EAA (필수 아미노산)

Impact of protein-rich meals on glycaemic response of rice.

1. Br J Nutr. 2016 Apr 14;115(7):1194-201. doi: 10.1017/S0007114515005498. Epub 2016 Feb 9. Impact of protein-rich meals on glycaemic response of rice. Quek R(1), Bi X(1), Henry CJ(1). Author information: (1)1Clinical Nutrition Research Centre,Singapore Institute for Clinical Sciences,14 Medica

Combined resistance exercise and essential amino acid intake enhance follistatin/myostatin ratio and muscle fitness in older women: a randomized controlled trial.

1. J Int Soc Sports Nutr. 2026 Dec 31;23(1):2646626. doi: 10.1080/15502783.2026.2646626. Epub 2026 Mar 21. Combined resistance exercise and essential amino acid intake enhance follistatin/myostatin ratio and muscle fitness in older women: a randomized controlled trial. Jeong D(1)(2), Valentine RJ(2), Jeong H(3), Sung JY(4), Lim H(5), Kang S(1)(3). Author information: (1)Department of Smart Health Science and Technology, Kangwon National University, Gangwon-do, Republic of Korea. (2)Department of Physical Therapy & Kinesiology, University of Massachusetts Lowell, Lowell, MA, United States. (3)Department of Sport Science, Kangwon National University, Gangwon-do, Republic of Korea. (4)Institute of Sports Medicine & Nutrition, Kwangwoon University, Seoul, Republic of Korea. (5)Querencia, a Forest Walfare Business, Gangwon-do, Republic of Korea. BACKGROUND: Age-associated sarcopenia and declining physical function in older women are connected to changes in hormones, inflammation, and disrupted protein metabolism. Myokines and cytokines play central roles in muscle atrophy. While both resistance exercise (RE) and essential amino acid (EAA) supplementation are promising interventions, limited randomized trials have assessed their combined effect in healthy elderly populations. Early targeted strategies may help delay sarcopenia and promote healthier aging. METHODS: A 12-week randomized controlled trial was performed involving 96 healthy women aged ≥ 65 years without insulin resistance. Participants were randomized into four groups: control, RE, EAA, or RE + EAA. The intervention consisted of a circuit-based training program conducted three times per week, with each session lasting 60 minutes at moderate intensity. Participants in EAA and RE + EAA groups consumed 5.5g of EAA twice daily. Assessments before and after the intervention included body composition, muscle fitness, serum myokines, and inflammatory cytokines. Data analysis involved two-way repeated measures ANOVA, Bonferroni post-hoc comparisons, and one-way ANOVA for changes in the follistatin/myostatin ratio. RESULTS: The RE + EAA group demonstrated a significant increase in muscle mass (F(3, 72) = 5.042, p < 0.001, partial η² = 0.174) and greater improvements in the senior fitness test (p ranging from < 0.05 to < 0.001). There was a reduction in myostatin levels (p < 0.05) and an elevation in follistatin in both the RE (p < 0.05) and RE + EAA (p < 0.001) groups. The follistatin/myostatin ratio increased most in the RE + EAA group (F(3, 72) = 5.556, p = 0.002, partial η² = 0.188), with significance versus control (p < 0.001), EAA (p < 0.05) groups. IL-6 and IL-1β were significantly reduced in the RE (p < 0.05) and RE + EAA (p < 0.05) groups, whereas TNF-α decreased only in the RE + EAA group (p < 0.05). CONCLUSION: A 12-week intervention combining resistance exercise and essential amino acid supplementation was superior to either intervention alone in enhancing muscle mass, muscle fitness, myokine profiles, and reducing inflammatory markers among healthy older women. These results support the development of early combined interventions for the prevention of sarcopenia and may guide personalized exercise-nutrition prescriptions for optimal aging. TRIAL REGISTRATION: KCT 0010756 (Retrospectively registered; July 15, 2025). DOI: 10.1080/15502783.2026.2646626 PMCID: PMC13007441 PMID: 41863133 [Indexed for MEDLINE] Conflict of interest statement: The authors declare that there are no competing interests related to this work.

Combined resistance training and amino acid-based supplementation for sarcopenia in older adults: a systematic review and meta-analysis.

2. BMC Musculoskelet Disord. 2026 Jan 15;27(1):35. doi: 10.1186/s12891-025-09436-8. Combined resistance training and amino acid-based supplementation for sarcopenia in older adults: a systematic review and meta-analysis. Xie C(1)(2), Yan R(3), Tao R(4). Author information: (1)School of Physical Education and Sports, Central China Normal University, Hubei, China. (2)School of Sports Economics and Management, Hubei University of Economics, Hubei, China. (3)School of Athletic Training, Guangzhou Sport University, Guangzhou, Guangdong, China. (4)School of Sports Economics and Management, Hubei University of Economics, Hubei, China. Taoran19800830@163.com. BACKGROUND AND OBJECTIVE: Resistance training is the cornerstone of sarcopenia management. However, whether combining it with amino acid-based supplementation, including essential amino acids, branched-chain amino acids, leucine, and derivatives such as HMB, provides additional benefits remains unclear. METHODS: We systematically searched PubMed, Embase, Web of Science, and the Cochrane Central Register of Controlled Trials until February 2025. Meta- and subgroup analyses were performed using a random-effects model. The Cochrane ROB2 tool and GRADE framework were used to assess the risk of bias and evidence certainty. RESULTS: We included nine randomized controlled trials involving 496 participants with sarcopenia. Evidence rated as low to very low certainty indicated that, compared with resistance training alone, combined amino acid supplementation and resistance training significantly improved handgrip strength (SMD = 0.69, 95% CI: 0.04 to 1.35), gait speed (SMD = 0.64, 95% CI: 0.02 to 1.25), Short Physical Performance Battery scores (SMD = 1.69, 95% CI: 0.81 to 2.57), and Five Times Sit-to-Stand Test performance (SMD = -1.42, 95% CI: -2.68 to -0.16). No significant effects were observed for skeletal muscle mass index or appendicular skeletal muscle mass. Subgroup analyses showed that baseline protein intake, intervention setting, amino acid supplement type, resistance-training frequency, and whether the supplement contained co-nutrients were significant effect modifiers. CONCLUSION: Resistance training combined with amino acid supplementation may improve muscle strength and physical function in older adults with sarcopenia, although effects on muscle mass remain limited. Responsiveness to the intervention may vary by baseline protein intake, training frequency, setting, type of amino acid supplementation, and whether the supplement includes co-nutrients, all of which should be considered when designing sarcopenia management strategies. © 2026. The Author(s). DOI: 10.1186/s12891-025-09436-8 PMCID: PMC12809905 PMID: 41540398 [Indexed for MEDLINE] Conflict of interest statement: Declarations. Ethics approval and consent to participate: Not applicable. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests.

