Primary studies included in this systematic review

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Primary study

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

Journal Clinical nutrition (Edinburgh, Scotland)
Year 2012
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Cet article est inclus dans 1 Systematic review Systematic reviews (1 reference)

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

Primary study

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Effect of essential amino acid supplementation on quality of life, Amino acid profile and strength in institutionalized elderly patients.

Journal Clinical nutrition (Edinburgh, Scotland)
Year 2011
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Cet article est inclus dans 1 Systematic review Systematic reviews (1 reference)

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Summary: Background & aims: This study assessed the efficacy of supplemented essential amino acids on depressive symptoms, nutrition, muscle function, daily physical activity, and health-related quality of life (HRQoL) of institutionalized elderly patients. METHODS: Forty-one patients (58.5% women; mean age 79.8 yrs) with sequelae of coronary artery disease (73%), femoral fracture (34%), were randomly assigned to receive oral essential amino acids 4 gr 2 times a day for 8 weeks or isocaloric placebo. Before randomization and 8 weeks after the protocol started, the following variables were measured: depressive symptoms (Geriatric Depression Scale, GDS), nutritional panel (Mini Nutritional Assessment, MNA; serum albumin and prealbumin levels), muscle strength (Hand Grip, HG), Activity Daily Life (ADL), Quality of Life (SF-36, HRQoL) and amino acid profile. RESULTS: Compared with the placebo group, EAA patients improved nutrition (MNA score 22.6 ± 1.5 post vs 21.8 ± 1.6 pre; p < 0. 04, albumin g/dl 4.04 ± 0.35 post vs 3.88 ± 0.3 pre; p < 0.01), GDS(score 10.3 ± 1.75 post vs 13.85 ± 3.37 pre; p < 0.001), HG (Kg 19.75 ± 1.7 post vs 18.68 ± 1.36 pre; p = 0.001), ADL (p < 0.04) and both physical and mental components of SF-36 (p < 0.002). CONCLUSIONS: Oral supplementation with essential amino acids improved several determinants of quality of life in institutionalized elderly patients, including depressive symptoms, nutrition, muscle function and daily life activity.

Primary study

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EAA supplementation to increase nitrogen intake improves muscle function during bed rest in the elderly

Journal Clinical nutrition (Edinburgh, Scotland)
Year 2010
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Cet article est inclus dans 2 Systematic reviews Systematic reviews (2 references)

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Background & aims: Older individuals are more likely to experience extended hospitalization and become protein malnourished during hospitalization. The concomitant compulsory inactivity results in functional decline. Increasing protein intake in hospitalized patients improves nitrogen balance, but effects on function are unknown. In the present study, we examined the effects of increasing protein intake by essential amino acid (EAA) supplementation in older individuals subjected to 10. d bed rest on LBM and muscle function. Methods: Subjects were given a placebo (n=12, 68 ± 5 (SD) yrs, 83 ± 19 kg) or 15. g of EAA (n=10, 71 ± 6, 72 ± 8 kg) 3 times per day throughout 10. d of bed rest. LBM, muscle protein synthesis, and muscle function were determined before and after bed rest. Due to an imbalance in randomized gender distribution between groups, gender and beginning functional and LBM measures were utilized for analyses by repeated measures analysis of covariance (RMANCOVA). Results: Analyses revealed the potential for the preservation of functional outcomes with EAA supplementation. Conclusions: Increasing protein intake above the RDA may preserve muscle function in the elderly during compulsory inactivity. EAA supplementation is potentially an efficient method of increasing protein intake without affecting satiety. © 2009 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism.

Primary study

Unclassified

Comprehensive effects of supplemented essential amino acids in patients with severe COPD and sarcopenia.

