Plasma Essential Amino Acid Concentrations Research Articles

440 Muscle Protein Synthesis and Whole-Body Protein Balance Following Ingestion of Beef or a Soy Protein Based Meat Alternative

OBJECTIVES/GOALS: We endeavor to investigated the hypothesis that muscle protein synthesis (MPS) is stimulated more after consumption of a 4-ounce beef patty as compared to 4- and 8-ounces of a soy protein based meat alternative (SPBMA) and if a greater stimulation is related to differences in the responses of plasma essential amino acid (EAA) concentrations. METHODS/STUDY POPULATION: Participants were aged 18 to 40 years of age with a BMI between 20 and 32 kg/m2. Written informed consent was obtained from all participants, and approved by UAMS IRB. Participants were assigned to one of three intervention groups via a single-blinded permuted block randomization, stratified for sex: 4 oz beef patty; 4 oz SPBMA; 2 x 4 oz (8oz) SPBMA. The impossible burgerTM was selected as it is primarily soy protein, a high-quality plant protein, and specifically designed to mimic a beef burger. Stable isotope were infused to assess protein metabolism. Appropriate muscle and blood samples were obtained. Enrichment and plasma EAA concentrations were measured with mass spectrometry. ANOVA’s on the change from basal to postprandial were used to identify group difference, significance was accepted at p < 0.05. RESULTS/ANTICIPATED RESULTS: The MPS increase from basal to postprandial indicated a significant main effect of group (p = 0.026), with the beef group (0.020 ± 0.016%/hour) being significantly greater than the 4oz SPBMA (0.003 ± 0.010%/hour; p = 0.021) but not the 8oz PBMA group (0.013 ± 0.016%/hour; p = 0.454). Similar results were observed for whole-body protein synthesis, where the beef group (p = 0.042) and 8oz SPBMA (p = 0.033) were significantly greater than the 4oz SPBMA (p = 0.021). Whole-body protein balance was significantly greater in the 8oz SPBMA as compared to 4oz of beef and SPBMA. Lastly, we observed a significantly relationship (p = 0.046; r = 0.411) between the maximal plasma EAA concentration and change in MPS, indicating the greater rate of MPS following 4oz of beef is mediated by an higher increase in plasma EAA concentrations. DISCUSSION/SIGNIFICANCE: In conclusion, 4oz of beef stimulates muscle protein FSR more than 4oz of a SPBMA. A common SPBMA can stimulate increase in protein metabolism, however, greater amounts are required as compared to beef protein. Further, the change in the muscle protein FSR response was significantly correlated with the maximal EAA concentration.

Post-prandial muscle protein synthesis rates following the ingestion of pea-derived protein do not differ from ingesting an equivalent amount of milk-derived protein in healthy, young males.

Plant-derived proteins have received considerable attention as an alternative to animal-derived proteins. However, plant-derived proteins are considered to have less anabolic properties when compared with animal-derived proteins. The lower muscle protein synthesis rates following ingestion of plant- compared with animal-derived protein have been attributed to the lower essential amino acid content of plant-derived proteins and/or their specific amino acid deficiencies. This study aimed to compare post-prandial muscle protein synthesis rates following the ingestion of 30g pea-derived protein with 30g milk-derived protein in healthy, young males. In a randomized, double-blind, parallel-group design, 24 young males (24 ± 3 y) received a primed continuous L-[ring-13C6]-phenylalanine infusion after which they ingested 30g pea (PEA) or 30g milk-derived protein (MILK). Blood and muscle biopsies were collected frequently for 5h to assess post-prandial plasma amino acid profiles and subsequent post-prandial muscle protein synthesis rates. MILK increased plasma essential amino acid concentrations more than PEA over the 5h post-prandial period (incremental area under curve 151 ± 31 vs 102 ± 15mmol∙300min∙L-1, respectively; P < 0.001). Ingestion of both MILK and PEA showed a robust muscle protein synthetic response with no significant differences between treatments (0.053 ± 0.013 and 0.053 ± 0.017%∙h-1, respectively; P = 0.96). Post-prandial muscle protein synthesis rates following the ingestion of 30g pea-derived protein do not differ from the response following ingestion of an equivalent amount of milk-derived protein. International Clinical Trials Registry Platform (NTR6548; 27-06-2017).

