corresponding estimates for free Phe SRA in the FA and CMV were 28 (±2·9) and 42 (±3·5) % per day on 400 g/day, and 61 (±2·9) and 94 (±6·0) on 1200 g/day. The correct value for protein synthesis was therefore in doubt, although indirect evidence suggested that blood SRA (either FA or CMV) may be closest to true precursor SRA. This evidence included (i) comparison with flooding dose estimates of FSR, (ii) comparison of 3H[ratio ]14C Phe SRA in free Phe pools with this ratio in SI protein, and (iii) the proportion of SI energy use associated with protein synthesis.Using the experimental model, the proportion of small intestinal protein synthesis exported was estimated as 0·13–0·27 (depending on the choice of precursor) and was unaffected by feed intake. The contribution of the small intestine to whole body protein synthesis tended to be higher in lambs offered 1200 g/day (0·21) than in those offered 400 g/day (0·13). The data obtained in this study suggested a role for the small intestine in modulating amino acid supply with changes in feed intake. At high intake (1200 g/day), the small intestine increases in mass and CMV uptake of amino acids is less than absorption from the lumen, while at low intake (400 g/day), this organ loses mass and CMV uptake of amino acids exceeds that absorbed. The implications of these findings are discussed.

scholarly journals Presleep dietary protein-derived amino acids are incorporated in myofibrillar protein during postexercise overnight recovery

2018 ◽  
Vol 314 (5) ◽  
pp. E457-E467 ◽  
Author(s):  
Jorn Trommelen ◽  
Imre W. K. Kouw ◽  
Andrew M. Holwerda ◽  
Tim Snijders ◽  
Shona L. Halson ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Dietary Protein ◽  
Myofibrillar Protein ◽  
Whole Body ◽  
Body Protein ◽  
Protein Ingestion ◽  
Casein Protein ◽  
The Impact ◽  
Myofibrillar Protein Synthesis

The purpose of this study was to determine the impact of ingesting 30 g casein protein with and without 2 g free leucine before sleep on myofibrillar protein synthesis rates during postexercise overnight recovery. Thirty-six healthy young men performed a single bout of resistance-type exercise in the evening (1945) after a full day of dietary standardization. Thirty minutes before sleep (2330), subjects ingested 30 g intrinsically l-[1-13C]phenylalanine-labeled protein with (PRO+leu, n = 12) or without (PRO, n = 12) 2 g free leucine, or a noncaloric placebo (PLA, n = 12). Continuous intravenous l-[ ring-2H5]phenylalanine, l-[1-13C]leucine, and l-[ ring-2H2]tyrosine infusions were applied. Blood and muscle tissue samples were collected to assess whole body protein net balance, myofibrillar protein synthesis rates, and overnight incorporation of dietary protein-derived amino acids into myofibrillar protein. Protein ingestion before sleep improved overnight whole body protein net balance ( P < 0.001). Myofibrillar protein synthesis rates did not differ significantly between treatments as assessed by l-[ ring-2H5]phenylalanine (0.057 ± 0.002, 0.055 ± 0.002, and 0.055 ± 0.004%/h for PLA, PRO, and PRO+leu, respectively; means ± SE; P = 0.850) or l-[1-13C]leucine (0.080 ± 0.004, 0.073 ± 0.004, and 0.083 ± 0.006%/h, respectively; P = 0.328). Myofibrillar l-[1-13C]phenylalanine enrichments increased following protein ingestion but did not differ between the PRO and PRO+leu treatments. In conclusion, protein ingestion before sleep improves whole body protein net balance and provides amino acids that are incorporated into myofibrillar protein during sleep. However, the ingestion of 30 g casein protein with or without additional free leucine before sleep does not increase muscle protein synthesis rates during postexercise overnight recovery.

Effects of acute creatine monohydrate supplementation on leucine kinetics and mixed-muscle protein synthesis

2001 ◽  
Vol 91 (3) ◽  
pp. 1041-1047 ◽  
Author(s):  
G. Parise ◽  
S. Mihic ◽  
D. MacLennan ◽  
K. E. Yarasheski ◽  
M. A. Tarnopolsky
Keyword(s):  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Fat Free Mass ◽  
Whole Body ◽  
Synthetic Rate ◽  
Fractional Synthetic Rate ◽  
Before And After ◽  
Total Creatine ◽  
Plasma Leucine

Creatine monohydrate (CrM) supplementation during resistance exercise training results in a greater increase in strength and fat-free mass than placebo. Whether this is solely due to an increase in intracellular water or whether there may be alterations in protein turnover is not clear at this point. We examined the effects of CrM supplementation on indexes of protein metabolism in young healthy men ( n = 13) and women ( n = 14). Subjects were randomly allocated to CrM (20 g/day for 5 days followed by 5 g/day for 3–4 days) or placebo (glucose polymers) and tested before and after the supplementation period under rigorous dietary and exercise controls. Muscle phosphocreatine, creatine, and total creatine were measured before and after supplementation. A primed-continuous intravenous infusion of l-[1-13C]leucine and mass spectrometry were used to measure mixed-muscle protein fractional synthetic rate and indexes of whole body leucine metabolism (nonoxidative leucine disposal), leucine oxidation, and plasma leucine rate of appearance. CrM supplementation increased muscle total creatine (+13.1%, P < 0.05) with a trend toward an increase in phosphocreatine (+8.8%, P = 0.09). CrM supplementation did not increase muscle fractional synthetic rate but reduced leucine oxidation (−19.6%) and plasma leucine rate of appearance (−7.5%, P < 0.05) in men, but not in women. CrM did not increase total body mass or fat-free mass. We conclude that short-term CrM supplementation may have anticatabolic actions in some proteins (in men), but CrM does not increase whole body or mixed-muscle protein synthesis.

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