Journal Monaldi archives for chest disease = Archivio Monaldi per le malattie del torace / Fondazione clinica del lavoro, IRCCS [and] Istituto di clinica tisiologica e malattie apparato respiratorio, Università di Napoli, Secondo ateneo
Year 2010
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Cet article est inclus dans 3 Systematic reviews Systematic reviews (3 references)

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AIM: Aim of the study was to investigate whether or not oral supplementation of essential amino acids (EAAs) may improve body composition, muscle metabolism, physical activity, cognitive function, and health status in a population of subjects with severe chronic obstructive pulmonary disease (COPD) and sarcopenia. METHODS: Thirty-two patients (25 males) (FEV1/FVC < 40% predicted), age 75 +/- 7 years, were randomised (n = 16 in both groups) to receive 4 gr/bid EAAs or placebo according to a double-blind design. When entered the study (T0), after four (T4), and after twelve (T12) weeks of treatments, body weight, fat free-mass (FFM), plasma lactate concentration (micromol/l), arterial PaCO2 and PaO2, physical activity (n degree steps/day), cognitive function (Mini Mental State Examination; MMSE), health status (St. George's Respiratory Questionnaire; SGRQ) were measured. RESULTS: EAAs supplemented, but not patients assuming placebo, progressively improved all baseline variables overtime. In particular, at T12 of EAAs supplementation, body weight (BW) increased by 6 Kg (p = 0.002), FFM by 3.6 Kg (p = 0.05), plasma lactate decreased from 1.6 micromol/l to 1.3 micromol/l (p = 0.023), PaO2 increased by 4.6 mmHg (p = 0.01), physical activity increased by 80% (p = 0.01). Moreover, the score for cognitive dysfunction improved from 19.1 scores to 20.8 (p = 0.011), while the SRGQ score also improved from 723 to 69.6 even though this trend did not reach the statistical significance. CONCLUSIONS. A three-month EAAs supplementation may have comprehensive effects on nutritional status; muscle energy metabolism; blood oxygen tension, physical autonomy; cognitive function, and perception of health status in patients with severe COPD and secondary sarcopenia.

Primary study

Unclassified

Long-term leucine supplementation does not increase muscle mass or strength in healthy elderly men

Journal The American journal of clinical nutrition
Year 2009
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Cet article est inclus dans 4 Systematic reviews Systematic reviews (4 references)

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Background: It has been reported that the blunted muscle protein synthetic response to food intake in the elderly can be normalized by increasing the leucine content of a meal. Objective: The objective was to assess the effect of 3 mo of leucine supplementation on muscle mass and strength in healthy elderly men. Design: Thirty healthy elderly men with a mean (6SEM) age of 71 ± 4 y and body mass index (BMI; in kg/m2) of 26.1 ± 0.5 were randomly assigned to either a placebo-supplemented (n = 15) or leucine-supplemented (n = 15) group. Leucine or placebo (2.5 g) was administered with each main meal during a 3-mo intervention period. Whole-body insulin sensitivity, muscle strength (one-repetition maximum), muscle mass (measured by computed tomography and dual-energy X-ray absorptiometry), myosin heavy chain isoform distribution, and plasma amino acid and lipid profiles were assessed before, during, and/or after the intervention period. Results: No changes in skeletal muscle mass or strength were observed over time in either the leucine- or placebo-supplemented group. No improvements in indexes of whole-body insulin sensitivity (oral glucose insulin sensitivity index and the homeostasis model assessment of insulin resistance), blood glycated hemoglobin content, or the plasma lipid profile were observed. Conclusion: Long-term leucine supplementation (7.5 g/d) does not augment skeletal muscle mass or strength and does not improve glycemic control or the blood lipid profile in healthy elderly men. This trial was registered at clinicaltrials.gov as NCT00807508. © 2009 American Society for Nutrition.

Primary study

Unclassified

Amino acid supplementation increases lean body mass, basal muscle protein synthesis, and insulin-like growth factor-I expression in older women

Journal The Journal of clinical endocrinology and metabolism
Year 2009
Liens Pubmed DOI PubMed Central

Cet article est inclus dans 5 Systematic reviews Systematic reviews (5 references)