Higher Muscle Protein Synthesis Rates Following Ingestion of an Omnivorous Meal Compared with an Isocaloric and Isonitrogenous Vegan Meal in Healthy, Older Adults

BackgroundPlant-derived proteins are considered to have fewer anabolic properties when compared with animal-derived proteins. The anabolic properties of isolated proteins do not necessarily reflect the anabolic response to the ingestion of whole foods. The presence or absence of the various components that constitute the whole-food matrix can strongly impact protein digestion and amino acid absorption and, as such, modulate postprandial muscle protein synthesis rates. So far, no study has compared the anabolic response following ingestion of an omnivorous compared with a vegan meal. ObjectivesThis study aimed to compare postprandial muscle protein synthesis rates following ingestion of a whole-food meal providing 100 g lean ground beef with an isonitrogenous, isocaloric whole-food plant-based meal in healthy, older adults. MethodsIn a randomized, counter-balanced, cross-over design, 16 older (65–85 y) adults (8 males, 8 females) underwent 2 test days. On one day, participants consumed a whole-food omnivorous meal containing beef as the primary source of protein (0.45 g protein/kg body mass; MEAT). On the other day, participants consumed an isonitrogenous and isocaloric whole-food vegan meal containing unprocessed plant-based whole foods (PLANT). Primed continuous L-[ring-13C6]-phenylalanine infusions were applied with blood and muscle biopsies being collected frequently for 6 h to assess postprandial plasma amino acid profiles and muscle protein synthesis rates. Data are presented as means ± standard deviations and were analyzed by 2 way-repeated measures analysis of variance and paired-samples t tests. ResultsMEAT increased plasma essential amino acid concentrations more than PLANT over the 6-h postprandial period (incremental area under curve 87 ± 37 compared with 38 ± 54 mmol·6 h/L, respectively; P-interaction < 0.01). Ingestion of MEAT resulted in ∼47% higher postprandial muscle protein synthesis rates when compared with the ingestion of PLANT (0.052 ± 0.023 and 0.035 ± 0.021 %/h, respectively; paired-samples t test: P = 0.037). ConclusionsIngestion of a whole-food meal containing beef results in greater postprandial muscle protein synthesis rates when compared with the ingestion of an isonitrogenous whole-food plant-based meal in older adults.This study was registered at clinicaltrials.gov as NCT05151887.

Ingestion of mycoprotein, pea protein, and their blend support comparable postexercise myofibrillar protein synthesis rates in resistance-trained individuals.

Pea protein is an attractive nonanimal-derived protein source to support dietary protein requirements. However, although high in leucine, a low methionine content has been suggested to limit its anabolic potential. Mycoprotein has a complete amino acid profile which, at least in part, may explain its ability to robustly stimulate myofibrillar protein synthesis (MyoPS) rates. We hypothesized that an inferior postexercise MyoPS response would be seen following ingestion of pea protein compared with mycoprotein, which would be (partially) rescued by blending the two sources. Thirty-three healthy, young [age: 21 ± 1 yr, body mass index (BMI): 24 ± 1 kg·m-2] and resistance-trained participants received primed, continuous infusions of l-[ring-2H5]phenylalanine and completed a bout of whole body resistance exercise before ingesting 25 g of protein from mycoprotein (MYC, n = 11), pea protein (PEA, n = 11), or a blend (39% MYC, 61% PEA) of the two (BLEND, n = 11). Blood and muscle samples were taken pre-, 2 h, and 4 h postexercise/protein ingestion to assess postabsorptive and postprandial postexercise myofibrillar protein fractional synthetic rates (FSRs). Protein ingestion increased plasma essential amino acid and leucine concentrations (time effect; P < 0.0001), but more rapidly in BLEND and PEA compared with MYC (time × condition interaction; P < 0.0001). From similar postabsorptive values (MYC, 0.026 ± 0.008%·h-1; PEA, 0.028 ± 0.007%·h-1; BLEND, 0.026 ± 0.006%·h-1), resistance exercise and protein ingestion increased myofibrillar FSRs (time effect; P < 0.0001) over a 4-h postprandial period (MYC, 0.076 ± 0.004%·h-1; PEA, 0.087 ± 0.01%·h-1; BLEND, 0.085 ± 0.01%·h-1), with no differences between groups (all; P > 0.05). These data show that all three nonanimal-derived protein sources have utility in supporting postexercise muscle reconditioning.NEW & NOTEWORTHY This study provides evidence that pea protein (PEA), mycoprotein (MYC), and their blend (BLEND) can support postexercise myofibrillar protein synthesis rates following a bout of whole body resistance exercise. Furthermore, these data suggest that a methionine deficiency in pea may not limit its capacity to stimulate an acute increase in muscle protein synthesis (MPS).

The Muscle Protein Synthetic Response to the Ingestion of a Plant-Derived Protein Blend Does Not Differ from an Equivalent Amount of Milk Protein in Healthy Young Males