Dileucine-supplemented essential amino acids support whole-body anabolism after resistance exercise and serum-stimulated cell-based anabolism.

3. J Int Soc Sports Nutr. 2025 Dec 31;22(1):2590090. doi: 10.1080/15502783.2025.2590090. Epub 2025 Nov 30. Dileucine-supplemented essential amino acids support whole-body anabolism after resistance exercise and serum-stimulated cell-based anabolism. Aguilera JA(1), Tinline-Goodfellow CT(1), Lees MJ(1), Kortebi I(1), West DWD(1)(2), Abou Sawan S(3), Sharma M(3), Bashir R(3), Barnes TM(4), Ulanov AV(5), Burd NA(4)(6), Moore DR(1). Author information: (1)Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON, Canada. (2)KITE Research Institute, Toronto Rehabilitation Institute, Toronto, ON, Canada. (3)Iovate Health Sciences International Inc, Oakville, ON, Canada. (4)Department of Health and Kinesiology, University of Illinois Urbana-Champaign, Urbana, IL, USA. (5)Roy J. Carver Biotechnology Center, University of Illinois Urbana-Champaign, Urbana, IL, USA. (6)Division of Nutritional Sciences, University of Illinois Urbana-Champaign, Urbana, IL, USA. BACKGROUND: Essential (EAA) and branched chain (BCAA) amino acid ingestion support whole-body anabolism after resistance exercise and can attenuate markers of postexercise myofibrillar protein breakdown (i.e. urinary 3-methylhistidine; 3MH). Leucine is often considered a primary anabolic EAA through its ability to activate the mechanistic target of rapamycin complex 1 (mTORC1) and stimulate muscle protein synthesis. The dipeptide leucine (dileucine) has been shown to more effectively stimulate myofibrillar protein synthesis than leucine in young males at rest. Therefore, we aimed to determine the effect of a dileucine-containing essential amino acid formula (DIEAA; 2 g dileucine, 1 g leucine, 9.15 g total EAA) on the anabolic and catabolic responses following resistance exercise in young recreationally active adults when compared with ingesting branched chain amino acids (BCAA; 3 g leucine, 1.5 g isoleucine, 1.5 g valine) or isonitrogenous (to DIEAA) collagen hydrolysate (COL). METHODS: In a randomized, double-blind, crossover design, 12 healthy adults (8 M, 4F, aged 24 ± 3 y) performed a 60 min bout of whole-body resistance exercise, after which they ingested DIEAA, BCAA, or COL protein beverages containing 100 mg L-[1-13C]leucine (#NCT05754125). Total exogenous leucine retention (as an estimate of whole-body anabolism) was assessed over the 6 h postprandial period by determining total leucine oxidation from 13CO2 enrichment (isotope ratio mass spectrometry) in repeated breath samples. A urinary 3MH:creatinine ratio (3MH:Cr) over 6 h was used as an estimate of skeletal muscle myofibrillar protein breakdown. To further assess the anabolic potential of nutrients, C2C12 myotubes were treated with a subset (n = 7) of human serum-conditioned media for 4 h to measure downstream mTORC1 substrate phosphorylation, protein synthesis (puromycin and L-ring-[D5]phenylalanine incorporation) and breakdown (ubiquitinated protein), and myotube hypertrophy. RESULTS: Total exogenous leucine retention were similar (p = 0.68) between DIEAA (215.72 ± 42.45 μmol·kg-1) and BCAA conditions (219.15 ± 45.26 μmol·kg-1), with both DIEAA and BCAA being greater (p < 0.0001) than COL (37.25 ± 8.16 μmol·kg-1). There were no differences (p = 0.58) in 3MH:Cr between supplement conditions. There was no effect of condition ex vivo on puromycin incorporation into nascent peptides (p = 0.31), total protein ubiquitination as an estimate of protein breakdown (p = 0.59), phosphorylation of downstream mTORC1 substrates p-RPS6S240/244 (p = 0.39) or p-4E-BP1T37/46 (p = 0.50), and myotube diameter (p = 0.55). Stable isotope-derived rates of mixed muscle protein synthesis (MPS) demonstrated a trend toward a main effect (p = 0.086) with pairwise comparisons revealing a large effect of DIEAA compared to COL (dz = 1.47), a medium effect of DIEAA compared to BCAA (dz = 0.81), and a trivial effect of BCAA comapred to COL (dz = 0.002). CONCLUSIONS: Dileucine-supplemented EAA and BCAA support greater whole-body anabolism compared with COL after resistance exercise independent of attenuation in urinary estimates of myofibrillar protein breakdown. Exploratory ex vivo experiments reveal a potential anabolic effect of DIEAA in stimulating MPS. Collectively, these findings suggest that consuming dileucine with sufficient EAA and BCAA increases exogenous leucine retention to support whole-body anabolism during postexercise recovery in individuals performing resistance training. DOI: 10.1080/15502783.2025.2590090 PMCID: PMC12671060 PMID: 41321015 [Indexed for MEDLINE] Conflict of interest statement: S.A.S., M.S. and R.B. are employees of Iovate Health Sciences and developed the investigational supplements. S.A.S., M.S and R.B were not involved in data collection, analysis, interpretation of data, or the decision to publish the results but did review the final manuscript draft.

The Effect of Leucine-Enriched β-Lactoglobulin Versus an Isonitrogenous Whey Protein Isolate on Skeletal Muscle Protein Anabolism in Young Healthy Males.