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Context: Inadequate dietary protein intake has been implicated in sarcopenia. Objective and Design: The objectives of this study were to determine whether: 1) chronic essential amino acid (EAA) supplementation improves postabsorptive muscle protein fractional synthesis rate (FSR), lean body mass (LBM), and one-repetition maximum muscle strength, and androgen receptor and IGF-I muscle protein expression; and 2) the acute anabolic response to EAA ingestion is preserved after a 3-month supplementation period. Using a randomized, double-blinded, placebo-controlled design, older women (68 ± 2 yr) were assigned to receive either placebo (n = 7), or 15 g EAA/d [supplemented treatment group (SUP)] (n = 7) for 3 months. Metabolic outcomes were assessed in association with stable isotope studies conducted at 0 and 3 months. Setting: The study was performed at The University of Texas Medical Branch General Clinical Research Center. Results: Ingestion of 7.5 g EAA acutely stimulated FSR in both groups at 0 months (P < 0.05). Basal FSR at 3 months was increased in SUP only. The magnitude of the acute response to EAA was unaltered after 3 months in SUP. LBM increased in SUP only (P < 0.05). One-repetition maximum strength remained unchanged in both groups. Basal IGF-I protein expression increased in SUP after 3 months (P = 0.05), with no changes in androgen receptor or total and phosphorylated Akt, mammalian target of rapamycin, S6 kinase, and 4E-binding protein. Conclusions: EAA improved LBM and basal muscle protein synthesis in older individuals. The acute anabolic response to EAA supplementation is maintained over time and can improve LBM, possibly offsetting the debilitating effects of sarcopenia. Copyright © 2009 by The Endocrine Society.

Primary study

Unclassified

Effect of amino acid supplementation on muscle mass, strength and physical function in elderly.

Journal Clinical nutrition (Edinburgh, Scotland)
Year 2008
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Cet article est inclus dans 2 Systematic reviews Systematic reviews (2 references)

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BACKGROUND & AIMS: With advancing age there is a gradual decline in muscle mass, strength and function. The aim of this study was to determine if regular intake of a nutritional supplement containing essential amino acids (EAA)+arginine could reverse these responses in elderly subjects. METHODS: Twelve glucose intolerant subjects (67.0+/-5.6 (SD) years, 7 females, 5 males) ingested 11 g of EAA+arginine two times a day, between meals for 16 weeks. Diet and activity were not otherwise modified. Lean body mass (DEXA) was measured every fourth week. Maximal leg strength was tested and functional tests were performed at week 0, 8, 12, and 16. RESULTS: Lean body mass (LBM) increased during the study (p=0.038). At week 12, the average increase in LBM was 1.14+/-0.36 (SE) kg (p<0.05 vs baseline), whereas at week 16, the increase was 0.60+/-0.38 kg (NS vs baseline). The lower extremity strength measure score (sum of individual knee flexors and extensors' one repetition maximum, n=10) was 127.5+/-21.8 kg at baseline, and average increase during the study was 22.2+/-6.1% (p<0.001). Improvements were also observed in usual gait speed (p=0.002), timed 5-step test (p=0.007), and timed floor-transfer test (p=0.022). CONCLUSION: Supplementation of the diet with EAA+arginine improves lean body mass, strength and physical function compared to baseline values in glucose intolerant elderly individuals.

Primary study

Unclassified

Resistance training and timed essential amino acids protect against the loss of muscle mass and strength during 28 days of bed rest and energy deficit

Journal Journal of applied physiology (Bethesda, Md. : 1985)
Year 2008
Liens Pubmed DOI PubMed Central

Cet article est inclus dans 1 Systematic review Systematic reviews (1 reference)

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Spaceflight and bed rest (BR) result in losses of muscle mass and strength. Resistance training (RT) and amino acid (AA) supplementation are potential countermeasures to minimize these losses. However, it is unknown if timing of supplementation with exercise can optimize benefits, particularly with energy deficit. We examined the effect of these countermeasures on body composition, strength, and insulin levels in 31 men (ages 31-55 yr) during BR (28 days) followed by active recovery (14 days). Subjects were randomly assigned to essential AA supplementation (AA group, n = 7); RT with AA given 3 h after training (RT group, n = 12); or RT with AA given 5 min before training (AART group, n = 12). Energy intake was reduced by 8 ± 6%. Midthigh muscle area declined with BR for the AA > RT > AART groups: -11%, -3%, -4% (P = 0.05). Similarly, greatest losses in lower body muscle strength were seen in the AA group (-22%). These were attenuated in the exercising groups [RT (-8%) and AART (-6%; P < 0.05)]. Fat mass and midthigh intramuscular fat increased after BR in the AA group (+3% and +14%, respectively), and decreased in the RT (-5% and -4%) and AART groups (-1 and -5%; P = 0.05). Muscle mass and strength returned toward baseline after recovery, but the AA group showed the lowest regains. Combined resistance training with AA supplementation pre- or postexercise attenuated the losses in muscle mass and strength by approximately two-thirds compared with AA supplement alone during BR and energy deficit. These data support the efficacy of combined AA and RT as a countermeasure against muscle wasting due to low gravity.