Plant-derived proteins are considered to have lesser anabolic properties when compared with animal-derived proteins. The attenuated rise in muscle protein synthesis rates following ingestion of plant-derived compared with animal-derived protein has been, at least partly, attributed to deficiencies in specific amino acids such as leucine, lysine, and/or methionine. Combining different plant-derived proteins could provide plant-derived protein blends with a more balanced amino acid profile. This study aimed to compare postprandial muscle protein synthesis rates following the ingestion of 30 g milk protein with a 30 g blend combining wheat, corn, and pea protein in healthy young men. In a randomized, double-blind, parallel-group design, 24 young males (aged 24 ± 4 y) received a primed continuous l-[ring-13C6]-phenylalanine infusion after which they ingested 30 g milk protein (MILK) or a 30 g plant-derived protein blend combining 15 g wheat, 7.5 g corn, and 7.5 g pea protein (PLANT-BLEND). Blood and muscle biopsies were collected frequently for 5 h to assess postprandial plasma amino acid profiles (secondary outcome) and subsequent muscle protein synthesis rates (primary outcome). Data were analyzed by 2-factor repeated measures ANOVA and 2-samples t tests. MILK increased plasma essential amino acid concentrations more than PLANT-BLEND over the 5 h postprandial period (incremental AUC = 151 ± 31 compared with 79 ± 12 mmol·300 min·L-1, respectively; P < 0.001). Ingestion of both MILK and PLANT-BLEND increased myofibrillar protein synthesis rates (P < 0.001), with no significant differences between treatments (0.053 ± 0.013%/h and 0.064 ± 0.016%/h, respectively; P = 0.08). Ingestion of 30 g plant-derived protein blend combining wheat-, corn-, and pea-derived protein increases muscle protein synthesis rates in healthy young males. The muscle protein synthetic response to the ingestion of 30 g of this plant-derived protein blend does not differ from the ingestion of an equivalent amount of a high-quality animal-derived protein. Clinical trial registry number for Nederlands Trial Register: NTR6548 (https://trialsearch.who.int/Trial2.aspx?TrialID=NTR6548).

Raw Eggs To Support Postexercise Recovery in Healthy Young Men: Did Rocky Get It Right or Wrong?

Egg protein is ingested during recovery from exercise to facilitate the postexercise increase in muscle protein synthesis rates and, as such, to support the skeletal muscle adaptive response to exercise training. The impact of cooking egg protein on postexercise muscle protein synthesis is unknown. We sought to compare the impact of ingesting unboiled (raw) compared with boiled eggs during postexercise recovery on postprandial myofibrillar protein synthesis rates. In a parallel design, 45 healthy, resistance-trained young men (age: 24 y; 95% CI: 23, 25 y) were randomly assigned to ingest 5 raw eggs (∼30 g protein), 5 boiled eggs (∼30 g protein), or a control breakfast (∼5 g protein) during recovery from a single session of whole-body resistance-type exercise. Primed continuous l-[ring-13C6]-phenylalanine infusions were applied, with frequent blood sampling. Muscle biopsies were collected immediately after cessation of resistance exercise and at 2 and 5 h into the postexercise recovery period. Primary (myofibrillar protein synthesis rates) and secondary (plasma amino acid concentrations) outcomes were analyzed using repeated-measures (time × group) ANOVA. Ingestion of eggs significantly increased plasma essential amino acid (EAA) concentrations, with 20% higher peak concentrations following ingestion of boiled compared with raw eggs (time × group: P < 0.001). Myofibrillar protein synthesis rates were significantly increased during the postexercise period when compared with basal, postabsorptive values in all groups (2-4-fold increase: P < 0.001). Postprandial myofibrillar protein synthesis rates were 20% higher after ingesting raw eggs [0.067%/h; 95% CI: 0.056, 0.077%/h; effect size (Cohen d): 0.63], and 18% higher after ingesting boiled eggs (0.065%/h; 95% CI: 0.058, 0.073%/h; effect size: 0.69) when compared with the control breakfast (0.056%/h; 95% CI: 0.048, 0.063%/h), with no significant differences between groups (time × group: P = 0.077). The ingestion of raw, as opposed to boiled, eggs attenuates the postprandial rise in circulating EAA concentrations. However, postexercise muscle protein synthesis rates do not differ after ingestion of 5 raw compared with 5 boiled eggs in healthy young men. This trial was registered at the Nederlands Trial Register as NL6506 (www.trialregister.nl).

Mycoprotein ingestion within or without its wholefood matrix results in equivalent stimulation of myofibrillar protein synthesis rates in resting and exercised muscle of young men.