4. Nutrients. 2025 Oct 30;17(21):3410. doi: 10.3390/nu17213410. The Effect of Leucine-Enriched β-Lactoglobulin Versus an Isonitrogenous Whey Protein Isolate on Skeletal Muscle Protein Anabolism in Young Healthy Males. Ely IA(1), Paul M(1)(2), Wall JJS(1)(2), Cox J(1), Larsen MS(3), Scaife PJ(1), Lund JN(1)(2), Breen L(4), Wilkinson DJ(1), Smith K(1), Phillips BE(1), Atherton PJ(1)(5). Author information: (1)Centre of Metabolism Ageing & Physiology, School of Medicine, Nottingham NIHR Biomedical Research Centre, MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research (CMAR), University of Nottingham, Royal Derby Hospital, Derby DE22 3DT, UK. (2)Department of Surgery, Royal Derby Hospital, Derby DE22 3NE, UK. (3)Arla Foods Ingredients Group P/S, 8260 Viby J, Denmark. (4)Diabetes Research Centre, College of Life Sciences, University of Leicester, Leicester LE5 4PW, UK. (5)Department of Sport and Health Sciences, Ritsumeikan University, Kyoto 603-8577, Japan. BACKGROUND: β-lactoglobulin (BLG) is a protein found within whey protein (WP) that is rich in essential amino acids, most notably, leucine (LEU). LEU is considered the most potent EAA in the postprandial stimulation of muscle protein synthesis (MPS), such that suboptimal protein/essential amino acid (EAA) doses containing higher LEU content elicit muscle anabolism comparable to larger protein doses. Our objective was to test the effects of naturally LEU-rich BLG (~10 g protein) versus isonitrogenous whey protein isolate (WPI, ~10 g) on MPS. METHODS: Ten healthy young men (26 ± 2 y; 179 ± 2 cm; 81 ± 3 kg) received BLG (1.57 g LEU) or WPI (1.02 g LEU) in a randomised double-blind cross-over fashion. A primed constant intravenous infusion of [1,2 13C2] LEU was used to determine MPS (isotope ratio mass spectrometry) at baseline and in response to feeding (FED) and feeding-plus-exercise (FED-EX; 6 × 8 unilateral leg extensions; 75% 1-RM). Plasma insulin and EAA's were quantified. RESULTS: Plasma EAA, branched-chain amino acid (BCAA), and LEU concentrations increased rapidly following both protein supplements but exhibited a significantly greater EAA/BCAA/leucinemia following BLG (p < 0.05 for all). MPS increased significantly in both FED (~52%) and FED-EX (~58%) states, with no significant differences between supplements. CONCLUSIONS: Both BLG and WPI effectively stimulated MPS doses in young healthy males, with BLG offering an advantage in EAA/BCAA/LEU bioavailability. It follows that future research should explore the potential of BLG in populations exhibiting anabolic resistance and exercise anabolism deficiency, such as older adults as well as frail and clinical populations, to assess its utility in preserving muscle mass under conditions of suboptimal protein intake. DOI: 10.3390/nu17213410 PMCID: PMC12611059 PMID: 41228483 [Indexed for MEDLINE] Conflict of interest statement: This study was funded by Arla Food Ingredients (AFI) with whom M.S.L is an employee. B.E.P and P.J.A declare honoraria and research funding from Abbott Nutrition (B.E.P) and honoraria, consultancy, and research funding from AFI, Abbott Nutrition and Fresenius-Kabi (P.J.A).

Effects of Pork Protein Ingestion Prior to and Following Performing the Army Combat Fitness Test on Markers of Catabolism, Inflammation, and Recovery.

5. Nutrients. 2025 Jun 13;17(12):1995. doi: 10.3390/nu17121995. Effects of Pork Protein Ingestion Prior to and Following Performing the Army Combat Fitness Test on Markers of Catabolism, Inflammation, and Recovery. Gonzalez DE(1), Hines KE(1), Sowinski RJ(1), Estes L(1), Johnson SE(1), Chun J(1), Lee H(1), Leon S(1), Gil A(1), Ko J(1), Broeckel J(1), Barringer ND(2), Rasmussen CJ(1), Kreider RB(1). Author information: (1)Exercise & Sport Nutrition Laboratory, Department of Kinesiology and Sport Management, Texas A&M University, College Station, TX 77843, USA. (2)Lionel University, Carpinteria, CA 93013, USA. Tactical athletes and military personnel engaged in intense exercise need to consume enough quality protein in their diet to maintain protein balance and promote recovery. Plant-based protein sources contain fewer essential amino acids (EAAs), while pork loin contains a higher concentration of EAAs and creatine than most other animal protein sources. This study aimed to determine whether the ingestion of plant-based or pork-based military-style meals ready-to-eat (MREs) affects recovery from and subsequent Army Combat Fitness Test (ACFT) performance. Methods: Twenty-three (n = 23) University Corps of Cadets members participated in a randomized, double-blind, placebo-controlled, and crossover-designed study. Diets were prepared by a dietitian, food scientist, and chef to have similar taste, appearance, texture, and macronutrient content. The chef also labeled the meals for double-blind administration. Participants refrained from intense exercise for 48 h before reporting to the lab in a fasted condition with a 24 h urine sample. Participants donated a blood sample, completed questionnaires and cognitive function tests, and consumed a pre-exercise meal. After four hours, participants performed the ACFT according to military standards. Participants were fed three MREs daily while returning to the lab in a fasted condition at 0600 with 24 h urine samples after 24, 48, and 72 h of recovery. On day 3, participants repeated the ACFT four hours after consuming an MRE for breakfast. Participants resumed normal training and returned to the lab after 2-3 weeks to repeat the experiment while consuming the alternate diet. Data were analyzed using general linear model statistics with repeated measures and percent changes from baseline with 95% confidence intervals. Results: Results revealed that 3 days were sufficient for participants to replicate ACFT performance. However, those consuming the pork-based diet experienced less muscle soreness, urinary urea excretion, cortisol, inflammation, and depression scores while experiencing a higher testosterone/cortisol ratio and appetite satisfaction. There was also evidence of more favorable changes in red and white blood cells. Conversely, blood lipid profiles were more favorably changed when following a plant-based diet. Conclusions: These findings suggest that protein quality and the availability of creatine in the diet can affect recovery from intense military-style exercise. Minimally, plant-based MREs should include 6-10 g/d of EAA and 2-3 g/d of creatine monohydrate to offset dietary deficiencies, particularly in military personnel following a vegetarian diet. Registered clinical trial #ISRCTN47322504. DOI: 10.3390/nu17121995 PMCID: PMC12195741 PMID: 40573107 [Indexed for MEDLINE] Conflict of interest statement: R.B.K. has conducted grant and contract-funded research on nutritional supplements awarded to the universities he has been affiliated with, received honorariums for making scientific presentations, and served as a paid scientific expert. He has no financial conflict of interest with the study sponsor or product evaluated in this study. The remaining coauthors report no financial conflicts of interest.

Nutritional Management in Stricturing Crohn's Disease: A Pilot Study.