Primary study

Unclassified

Adequate energy-protein intake is not enough to improve nutritional and metabolic status in muscle-depleted patients with chronic heart failure.

Journal European journal of heart failure
Year 2008
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Cet article est inclus dans 2 Systematic reviews Systematic reviews (2 references)

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BACKGROUND: An adequate energy-protein intake (EPI) when combined with amino acid supplementation may have a positive impact on nutritional and metabolic status in patients with chronic heart failure (CHF). METHODS AND RESULTS: Thirty eight stable CHF patients (27 males, 73.5+/-4 years; BMI 22.5+/-1.4 kg/m2), with severe depletion of muscle mass and were randomised to oral supplements of essential amino acids 8 g/day (EAA group; n=21) or no supplements (controls; n=17). All patients had adequate EPI (energy> or =30 kcal/kg; proteins >1.1 g/kg). At baseline and 2-months after randomisation, the patients underwent metabolic (plasma lactate, pyruvate concentration; serum insulin level; estimate of insulin resistance by HOMA index), nutritional (measure of nitrogen balance), and functional (exercise test, walking test) evaluations. Body weight increased by >1 kg in 80% of supplemented patients (mean 2.96 kg) and in 30% of controls (mean 2.3 kg) (interaction <0.05). Changes in arm muscle area, nitrogen balance, and HOMA index were similar between the two treatment groups. Plasma lactate and pyruvate levels increased in controls (p<0.01 for both) but decreased in the supplemented group (p<0.01 and 0.02 respectively). EAA supplemented patients but not controls improved both exercise output and peak oxygen consumption and walking test. CONCLUSIONS: Adequate EPI when combined with essential amino acid supplementation may improve nutritional and metabolic status in most muscle-depleted CHF patients.

Primary study

Unclassified

Supplementation of soy protein with branched-chain amino acids alters protein metabolism in healthy elderly and even more in patients with chronic obstructive pulmonary disease.

Journal The American journal of clinical nutrition
Year 2007
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Cet article est inclus dans 1 Systematic review Systematic reviews (1 reference)

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BACKGROUND: It is often suggested that chronic wasting diseases [eg, chronic obstructive pulmonary disease (COPD)] may benefit from branched-chain amino acid (BCAA) administration via improved protein metabolism. OBJECTIVE: The aim was to examine whether adding BCAAs to a soy protein meal would enhance protein anabolism in COPD patients and in healthy elderly persons. DESIGN: Eight normal-weight COPD patients and 8 healthy control subjects were examined on 2 test days. Simultaneous continuous intravenous infusion of l-[ring-(2)H(5)]phenylalanine (Phe) and l-[ring-(2)H(2)]tyrosine tracers was done postabsorptively and at 2 h of ingestion of a maltodextrin soy or maltodextrin soy + BCAA protein meal (rate of ingestion: 0.02 g protein.kg body weight(-1).20 min(-1)) in a crossover design. Together with the meal, oral ingestion of 1-[(13)C]Phe was performed to measure first-pass Phe splanchnic extraction (SPE(Phe)). The endogenous rate of Phe appearance [reflecting whole-body protein breakdown (WbPB)], whole-body protein synthesis (WbPS), and net WbPS (WbPS - WbPB) were calculated. Arterialized venous blood was sampled for amino acid enrichment and concentration analyses. RESULTS: Soy feeding induced a reduction in WbPB and an increase in WbPS. BCAA supplementation of soy protein resulted in a significantly higher (P < 0.05) increase in WbPS than did soy protein alone in COPD patients but not in the healthy elderly. BCAA supplementation did not significantly alter the change in WbPB or net WbPS. Furthermore, BCAA supplementation decreased (absolute) SPE(Phe) (P < 0.05) but did not change the percentage Phe hydroxylation in the splanchnic area, which indicates a BCAA-related reduction in splanchnic protein synthesis. CONCLUSION: BCAA supplementation to soy protein enhances WbPS in patients with COPD and alters interorgan protein metabolism in favor of the peripheral (muscle) compartment in healthy elderly and even more in COPD patients.