Ingestion of mycoprotein stimulates skeletal muscle protein synthesis (MPS) rates to a greater extent than concentrated milk protein when matched for leucine content, potentially attributable to the wholefood nature of mycoprotein. We hypothesised that bolus ingestion of mycoprotein as part of its wholefood matrix would stimulate MPS rates to a greater extent compared with a leucine-matched bolus of protein concentrated from mycoprotein. Twenty-four healthy young (age, 21 ± 2 years; BMI, 24 ± 3 kg.m2) males received primed, continuous infusions of L-[ring-2H5]phenylalanine and completed a bout of unilateral resistance leg exercise before ingesting either 70 g mycoprotein (MYC; 31·4 g protein, 2·5 g leucine; n 12) or 38·2 g of a protein concentrate obtained from mycoprotein (PCM; 28·0 g protein, 2·5 g leucine; n 12). Blood and muscle samples (vastus lateralis) were taken pre- and (4 h) post-exercise/protein ingestion to assess postabsorptive and postprandial myofibrillar protein fractional synthetic rates (FSR) in resting and exercised muscle. Protein ingestion increased plasma essential amino acid and leucine concentrations (P < 0·0001), but more rapidly (both 60 v. 90 min; P < 0·0001) and to greater magnitudes (1367 v. 1346 μmol·l-1 and 298 v. 283 μmol·l-1, respectively; P < 0·0001) in PCM compared with MYC. Protein ingestion increased myofibrillar FSR (P < 0·0001) in both rested (MYC, Δ0·031 ± 0·007 %·h-1 and PCM, Δ0·020 ± 0·008 %·h-1) and exercised (MYC, Δ0·057 ± 0·011 %·h-1 and PCM, Δ0·058 ± 0·012 %·h-1) muscle, with no differences between conditions (P > 0·05). Mycoprotein ingestion results in equivalent postprandial stimulation of resting and post-exercise myofibrillar protein synthesis rates irrespective of whether it is consumed within or without its wholefood matrix.

Whey protein concentrate mixed beverages and plasma amino acid response in young males

Whey protein isolate (WPI) and whey protein hydrolysate (WPH) contains more protein than whey protein concentrate. However, to achieve a better taste, most commercial products mix WPI and WPH with whey protein concentrate (WPC). This study aimed to compare postprandial blood amino acids following ingestion of three beverages: WPImixed with WPC (WPI-mixed), WPH-mixed with WPI (WPH-mixed), and placebo. A total of ten healthy men aged between 18 and 30, who regularly engaged in exercise training, were recruited as participants. They each received 350 mL of each beverage on separate days and 6-day apart. Concentrations of plasma essential amino acids (EAA), branched-chain amino acids (BCAA), and leucine (Leu) were measured in blood samples taken from participants every 15 mins for 2 hrs. Plasma concentrations of EAA, BCAA, and Leu increased after ingestion of the WPI-mixed and WPH-mixed beverages versus the placebo beverage (P&lt;0.05). Plasma EAA did not differ between WPI- mixed and WPmixed trials. In contrast, plasma concentrations of BCAA after WPI-mixed were higher than after WPH-mixed at 30 mins. The same was observed for Leu at 30 and 75 mins after ingestion. The higher plasma BCAA and Leu in the WPI-mixed trial versus the WPHmixed trial may have been due to the presence of short-chain peptides, as bioactive peptides, in WPH-mixed, which were absorbed. In conclusion, there was no difference in plasma EAA, but plasma concentrations of leucine and BCAA were higher in the WPImixed trial than WPH-mixed trial. Therefore, future research should investigate bioactive peptides along with plasma amino acids.

Nitrogen Balance after the Administration of a Prolonged-Release Protein Substitute for Phenylketonuria as a Single Dose in Healthy Volunteers.

Nitrogen balance is the difference between nitrogen excreted as urea and nitrogen ingested, mainly in proteins. Increased circulating concentrations of amino acids (AA) in the bloodstream are usually associated with proportional increases in the production and excretion of urea. Previously, we reported results from a randomized, controlled, single-dose, crossover trial in healthy adult volunteers (n = 30) (Trial Registration: ISRCTN11016729), in which a Test product (prolonged-release AA mixture formulated with Physiomimic Technology™ (PT™)) significantly slowed down the release and reduced the peak plasma concentrations of essential AAs compared with a free AA mixture (Reference product) while maintaining essential AA bioavailability. Here, we report an assessment of the nitrogen balance from the same study. The amount of nitrogen contained in plasma AAs, levels of blood urea nitrogen (BUN) (p < 0.0001) and changes in BUN (p < 0.0001) were smaller after the Test product compared with the Reference product. These findings suggest that the production of urea in proportion to systemic AA availability was significantly smaller after the administration of the Test product compared with the Reference product and that the test product conferred the increased utilization of AAs for protein synthesis and reduced their oxidation and conversion to urea. In the clinical setting, it is possible that the effects of PT™ observed on the disposition of free AAs in this study may translate to health benefits in terms of physiological body composition and growth if used for the treatment of subjects with phenylketonuria (PKU). Further investigation in patients with PKU is warranted.

The Muscle Protein Synthetic Response to the Ingestion of a Plant-Based Protein Blend Is Not Different From Milk Protein in Healthy, Young Males