6. Nutrients. 2024 Nov 29;16(23):4153. doi: 10.3390/nu16234153. Nutritional Management in Stricturing Crohn's Disease: A Pilot Study. Cavalcanti E(1), Marra A(1), Mileti A(1), Donghia R(2), Curlo M(1), Mastronardi M(1). Author information: (1)IBD Unit, National Institute of Gastroenterology-IRCCS, 70013 Castellana Grotte, Italy. (2)Data Science Unit, National Institute of Gastroenterology-IRCCS, 70013 Castellana Grotte, Italy. BACKGROUND: More than half of patients with Crohn's disease develop intestinal fibrosis induced intestinal obstruction with debilitating symptoms throughout their disease course. The incidence of stricture formation in CD has remained unchanged over the last several decades. Factors promoting intestinal fibrosis are currently unclear, but diet may represent an underestimated risk factor for intestinal fibrosis by modification of both the host immune response and intestinal microbial composition. Evaluating the impact of diet on the course of IBD is very complex. Sarcopenia is a common problem in IBD patients and correlates with an increased rate of disease. Skeletal muscle index (SMI) is an important parameter to measure sarcopenia and is an easily accessible tool for evaluating the likelihood of complications in individuals with CD. METHODS: Using a randomized and controlled pilot design, we aimed to investigate the efficacy of 12 months of short-term dietary intervention based on essential amino acid (EAA) and sodium butyrate (NaB) supplementation in the management of stricturing Crohn's disease patients. RESULTS: After the treatment in the diet EAA/NaB group, we revealed a statistically significant improvement of muscle mass (61.49 ± 5.47 vs. control 86 ± 10.70, p = 0.01) and SMI index (9.97 ± 1.79 vs. control 7.60 ± 2.29, p = 0.02). In addition, the measurement of skeletal muscle mass in CD patients has been suggested to be crucial for predicting the disease course. Indeed, after one year, surgery was required in 4/10 control group patients (40%) and 1/10 study group (10%) patients, underlining the importance of body composition alterations and adequate dietary intake in the management of these patients. CONCLUSIONS: Further prospective studies are needed to confirm these results; nonetheless this nutritional approach could become an integral part in the treatment of stricturing CD patients to improve disease outcomes and increase the quality of life in these patients. DOI: 10.3390/nu16234153 PMCID: PMC11644502 PMID: 39683547 [Indexed for MEDLINE] Conflict of interest statement: The authors declare no conflict of interest.

Consuming Whey Protein with Added Essential Amino Acids, Not Carbohydrate, Maintains Postexercise Anabolism While Underfed.

7. Med Sci Sports Exerc. 2025 Jan 1;57(1):70-80. doi: 10.1249/MSS.0000000000003541. Epub 2024 Aug 23. Consuming Whey Protein with Added Essential Amino Acids, Not Carbohydrate, Maintains Postexercise Anabolism While Underfed. Gwin JA(1), Church DD(2), Allen JT(1), Wilson MA(1), Carrigan CT(1), Murphy NE(1), Varanoske AN, Margolis LM(1), Wolfe RR(2), Ferrando AA(2), Pasiakos SM(1). Author information: (1)Military Nutrition Division, U.S. Army Research Institute of Environmental Medicine, Natick, MA. (2)Department of Geriatrics, Donald W. Reynolds Institute on Aging, Center for Translational Research in Aging & Longevity, University of Arkansas for Medical Sciences, Little Rock, AR. PURPOSE: Energy deficiency decreases muscle protein synthesis (MPS), possibly due to greater whole-body essential amino acid (EAA) requirements and reliance on energy stores. Whether energy deficit-induced anabolic resistance is overcome with non-nitrogenous supplemental energy or if increased energy as EAA is needed is unclear. We tested the effects of energy as EAA or carbohydrate, combined with an EAA-enriched whey protein, on postexercise MPS (%·h -1 ) and whole-body protein turnover (g protein·240 min -1 ). METHODS: Seventeen adults (mean ± SD; age: 26 ± 6 yr, body mass index: 25 ± 3 kg·m -2 ) completed a randomized, parallel study including two 5-d energy conditions (BAL; energy balance; daily energy requirements (DEF), -30% ± 3% energy requirements) separated by ≥7 d. Volunteers consumed EAA-enriched whey with added EAA (+EAA; 304 kcal, 56 g protein, 48 g EAA, 17 g carbohydrate, 2 g fat; n = 8) or added carbohydrate (+CHO; 311 kcal, 34 g protein, 24 g EAA, 40 g carbohydrate, 2 g fat; n = 9) following exercise. MPS and whole-body protein synthesis (PS), breakdown (PB), and net balance (NET; PS-PB) were estimated postexercise with isotope kinetics. RESULTS: MPS rates were greater in +EAA (0.083 ± 0.02) than +CHO (0.059 ± 0.01; P = 0.015) during daily energy requirements, but similar during BAL ( P = 0.45) and across energy conditions within treatments ( P = 0.056). PS rates were greater for +EAA (BAL, 117.9 ± 16.5; daily energy requirements, 110.3 ± 14.8) than +CHO (BAL, 81.6 ± 8.0; daily energy requirements, 83.8 ± 5.9 g protein·240 min -1 ; both P < 0.001) and greater during BAL than daily energy requirements in +EAA ( P = 0.045). PB rates were less in +EAA (8.0 ± 16.5) than +CHO (37.8 ± 7.6 g protein·240 min -1 ; P < 0.001), and NET was greater in +EAA (106.1 ± 6.3) than +CHO (44.8 ± 8.5 g protein·240 min -1 ; P < 0.001). CONCLUSIONS: These data suggest that supplementing EAA-enriched whey protein with more energy as EAA, not carbohydrate, maintains postexercise MPS during energy deficit at rates comparable to those observed during energy balance. Copyright © 2025 Written work prepared by employees of the Federal Government as part of their official duties is, under the U.S. Copyright Act, a “work of the United States Government” for which copyright protection under Title 17 of the United States Code is not available. As such, copyright does not extend to the contributions of employees of the Federal Government. DOI: 10.1249/MSS.0000000000003541 PMID: 39160756 [Indexed for MEDLINE]

Effects of Resistance Exercise and Essential Amino Acid Intake on Muscle Quality, Myokine, and Inflammation Factors in Young Adult Males.