Abstract Objectives It has been reported that plant-based proteins are not as effective as animal-based proteins in their capacity to stimulate muscle protein synthesis rates. This has been attributed to the lower essential amino acid content and the selective deficiency in specific amino acids. It has been hypothesized that a blend of different plant-based proteins may complement each other and, as such, compensate for such deficits. This study compares post-prandial muscle protein synthesis rates following the ingestion of 30 g milk protein with the ingestion of a 30 g blend of wheat, corn, and pea protein in vivo, in healthy young males. Methods In a randomized, double blind, parallel-group design, 24 healthy young males (24 ± 4 y) received a primed continuous infusion of L-[ring-13C6]-phenylalanine and ingested 30 g milk protein (MILK), or a 30 g protein blend with 15 g wheat, 7.5 g corn, and 7.5 g pea protein (PLANT) in beverage form (n = 12 per group). Both interventional drinks were matched for leucine content. Blood and muscle biopsies were collected for 5 h following protein ingestion to assess post-prandial plasma amino acid profiles and myofibrillar protein synthesis rates. Data are expressed as mean ± SD. Results MILK increased plasma essential amino acid concentrations ∼2 fold more than PLANT over the 5 h post-prandial period (incremental area under curve (iAUC): 151 ± 31 vs 79 ± 12 mmol∙5 h∙L−1 respectively; P &amp;lt; 0.001). Similarly, the leucine iAUC was ∼16% greater for MILK vs PLANT (36 ± 7 vs 31 ± 4 mmol∙5 h∙L−1 respectively; P &amp;lt; 0.05). Ingestion of both MILK and PLANT increased myofibrillar protein synthesis rates when compared to basal post-absorptive values (P &amp;lt; 0.001), with no significant differences between treatments (0.053 ± 0.013 vs 0.064 ± 0.016%∙h−1, respectively; P &amp;gt; 0.05). Conclusions Ingestion of 30 g of a wheat, corn, and pea protein blend increases muscle protein synthesis rates in healthy, young males. The post-prandial muscle protein synthetic response to the ingestion of 30 g of a wheat, corn and pea protein blend does not differ from the ingestion of an equivalent amount of milk protein in healthy, young males. Funding Sources TiFN

Equivalent servings of free-range reindeer promote greater net protein balance compared to commercial beef

ABSTRACT Wild game consumption has been associated with health benefits but the acute influence on human protein metabolism remains unknown. We compared feeding-induced responses of equivalent amounts of free-range reindeer (FR) and commercial beef (CB) on protein kinetics using stable isotope methodology. Seven participants (age: 40 ± 14 years; body mass index: 24 ± 3 kg/m2) completed two randomised studies, ingesting 2 oz of FR or CB. L-[ring 2H5]phenylalanine & L-[ring 2H2]tyrosine were delivered via primed, continuous intravenous infusion. Blood samples were collected during the basal period and following consumption of FR or CB. Feeding-induced changes in whole-body protein synthesis (PS), protein breakdown (PB), and net protein balance (NB) were determined via plasma sample isotope enrichment analysis by gas chromatography-mass spectrometry; plasma essential amino acid (EAA) concentrations were determined by liquid chromatography-electrospray ionisation-mass spectrometry. Plasma post-prandial EAA concentrations were higher with FR compared to CB (P < 0.05). The acute feeding-induced PS response was not different, but PB was reduced and contributed to a superior level of NB (P < 0.00001) in FR compared to CB. Our results demonstrate that FR may influence more favourable protein metabolism than CB. These data support potential health benefits of wild game onf whole-body protein. Abbreviations: BMI: body mass index; DIAAS: digestible indispensable amino acid score; CB: commercial beef; EAA: essential amino acids; FR: free-range reindeer; Ra: rate of appearance; UAF: University of Alaska Fairbanks; USDA: USA Department of Agriculture

The impact of Hayward green kiwifruit on dietary protein digestion and protein metabolism

PurposeThe purpose of the study was to determine if an actinidin protease aids gastric digestion and the protein anabolic response to dietary protein.MethodsHayward green kiwifruit (containing an actinidin protease) and Hort 16A gold kiwifruit (devoid of actinidin protease) were given in conjunction with a beef meal to healthy older subjects. Twelve healthy older males (N = 6) and females (N = 6) were studied with a randomized, double-blinded, crossover design to assess muscle and whole-body protein metabolism before and after ingestion of kiwifruit and 100 g of ground beef. Subjects consumed 2 of each variety of kiwifruit daily for 14 d prior to each metabolic study, and again during each study with beef intake.ResultsHayward green kiwifruit consumption with beef resulted in a more rapid increase in peripheral plasma essential amino acid concentrations. There were significant time by kiwifruit intake interactions for plasma concentrations of EAAs, branched chain amino acids (BCAAs), and leucine (P < 0.01). However, there was no difference in the total amount of EAAs absorbed. As a result, there were no differences between kiwifruit in any of the measured parameters of protein kinetics.ConclusionConsumption of Hayward green kiwifruit, with a beef meal facilitates protein digestion and absorption of the constituent amino acids as compared to Hort 16A gold kiwifruit.Clinical trialNCT04356573, April 21, 2020 “retrospectively registered”.

Dietary supplementation with citrus extract alters the plasma parameters, circulating amino acid profiles and gene expression of small intestinal nutrient transporters in Chinese yellow-feathered broilers.