8. Nutrients. 2024 May 29;16(11):1688. doi: 10.3390/nu16111688. Effects of Resistance Exercise and Essential Amino Acid Intake on Muscle Quality, Myokine, and Inflammation Factors in Young Adult Males. Jeong D(1), Park K(2), Lee J(3), Choi J(1), Du H(1), Jeong H(3), Li L(3), Sakai K(4), Kang S(1)(3). Author information: (1)Department of Smart Health Science and Technology, Kangwon National University, Chuncheon 24341, Gangwon-do, Republic of Korea. (2)Center for Sports Science in Gangwon, Chuncheon 24239, Gangwon-do, Republic of Korea. (3)Department of Sport Science, Kangwon National University, Chuncheon 24341, Gangwon-do, Republic of Korea. (4)Chemicals & Life Science Division, Nagase Korea Corporation, Seoul 04527, Republic of Korea. BACKGROUND: Recently, many studies have been devoted to discovering nutrients for exercise-like effects. Resistance exercise and the intake of essential amino acids (EAAs) are known to be factors that can affect muscle mass and strength improvement. The purpose of this study was to investigate changes in muscle quality, myokines, and inflammation in response to resistance exercise and EAA supplementation. METHODS: Thirty-four males volunteered to participate in this study. They were assigned to four groups: (1) placebo (CO), (2) resistance exercise (RE), (3) EAA supplementation, and (4) RE + EAA supplementation. Body composition, muscle quality, myokines, and inflammation were measured at baseline and four weeks after treatment. RESULTS: Lean body fat had decreased in both RE and RE + EAA groups. Lean body mass had increased in only the RE + EAA group. In all groups except for CO, irisin, myostatin A, and TNF-α levels had decreased. The grip strength of the right hand and trunk flexion peak torque increased in the RE group. The grip strength of the left hand, trunk flexion peak torque, and knee flexion peak torque of the left leg were increased in RE + EAA. CONCLUSIONS: RE, EAA, and RE + EAA could effectively improve the muscle quality, myokine, and inflammation factors of young adult males. This finding highlights the importance of resistance exercise and amino acid intake. DOI: 10.3390/nu16111688 PMCID: PMC11174838 PMID: 38892621 [Indexed for MEDLINE] Conflict of interest statement: Author Kenji Sakai was employed by the Nagase Korea Corporation. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Acute Microbial Protease Supplementation Increases Net Postprandial Plasma Amino Acid Concentrations After Pea Protein Ingestion in Healthy Adults: A Randomized, Double-Blind, Placebo-Controlled Trial.

9. J Nutr. 2024 May;154(5):1549-1560. doi: 10.1016/j.tjnut.2024.03.009. Epub 2024 Mar 11. Acute Microbial Protease Supplementation Increases Net Postprandial Plasma Amino Acid Concentrations After Pea Protein Ingestion in Healthy Adults: A Randomized, Double-Blind, Placebo-Controlled Trial. Paulussen KJM(1), Askow AT(1), Deutz MT(2), McKenna CF(2), Garvey SM(3), Guice JL(3), Kesler RM(4), Barnes TM(1), Tinker KM(3), Paluska SA(1), Ulanov AV(5), Bauer LL(6), Dilger RN(7), Burd NA(8). Author information: (1)Department of Health and Kinesiology, University of Illinois Urbana-Champaign, Urbana, IL, United States. (2)Division of Nutritional Sciences, University of Illinois Urbana-Champaign, Urbana, IL, United States. (3)Department of Research and Development, BIO-CAT, Inc., Troy, VA, United States. (4)Department of Health and Kinesiology, University of Illinois Urbana-Champaign, Urbana, IL, United States; Illinois Fire Service Institute, University of Illinois Urbana-Champaign, Urbana, IL, United States. (5)Roy J. Carver Biotechnology Center, University of Illinois Urbana-Champaign, Urbana, IL, States. (6)Department of Animal Sciences, University of Illinois Urbana-Champaign, Urbana, IL, United States. (7)Division of Nutritional Sciences, University of Illinois Urbana-Champaign, Urbana, IL, United States; Department of Animal Sciences, University of Illinois Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, IL, United States. (8)Department of Health and Kinesiology, University of Illinois Urbana-Champaign, Urbana, IL, United States; Division of Nutritional Sciences, University of Illinois Urbana-Champaign, Urbana, IL, United States. Electronic address: naburd@illinois.edu. BACKGROUND: Digestibility is a primary factor in determining the quality of dietary protein. Microbial protease supplementation may be a strategy for improving protein digestion and subsequent postprandial plasma amino acid availability. OBJECTIVES: To assess the effect of co-ingesting a microbial protease mixture with pea protein on postprandial plasma amino acid concentrations. DESIGN: A mixture of 3 microbial protease preparations (P3) was tested for proteolytic efficacy in an in vitro static simulation of gastrointestinal digestion. Subsequently, in a randomized, double-blind, placebo-controlled crossover trial, 24 healthy adults (27 ± 4 y; 12 females, 12 males) ingested 25 g pea protein isolate (20 g protein, 2.2 g fat) with either P3 or maltodextrin placebo (PLA). Blood samples were collected at baseline and throughout a 0‒5 h postprandial period and both the early (0-2 h) iAUC and total (0-5 h) iAUC were examined. RESULTS: Plasma glucose concentrations decreased in both conditions (P < 0.001), with higher concentrations after P3 ingestion compared with PLA (P < 0.001). Plasma insulin concentrations increased for both conditions (P < 0.001) with no difference between conditions (P = 0.331). Plasma total amino acid (TAA) concentrations increased over time (P < 0.001) with higher concentrations observed for P3 compared with PLA (P = 0.010) during the 0‒5 h period. There was a trend for elevated essential amino acid (EAA) concentrations for P3 compared with PLA (P = 0.099) during the 0‒5 h postprandial period but not for leucine (P = 0.282) or branched-chain amino acids (BCAA, P = 0.410). The early net exposure (0‒2 h iAUC) to amino acids (leucine, BCAA, EAA, and TAA) was higher for P3 compared with PLA (all, P < 0.05). CONCLUSIONS: Microbial protease co-ingestion increases plasma TAA concentrations (0-5 h) and leucine, BCAA, EAA, and TAA availability in the early postprandial period (0‒2 h) compared with ingesting pea protein with placebo in healthy adults. Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved. DOI: 10.1016/j.tjnut.2024.03.009 PMCID: PMC11130700 PMID: 38467279 [Indexed for MEDLINE]

Metabolic effects of an essential amino acid supplement in adolescents with PCOS and obesity.

10. Obesity (Silver Spring). 2024 Apr;32(4):678-690. doi: 10.1002/oby.23988. Epub 2024 Mar 4. Metabolic effects of an essential amino acid supplement in adolescents with PCOS and obesity. Fordham TM(1), Morelli NS(2), Garcia-Reyes Y(2), Ware MA(2), Rahat H(2), Sundararajan D(2), Fuller KNZ(2), Severn C(3), Pyle L(3)(4), Malloy CR(5)(6)(7)(8), Jin ES(5)(6), Parks EJ(1), Wolfe RR(9), Cree MG(2)(10). Author information: (1)Department of Nutrition and Exercise Physiology, University of Missouri School of Medicine, Columbia, Missouri, USA. (2)Department of Pediatrics, Section on Endocrinology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA. (3)Child Health Biostatistics Core, Department of Pediatrics, Section of Endocrinology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA. (4)Department of Biostatistics and Informatics, Colorado School of Public Health, Aurora, Colorado, USA. (5)Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA. (6)Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA. (7)Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA. (8)VA North Texas Health Care System, Dallas, Texas, USA. (9)Department of Geriatrics, Donald W. Reynolds Institute on Aging, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA. (10)Center for Women's Health Research, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA. OBJECTIVE: Polycystic ovary syndrome (PCOS) is characterized by hyperandrogenism, insulin resistance, and hepatic steatosis (HS). Because dietary essential amino acid (EAA) supplementation has been shown to decrease HS in various populations, this study's objective was to determine whether supplementation would decrease HS in PCOS. METHODS: A randomized, double-blind, crossover, placebo-controlled trial was conducted in 21 adolescents with PCOS (BMI 37.3 ± 6.5 kg/m2, age 15.6 ± 1.3 years). Liver fat, very low-density lipoprotein (VLDL) lipogenesis, and triacylglycerol (TG) metabolism were measured following each 28-day phase of placebo or EAA. RESULTS: Compared to placebo, EAA was associated with no difference in body weight (p = 0.673). Two markers of liver health improved: HS was lower (-0.8% absolute, -7.5% relative reduction, p = 0.013), as was plasma aspartate aminotransferase (AST) (-8%, p = 0.004). Plasma TG (-9%, p = 0.015) and VLDL-TG (-21%, p = 0.031) were reduced as well. VLDL-TG palmitate derived from lipogenesis was not different between the phases, nor was insulin sensitivity (p > 0.400 for both). Surprisingly, during the EAA phase, participants reported consuming fewer carbohydrates (p = 0.038) and total sugars (p = 0.046). CONCLUSIONS: Similar to studies in older adults, short-term EAA supplementation in adolescents resulted in significantly lower liver fat, AST, and plasma lipids and thus may prove to be an effective treatment in this population. Additional research is needed to elucidate the mechanisms for these effects. © 2024 The Authors. Obesity published by Wiley Periodicals LLC on behalf of The Obesity Society. DOI: 10.1002/oby.23988 PMID: 38439205 [Indexed for MEDLINE]

Perioperative Essential Amino Acid Supplementation Facilitates Quadriceps Muscle Strength and Volume Recovery After TKA: A Double-Blinded Randomized Controlled Trial.

11. J Bone Joint Surg Am. 2023 Mar 1;105(5):345-353. doi: 10.2106/JBJS.22.00675. Epub 2023 Mar 1. Perioperative Essential Amino Acid Supplementation Facilitates Quadriceps Muscle Strength and Volume Recovery After TKA: A Double-Blinded Randomized Controlled Trial. Ueyama H(1)(2)(3), Kanemoto N(2), Minoda Y(3), Taniguchi Y(2), Nakamura H(3). Author information: (1)Department of Orthopedic Surgery, Osaka Rosai Hospital, Sakai, Osaka, Japan. (2)Department of Orthopedic Surgery, Tanabe Central Hospital, Tanabe City, Wakayama, Japan. (3)Department of Orthopedic Surgery, Osaka Metropolitan University Graduate School of Medicine, Osaka City, Japan. Comment in J Bone Joint Surg Am. 2023 Mar 1;105(5):e16. doi: 10.2106/JBJS.22.01357. BACKGROUND: Perioperative essential amino acid (EAA) supplementation suppresses lower-limb muscle atrophy and promotes functional improvement in the first 4 weeks after total knee arthroplasty (TKA). However, its effect on the recovery of muscle volume and strength in the intermediate term is unclear. The aim of this study was to evaluate the effect of perioperative EAA supplementation on the recovery of lower-limb muscle volume and strength in the 2 years after TKA. METHODS: Sixty patients who underwent unilateral TKA for primary knee osteoarthritis were included in this double-blinded randomized controlled trial. After excluding dropouts, 26 patients assigned to the EAA group (9 g/day) and 26 assigned to the placebo group (powdered lactose, 9 g/day) were available for analysis. Patients received EAA supplementation or a placebo from 1 week prior to surgery to 2 weeks after it. The rectus femoris muscle area was measured using ultrasonography and quadriceps muscle strength was measured isometrically with a handheld dynamometer, preoperatively and periodically up to 2 years postoperatively. Knee pain, knee range of motion, functional mobility, and Knee Society Score 2011 subjective scores were measured at each time point. Perioperative management, except for supplementation, was identical in the 2 groups. RESULTS: Taking the baseline as 100%, the mean values in the EAA and placebo groups were 134% ± 31% and 114% ± 27%, respectively, for the rectus femoris muscle area and 159% ± 54% and 125% ± 40% for the quadriceps muscle strength, respectively, at 2 years after surgery. The differences were significant (p < 0.05). Clinical outcomes were not significantly different between the 2 groups. CONCLUSIONS: Perioperative EAA supplementation contributes to the recovery of rectus femoris muscle volume and quadriceps muscle strength in the 2 years after TKA. The EAA supplementation did not impact clinical outcomes. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence. Copyright © 2023 by The Journal of Bone and Joint Surgery, Incorporated. DOI: 10.2106/JBJS.22.00675 PMID: 36856692 [Indexed for MEDLINE] Conflict of interest statement: Disclosure: The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJS/H362).

Efficacy and tolerability of a specific blend of amino acids in patients with anorexia nervosa treated in a hospital setting: study protocol for a randomized controlled trial.