This study evaluated the effects of citrus extract (CE) on growth performance, plasma amino acid (AA) profiles, intestinal development and small intestine AA and peptide transporter expression levels in broilers. A total of 540 one-day-old yellow-feathered broilers were fed a basal diet without any antibiotic (control group), or a basal diet containing 10 mg kg-1 zinc bacitracin (antibiotic group), or a basal diet supplemented with 10 mg kg-1 CE (CE group). After 63 days of feeding, two broilers per pen were slaughtered to collect tissues for further analysis. Results showed that CE increased (P < 0.05) the final body weight and average daily gain from day 1 to 63, and decreased (P < 0.05) the feed/gain ratio from day 1 to 63. Dietary CE supplementation increased (P < 0.05) plasma total protein, albumin and glucose concentration, and decreased (P < 0.05) urea concentration. CE supplementation increased (P < 0.05) the villus height in the ileum and the villus height/crypt depth in the jejunum and ileum, but decreased (P < 0.05) the crypt depth in the jejunum and ileum. CE supplementation increased (P < 0.05) most plasma essential AA concentrations. Additionally, CE supplementation upregulated (P < 0.05) ASCT1, b0,+ AT, B0 AT1, EAAT3, rBAT, y+ LAT2 and PepT1 expression in the jejunum, and b0,+ AT, EAAT3, rBAT, y+ LAT2, CAT1 and PepT1 in the ileum. Collectively, our results indicated that CE supplementation promotes intestinal physiological absorption of AAs by upregulating gene expression of small intestinal key AA and peptide transporters, thereby enhancing the growth performance of broilers. © 2020 Society of Chemical Industry.

Uptake of dietary amino acids into arterial blood during continuous enteral feeding in critically ill patients and healthy subjects

Amino acid availability is a regulatory factor of protein anabolism and is partly dependent on enteral amino acid uptake. During continuous enteral feeding, enteral amino acid uptake may vary considerably, but this has not been documented systematically. In this pragmatic study, we investigated patients in the intensive care unit (n=10) and healthy adults (n=10). The time course of essential amino acid concentrations in arterial plasma and the uptake of dietary phenylalanine were recorded during 12hours of continuous enteral feeding, using a 13C-labeled phenylalanine tracer. Plasma essential amino acid concentrations and 13C-phenylalanine enrichment reached a tentative steady state after no more than 4.5h from start of tracer infusion. There was a large intra- and inter-individual variability in both cohorts. No periodicity could be detected in the temporal variation. During continuous enteral feeding, uptake of amino acids shows large intra- and inter-individual variation. A tentative steady state of 13C-phenylalanine uptake is eventually reached. Registered at Australian New Zealand Clinical Trials Registry, trial ID ACTRN12616000593437.

The Muscle Protein Synthetic Response Following Ingestion of Corn Protein, Milk Protein and Their Protein Blend in Young Males

Abstract Objectives The muscle protein synthetic response to the ingestion of animal based proteins has been reported to be superior to the ingestion of plant based proteins. The lesser anabolic properties of plant based compared with animal based proteins has been attributed to differences in essential amino acid (EAA) contents and amino acid composition. This study compares post-prandial muscle protein synthesis rates following the ingestion of 30 g milk protein with the ingestion of 30 g corn protein or a blend of 30 g corn and milk protein in vivo, in young males. Methods In a randomized, double blind, parallel-group design, 36 healthy young males (26 ± 4 y) received a primed continuous infusion of L-[ring-13C6]-phenylalanine and ingested 30 g milk protein (MILK), 30 g corn protein (CORN), or a blend of 15 g corn protein plus 15 g milk protein (CORN + MILK) (n = 12 per group). Blood and muscle biopsies were collected for 5 h following protein ingestion to assess post-prandial plasma amino acid profiles and myofibrillar protein synthesis rates. Data were analyzed with 2-way repeated measures ANOVA and independent samples t-test. Data are expressed as mean ± SD. Results MILK increased plasma EAA concentrations more when compared to CORN (incremental area under curve (iAUC): 151 ± 31 vs 77 ± 19 mmol/L/300 min, respectively; P &amp;lt; 0.001). Both milk and corn protein ingestion increased myofibrillar protein synthesis rates (P &amp;lt; 0.001), with no differences between MILK and CORN (from 0.014 ± 0.014 to 0.053 ± 0.013 and from 0.017 ± 0.011 to 0.052 ± 0.013%/h, respectively; time*treatment P = 0.661). When MILK was compared to CORN + MILK, the iAUC for plasma EAA concentrations increased more in MILK when compared to CORN + MILK (151 ± 31 vs 126 ± 24 mmol/L/300 min, respectively; P = 0.036). Corn plus milk protein ingestion also increased myofibrillar protein synthesis rates (from 0.015 ± 0.015 to 0.052 ± 0.024%/h; P &amp;lt; 0.001), with no differences between MILK and CORN + MILK (time*treatment P = 0.823). Conclusions Ingestion of 30 g milk protein, 30 g corn protein, or a blend of 15 g corn plus 15 g milk protein increases muscle protein synthesis rates in vivo in young males. Post-prandial muscle protein synthesis rates following the ingestion of 30 g milk protein do not differ from rates observed after ingesting 30 g corn protein or a blend providing 15 g milk plus 15 g corn protein in vivo, in young males. Funding Sources TiFN.

The glycation level of milk protein strongly modulates post-prandial lysine availability in humans.

Industrial heat treatment of milk results in protein glycation. A high protein glycation level has been suggested to compromise the post-prandial rise in plasma amino acid availability following protein ingestion. In the present study, we assessed the impact of glycation level of milk protein on post-prandial plasma amino acid responses in humans. Fifteen healthy, young men (age 26 (SEM 1) years, BMI 24 (SEM 1) kg/m2) participated in this randomised cross-over study and ingested milk protein powder with protein glycation levels of 3, 20 and 50 % blocked lysine. On each trial day, arterialised blood samples were collected at regular intervals during a 6-h post-prandial period to assess plasma amino acid concentrations using ultra-performance liquid chromatography. Plasma essential amino acid (EAA) concentrations increased following milk protein ingestion, with the 20 and 50 % glycated milk proteins showing lower overall EAA responses compared with the 3 % glycated milk protein (161 (SEM 7) and 142 (SEM 7) v. 178 (SEM 9) mmol/l × 6 h, respectively; P ≤ 0·011). The lower post-prandial plasma amino acid responses were fully attributed to an attenuated post-prandial rise in circulating plasma lysine concentrations. Plasma lysine responses (incremental AUC) following ingestion of the 20 and 50 % glycated milk proteins were 35 (SEM 4) and 92 (SEM 2) % lower compared with the 3 % glycated milk protein (21·3 (SEM 1·4) and 2·8 (SEM 0·7) v. 33·3 (SEM 1·7) mmol/l × 6 h, respectively; P < 0·001). Milk protein glycation lowers post-prandial plasma lysine availability in humans. The lower post-prandial availability of lysine following ingestion of proteins with a high glycation level may compromise the anabolic properties of a protein source.

Amino acid availability of protein meals of different quality for adult and growing mink (Neovison vison)

ABSTRACTProtein and amino acid (AA) availability of three protein meals of expected different quality were evaluated in young growing and adult mink. Lamb meal (LM), poultry meal (PM) or fishmeal (FM) were used as main protein sources in three extruded diets investigated by determining apparent total tract digestibility (ATTD) and nitrogen balance in 12 growing mink males aged 8–11 weeks in a Latin square design. In adult mink, ATTD of the diets was determined. The diets had lower protein content than recommended for growing mink, protein contributing 23% of total metabolisable energy (ME), to ensure differences in growth response. The LM diet with expected low protein quality revealed lower content of essential AA than the PM and FM diets. The ATTD of major nutrients and essential AA was significantly affected by diet, with the poorest values for LM, intermediate for PM and the highest values for FM. Mink kits revealed lower ATTD values than adults for protein, AA and especially fat, resulting in lower dietary ME content for kits than for adults. The mean difference was greatest for the LM diet with lowest ATTD and smallest for the FM diet with the highest ATTD. Nitrogen retention and growth rate differed significantly among diets and was lowest for diet LM and highest for diet FM, respectively. Different dietary essential AA contents and ATTD, especially of methionine, were the main factors to explain the difference in growth response. Generally, plasma essential AA concentrations did not clearly reflect the different dietary supply and the different growth response. The study shows that a recommended level of 0.31 g apparent total tract digestible methionine per MJ ME covers the minimum requirement with a safety margin. To obtain optimal growth, the lower digestive capacity in young mink kits should be considered when choosing feed ingredients.

Postprandial Amino Acid Kinetics of Milk Protein Mixtures are Affected by Composition, But Not Denaturation, in Neonatal Piglets

Multiple studies have indicated that formula-fed infants show a different growth trajectory compared with breastfed infants. The observed growth rates are suggested to be linked to higher postprandial levels of branched chain amino acids (BCAAs) and insulin related to differences in protein quality. We evaluated the effects of milk protein denaturation and milk protein composition on postprandial plasma and hormone concentrations. Neonatal piglets were bolus-fed randomly, in an incomplete crossover design, 2 of 3 milk protein solutions: native whey protein isolate (NWPI), denatured whey protein isolate (DWPI), or protein base ingredient, comprising whey and casein (PBI). Postprandial plasma amino acids (AAs), insulin, glucagon-like peptide 1, glucose, and paracetamol concentrations were assayed. Plasma responses were fitted with a model of first-order absorption with linear elimination. DWPI (91% denatured protein) compared with NWPI (91% native protein) showed lower essential amino acids (EAAs) (∼10%) and BCAA (13-19%) concentrations in the first 30-60 min. However, total amino acid (TAA) concentration per time-point and area under the curve (AUC), as well as EAA and BCAA AUC were not different. PBI induced a ∼30% lower postprandial insulin spike than NWPI, yet plasma TAA concentration at several time-points and AUC was higher in PBI than in NWPI. The TAA rate constant for absorption (k a) was twofold higher in PBI than in NWPI. Plasma BCAA levels from 60 to 180 min and AUC were higher in PBI than in NWPI. Plasma EAA concentrations and AUCs in PBI and NWPI were not different. Denaturation of WPI had a minimal effect on postprandial plasma AA concentration. The differences between PBI and NWPI were partly explained by the difference in AA composition, but more likely differences in protein digestion and absorption kinetics. We conclude that modifying protein composition, but not denaturation, of milk protein solutions impacts the postprandial amino acid availability in neonatal piglets.