12. Trials. 2023 Feb 9;24(1):104. doi: 10.1186/s13063-023-07120-7. Efficacy and tolerability of a specific blend of amino acids in patients with anorexia nervosa treated in a hospital setting: study protocol for a randomized controlled trial. Dalle Grave R(1), Calugi S(2), Ruocco C(3), Chimini M(2), Segala A(4), Ragni M(3), Carruba M(3), Valerio A(4), Nisoli E(3). Author information: (1)Department of Eating and Weight Disorders, Villa Garda Hospital, Via Monte Baldo, 89, Garda, 37016, Verona, Italy. rdalleg@gmail.com. (2)Department of Eating and Weight Disorders, Villa Garda Hospital, Via Monte Baldo, 89, Garda, 37016, Verona, Italy. (3)Center for Study and Research on Obesity, Department of Biomedical Technology and Translational Medicine, University of Milan, Via Vanvitelli, 32, 20129, Milan, Italy. (4)Department of Molecular and Translational Medicine, Brescia University, Viale Europa 11, 25123, Brescia, Italy. BACKGROUND: Specific blends of essential amino acids (EAA) containing a high percentage of branched-chain amino acids preserves mitochondrial metabolism and higher physical resistance in elderly mice, increasing their survival and improving physical performance and cognitive functions in malnourished elderly patients. However, no study has been yet done on patients with anorexia nervosa (AN) who regain weight with specialized intensive treatment. The present study aims to evaluate the efficacy of supplementation with EAA on the change in lean body mass (LBM) and other physical and psychological outcomes in patients with AN who are undergoing specialist treatment for eating disorders. METHODS: This is a 13-week randomized, double-blind, placebo-controlled study. Patients will be randomized to either a mixture of a complex blend of EAA and intermediates of the tricarboxylic acid (TCA) cycle (citrate, malate, succinate) supplementation (or placebo) upon admission at the intensive residential and day-hospital treatment for eating disorders. Ninety-two participants with AN aged 16-50 years will be recruited from a specialized intensive treatment of eating disorders. Double-blind assessment will be conducted at baseline (T0) and the end of the 13 weeks of treatment (T1). The study's primary aim is to evaluate the efficacy of supplementation with EAA and TCA intermediates on the change in lean body mass (LBM) with weight restoration in patients with AN who are undergoing specialist treatment for eating disorders. The secondary aims of the study are to assess the effect of dietary supplementation on physical fitness, weight restoration, modification of AN and general psychopathology, and psychosocial impairment. DISCUSSION: The study's results will inform researchers and clinicians on whether supplementing a mixture of EAA and TCA cycle intermediates will improve the increase of LBM and other important physical and psychological outcomes in patients with AN who regain weight with specialized intensive treatment. TRIAL REGISTRATION: NCT, NCT05290285. Registered on 22 March 2022. © 2023. The Author(s). DOI: 10.1186/s13063-023-07120-7 PMCID: PMC9912576 PMID: 36759873 [Indexed for MEDLINE] Conflict of interest statement: The authors declare that they have no competing interests.

Differential plasma protein expression after ingestion of essential amino acid-based dietary supplement verses whey protein in low physical functioning older adults.

13. Geroscience. 2023 Jun;45(3):1729-1743. doi: 10.1007/s11357-023-00725-5. Epub 2023 Feb 1. Differential plasma protein expression after ingestion of essential amino acid-based dietary supplement verses whey protein in low physical functioning older adults. Azhar G(1), Verma A(1), Zhang X(1), Pangle A(1), Patyal P(1), Zhang W(2), Che Y(1), Coker K(1), Wolfe RR(1), Wei JY(3). Author information: (1)Department of Geriatrics, Donald W. Reynolds Institute On Aging, University of Arkansas for Medical Sciences, 4301 West Markham, Little Rock, AR, 72205, USA. (2)Department of Mathematics and Statistics, University of Arkansas at Little Rock, Little Rock, AR, 72204, USA. (3)Department of Geriatrics, Donald W. Reynolds Institute On Aging, University of Arkansas for Medical Sciences, 4301 West Markham, Little Rock, AR, 72205, USA. WeiJeanne@uams.edu. Erratum in Geroscience. 2023 Jun;45(3):2087. doi: 10.1007/s11357-023-00751-3. In a recent randomized, double-blind, placebo-controlled trial, we were able to demonstrate the superiority of a dietary supplement composed of essential amino acids (EAAs) over whey protein, in older adults with low physical function. In this paper, we describe the comparative plasma protein expression in the same subject groups of EAAs vs whey. The plasma proteomics data was generated using SOMA scan assay. A total of twenty proteins were found to be differentially expressed in both groups with a 1.5-fold change. Notably, five proteins showed a significantly higher fold change expression in the EAA group which included adenylate kinase isoenzyme 1, casein kinase II 2-alpha, Nascent polypeptide-associated complex subunit alpha, peroxiredoxin-1, and peroxiredoxin-6. These five proteins might have played a significant role in providing energy for the improved cardiac and muscle strength of older adults with LPF. On the other hand, fifteen proteins showed slightly lower fold change expression in the EAA group. Some of these 15 proteins regulate metabolism and were found to be associated with inflammation or other comorbidities. Gene Ontology (GO) enrichment analysis showed the association of these proteins with several biological processes. Furthermore, protein-protein interaction network analysis also showed distinct networks between upregulated and downregulated proteins. In conclusion, the important biological roles of the upregulated proteins plus better physical function of participants in the EAAs vs whey group demonstrated that EAAs have the potential to improve muscle strength and physical function in older adults. This study was registered with ClinicalTrials.gov: NCT03424265 "Nutritional interventions in heart failure." © 2023. The Author(s). DOI: 10.1007/s11357-023-00725-5 PMCID: PMC10400527 PMID: 36720768 [Indexed for MEDLINE] Conflict of interest statement: R.R.W. and J.Y.W. are the inventors of the EAA-based composition tested in this protocol (U.S. Patent 9,597,367 B2). R.R.W. is a shareholder in Essential Blends, LLC, and The Amino Company, Inc. All other authors declare that they have no competing interests.

Essential Amino Acid Ingestion Facilitates Leucine Retention and Attenuates Myofibrillar Protein Breakdown following Bodyweight Resistance Exercise in Young Adults in a Home-Based Setting.