Plasma essential amino acid concentrations in response to casein infusion or ration change in dairy cows: A multilevel, mixed-effects meta-analysis

The objectives of the current meta-analysis were to review the relationships between plasma individual essential AA concentrations and their respective AA digestible flows (AADI) in 2 independent sets of studies. The first set of studies included 36 casein infusion studies (CN; 83 treatment means) and was regarded as the best comparison standard available, because differences in AADI achieved by casein infusion (up to 40% of total metabolizable protein supply) did not rely on any model assumptions and were directly estimated from casein infusions. The second set of studies included 42 feeding trials (FT; 94 treatment means) in which AADI were predicted using the 2001 National Research Council model. The 2 sets of studies were not balanced for dry matter intake and the supplies of metabolizable protein and net energy for lactation; therefore, a subset of 17 CN studies (35 treatment means) and 19 FT trials (49 treatment means) balanced for these variables was assembled to allow the comparison of linear terms from CN and FT studies. In the subset of data set, the linear terms of individual AA did not differ between CN and FT studies except for Met and Thr, with a slope lower by 23 and 62%, respectively, in CN versus FT studies. The agreement in linear slopes between CN and FT studies indicates, indirectly, that AADI were predicted accurately by the National Research Council model. In the large data set, the relationships between plasma concentrations of Ile, Leu, Val, and their sum (branched-chain AA; BCAA) and their respective AADI shared common characteristics that distinguished them from the other AA. For the plasma concentration of BCAA, the linear terms were significant in CN and FT studies, but the quadratic terms were significant only in FT studies. This decline in the response of plasma concentration of BCAA to increased BCAA digestible flow in FT studies was associated with diets rich in energy, diets with a high concentrate level, or diets based on corn silage. These dietary conditions can stimulate insulin secretion and decrease plasma concentration of BCAA. For the non-BCAA, a quadratic term was significant for plasma His, Lys, Met, and Thr in each set of studies, indicating an increased removal of these AA by the liver as AADI increased.

Amino-acid-enriched cereals ready-to-use therapeutic foods (RUTF) are as effective as milk-based RUTF in recovering essential amino acid during the treatment of severe acute malnutrition in children: An individually randomized control trial in Malawi.

BackgroundReady-to-use therapeutic food (RUTF) is used to treat children suffering from severe acute malnutrition (SAM). Standard RUTF uses milk as the primary protein source, which makes the product expensive, and given the high worldwide SAM burden, having a less expensive effective alternative is a public health priority.ObjectiveThe objective of this study was to evaluate whether newly developed amino acid-enriched milk-free RUTF (FSMS-RUTF) or amino acid-enriched low-milk RUTF (MSMS-RUTF) treatment could replenish plasma amino acids to levels comparable to those following standard peanut-milk RUTF (PM-RUTF) treatment and to improve understanding of the effects of treatment on anthropometric measurements. A secondary analysis was performed to test the noninferiority hypothesis of plasma essential amino acid (EAA) levels.MethodsPlasma EAA levels were measured in a nonblinded, 3-arm, parallel-group simple randomized controlled trial conducted in Malawi to examine the efficacy of FSMS-RUTF, MSMS-RUTF and PM-RUTF in the treatment of SAM in 2 groups of children aged 6–23 and 24–59 months (mo). Sample size calculations were performed based on the previous our study. A noninferiority margin was set at -25% of the PM-RUTF arm at discharge.ResultsThe relative values of the differences (95% CI) in plasma EAA levels between PM-RUTF treatment and FSMS-RUTF and MSMS-RUTF treatments at discharge were -7.9% (-18.6, 2.8) and 9.8% (0.2, 19.5), respectively, in children aged 6–23 mo, while in those aged 24–59 mo, the difference values were 17.8% (1.6, 34.1) and 13.6% (-2.8, 29.9), respectively.ConclusionAt discharge, the plasma EAA concentrations in 6-59-mo-old SAM children treated with FSMS-RUTF and MSMS-RUTF were not less than those of children treated with PM-RUTF. These findings indicate that treatment with either of the 3 RUTFs was associated with adequate protein synthesis and that all the formulations provided sufficient functional metabolites of plasma amino acids to support nutritional recovery from SAM.