14. Nutrients. 2022 Aug 27;14(17):3532. doi: 10.3390/nu14173532. Essential Amino Acid Ingestion Facilitates Leucine Retention and Attenuates Myofibrillar Protein Breakdown following Bodyweight Resistance Exercise in Young Adults in a Home-Based Setting. Waskiw-Ford M(1), Hodson N(1), Fung HJW(1), West DWD(1)(2), Apong P(3), Bashir R(3), Moore DR(1). Author information: (1)Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON M5S 2C9, Canada. (2)KITE Research, Toronto Rehabilitation Institute, Toronto, ON M5G 2A2, Canada. (3)Iovate Health Sciences International, Toronto, ON L6M 2R7, Canada. Home-based resistance exercise (RE) has become increasingly prevalent, but its effects on protein metabolism are understudied. We tested the effect of an essential amino acid formulation (EAA+: 9 g EAAs, 3 g leucine) and branched-chain amino acids (BCAAs: 6 g BCAAs, 3 g leucine), relative to a carbohydrate (CHO) placebo, on exogenous leucine retention and myofibrillar protein breakdown following dynamic bodyweight RE in a home-based setting. Twelve recreationally active adults (nine male, three female) participated in a double-blind, placebo-controlled, crossover study with four trial conditions: (i) RE and EAA+ (EX-EAA+); (ii) RE and BCAAs (EX-BCAA); (iii) RE and CHO placebo (EX-CHO); and (iv) rest and CHO placebo (REST-CHO). Total exogenous leucine oxidation and retention (estimates of whole-body anabolism) and urinary 3-methylhistidine:creatinine ratio (3MH:Cr; estimate of muscle catabolism) were assessed over 5 h post-supplement. Total exogenous leucine oxidation and retention in EX-EAA+ and EX-BCAA did not significantly differ (p = 0.116) but were greater than EX-CHO (p < 0.01). There was a main effect of condition on urinary 3MH:Cr (p = 0.034), with post hoc analysis revealing a trend (p = 0.096) for reduced urinary 3MH:Cr with EX-EAA+ (32%) compared to EX-CHO. By direct comparison, urinary 3MH:Cr was significantly lower (23%) in EX-EAA+ than EX-BCAA (p = 0.026). In summary, the ingestion of EAA+ or BCAA provided leucine that was ~60% retained for protein synthesis following home-based bodyweight RE, but EAA+ most effectively attenuated myofibrillar protein breakdown. DOI: 10.3390/nu14173532 PMCID: PMC9460609 PMID: 36079790 [Indexed for MEDLINE] Conflict of interest statement: D.R.M. has received research funding from Iovate Health Sciences but declares no financial conflict of interest. P.A. and R.B. are employees of Iovate Health Sciences and developed the investigational supplements. P.A. and R.B. were not involved in data collection, analysis, interpretation of data, or the decision to publish the results but did review the final manuscript draft. All other authors have no conflicts to declare.

Continuous oral stable isotope ingestion to measure whole-body protein turnover.

15. Clin Nutr ESPEN. 2022 Jun;49:385-389. doi: 10.1016/j.clnesp.2022.03.017. Epub 2022 Mar 23. Continuous oral stable isotope ingestion to measure whole-body protein turnover. Hirsch KR(1), Church DD(2), Wolfe RR(3), Ferrando AA(3). Author information: (1)Department of Geriatrics, Donald W. Reynolds Institute on Aging, Center for Translational Research in Aging & Longevity, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA. Electronic address: krhirsch@uams.edu. (2)Department of Geriatrics, Donald W. Reynolds Institute on Aging, Center for Translational Research in Aging & Longevity, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA. Electronic address: DChurch@uams.edu. (3)Department of Geriatrics, Donald W. Reynolds Institute on Aging, Center for Translational Research in Aging & Longevity, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA. BACKGROUND & AIMS: Protein kinetic responses to nutrition and exercise interventions are commonly evaluated using a primed-constant infusion of stable isotope tracers. While this methodology is state-of-the-art, the required preparation at a certified pharmacy makes the utilization of isotope infusion both expensive and logistically cumbersome. Oral tracer ingestion has been used to quantify 24-h whole-body protein status; however, this does not permit examination of acute interventional effects. Ingestion of a priming bolus, followed by continuous ingestion of stable isotope tracer in a 'sip feeding' fashion may provide a more feasible alternative for quantifying acute kinetic responses. Therefore, the purpose of this study was to evaluate the viability of a primed continuous oral sip-ingestion method of stable isotope tracers for the evaluation of whole-body protein kinetics. METHODS: In a randomized, crossover design, eight healthy adults (63% female; Age: 29.4 ± 5.8 yrs; BMI: 24.3 ± 2.7 kg/m2) completed two, two-period stable isotope oral ingestion studies, consisting of a 3 h basal fasted period, followed by a 4-h post-ingestion period. After the basal period, subjects ingested either 6.3 g (Low) or 12.6 g (High) of an essential amino acid (EAA) enriched whey protein supplement. The continuous oral sip-feed method was initiated with a primed oral bolus dose of L-[ring-2H5]phenylalanine, L-[ring-2H2]tyrosine, and L-[ring-2H4]tyrosine, followed by oral sip doses of L-[ring-2H5]phenylalanine, L-[ring-2H2]tyrosine every 10 min to approximate steady state tracer enrichment. Blood samples were taken throughout the basal and post-meal periods to determine tracer enrichment. Whole-body net protein balance (NB), synthesis (PS), breakdown (PB), and exogenous hydroxylation were calculated for each period. Repeated measure ANOVAs (treatment × time) were used to assess differences in protein kinetics. RESULTS: Using the sip feed method, NB, PS, and hydroxylation were significantly increased with ingestion of protein (p < 0.05) during the postprandial period, regardless of amount of protein ingested; ΔNB from the postabsorptive to postprandial period was significantly greater for high compared to low protein (p = 0.026; low = 6.2 ± 5.1 g protein·240 min-1; high = 11.8 ± 3.9 g protein·240 min-1). CONCLUSION: The current study provides preliminary evidence that continuous oral sip-feeding of stable isotope tracer is a feasible method that provides physiologically relevant measures of protein metabolism. Assessments of variance and individual responses revealed high measurement variability with the sip-feed method compared to previously published constant infusion responses, but ΔNB, ΔPS, and ΔPB were comparable. In situations where constant infusion is not feasible, oral sip-feeding could be used as an alternative method for measurement of acute, postprandial protein metabolism. Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved. DOI: 10.1016/j.clnesp.2022.03.017 PMID: 35623841 [Indexed for MEDLINE] Conflict of interest statement: Declaration of competing interest RRW is the inventor of the pending patent application entitled “Composition for stimulating muscle growth, repair and maintenance”. Remaining authors declare that they have no competing interests.