Research
L-Leucine
102 peer-reviewed studies curated from PubMed and Semantic Scholar.
Studies
Sorted by quality and recency
Effects of Leucine Supplementation in Older Adults with Sarcopenia: A Meta-Analysis.
Meta-analysis of leucine supplementation in older adults with sarcopenia, including 10 RCTs and 1 prospective study with 1133 participants. Leucine supplementation showed significant improvements in handgrip strength, appendicular skeletal muscle mass/height, and gait speed, especially at high dosages and when combined with vitamin D.
Enhancing Muscle Quality: Exploring Leucine and Whey Protein in Sarcopenic Individuals.
This systematic review analyzed literature on leucine-enriched whey protein supplementation combined with resistance training in older adults with sarcopenia. The intervention showed favorable outcomes in increasing lean muscle mass, muscle strength, and physical performance. The review discusses the anabolic properties of leucine and its potential synergistic effects with resistance exercise.
Meta-analysis of the effects of supplemental leucine alone or in combination with other branched-chain amino acids on lactational performance in dairy cows and the associated influencing factors.
Meta-analysis of 17 studies on the effects of leucine (Leu) alone or in combination with isoleucine and valine (ILV) on lactational performance in dairy cows. Leu supplementation increased milk protein concentration, and ILV supplementation tended to increase milk protein yield. The positive effects were more prominent with specific dietary conditions and supplementation methods.
Association of leucine and other branched chain amino acids with clinical outcomes in malnourished inpatients: a secondary analysis of the randomized clinical trial EFFORT.
Secondary analysis of the EFFORT trial investigating the impact of leucine, isoleucine, and valine metabolism on clinical outcomes in malnourished inpatients. Low serum leucine levels were associated with a doubled risk of 180-day all-cause mortality. Similar associations were found for isoleucine and valine. Nutritional support did not significantly affect mortality based on metabolite levels.
[Effect of dietary supplements and whey protein on muscle mass and strength of the operated limb after anterior cruciate ligament reconstruction: a systematic review].
Systematic review of 6 RCTs with 186 patients evaluating dietary supplements on muscle mass and strength after ACL reconstruction. Leucine showed a significant increase in thigh circumference, but no supplements had a statistically significant effect on muscle strength.
Association of postprandial postexercise muscle protein synthesis rates with dietary leucine: A systematic review.
Systematic review examining the association of dietary leucine with postprandial postexercise muscle protein synthesis (MPS) rates. Leucine dose was associated with MPS response in older adults, but not in younger adults. No plasma leucine variable predicted MPS rates effectively.
The Effect of Leucine Supplementation on Sarcopenia-Related Measures in Older Adults: A Systematic Review and Meta-Analysis of 17 Randomized Controlled Trials.
Systematic review and meta-analysis of 17 RCTs with 1418 subjects examining leucine supplementation on sarcopenia-related measures in older adults. Leucine-isolated supplementation showed no effect on muscle mass and strength, but leucine combined with vitamin D improved handgrip strength and gait speed.
Effect of supplementation with leucine alone, with other nutrients or with physical exercise in older people with sarcopenia: a systematic review.
Systematic review of intervention studies on leucine supplementation in older adults with sarcopenia. Leucine alone did not improve sarcopenic markers, but leucine paired with protein supplements showed promise in improving sarcopenic markers, with or without physical exercise.
Evaluating the Leucine Trigger Hypothesis to Explain the Post-prandial Regulation of Muscle Protein Synthesis in Young and Older Adults: A Systematic Review.
This systematic review evaluates the leucine trigger hypothesis for post-prandial regulation of muscle protein synthesis (MPS) in young and older adults. It finds mixed evidence, with 16 out of 29 studies supporting the hypothesis, particularly in older adults and with isolated protein sources.
Effects of leucine-rich protein supplements on anthropometric parameter and muscle strength in the elderly: a systematic review and meta-analysis.
Systematic review and meta-analysis of 16 studies with 999 elderly subjects examining leucine supplementation effects. Leucine significantly increased body weight, lean body mass, and BMI, especially in sarcopenic individuals, but did not significantly affect muscle strength.
Oral amino acid tracer delivery detects feeding and exercise changes in myofibrillar protein synthesis rates in male adults.
The study investigated the efficacy of oral administration of leucine and phenylalanine tracers to measure myofibrillar protein synthesis rates in response to feeding and exercise. Participants were randomized into rested-fasted, rested-fed, or exercise-fed conditions. Results showed that myofibrillar protein synthesis rates were greater in the exercise-fed and rested-fed conditions compared to the fasted condition, indicating the potential of oral essential amino acid tracers as an alternative method for studying muscle protein synthesis.
Anti-sarcopenic effect of leucine-enriched branched-chain amino acid supplementation among elderly chronic kidney disease patients: a double-blinded randomized controlled trial.
A double-blinded RCT evaluated the effects of leucine-enriched BCAA supplementation on muscle mass in elderly CKD patients. The leucine group showed a significant increase in lean muscle mass compared to placebo, but no significant differences in muscle strength or biomarkers of muscle activity.
The efficacy and safety of leucine-enriched essential amino acids in knee osteoarthritis patients: A randomized controlled trial.
RCT evaluating the efficacy and safety of 12g daily leucine-enriched essential amino acids supplementation in 65 knee osteoarthritis patients over 8 weeks. The experimental group showed significant improvements in muscle density and quality of life compared to controls, with no significant safety concerns.
A Randomized Controlled Trial on the Effects of Leucine-Supplement Combined with Nutritional Counseling on Body Composition in Mix Cancer Older Men.
RCT evaluating the effect of leucine supplementation combined with nutritional counseling on body composition in older men with gastrointestinal tract cancer. The leucine group showed significant gains in body weight and lean mass, though no significant intergroup differences were detected.
Effectiveness of a Novel Food Composed of Leucine, Omega-3 Fatty Acids and Probiotic Lactobacillus paracasei PS23 for the Treatment of Sarcopenia in Elderly Subjects: A 2-Month Randomized Double-Blind Placebo-Controlled Trial
This randomized clinical trial evaluated the effectiveness of a food composed of omega-3 fatty acids, leucine, and probiotic Lactobacillus paracasei PS23 on sarcopenic patients over 2 months. The intervention group showed significant improvements in appendicular lean mass, muscle performance, and amino acid profiles compared to the placebo group.
Does supplementation with leucine-enriched protein alone and in combination with fish-oil-derived n-3 PUFA affect muscle mass, strength, physical performance, and muscle protein synthesis in well-nourished older adults? A randomized, double-blind, placebo-controlled trial.
This 24-week randomized, double-blind, placebo-controlled trial investigated the effects of leucine-enriched protein (LEU-PRO) alone and combined with n-3 PUFAs on muscle mass, strength, and physical performance in 107 older adults at risk of sarcopenia. The study found no beneficial effects on appendicular lean mass, strength, physical performance, or muscle protein synthesis. However, some metabolic markers were affected by the supplementation.
L-leucine improves anemia and growth in patients with transfusion-dependent Diamond-Blackfan anemia: Results from a multicenter pilot phase I/II study from the Diamond-Blackfan Anemia Registry.
This multicenter phase I/II study evaluated the safety and efficacy of L-leucine in 55 transfusion-dependent patients with Diamond-Blackfan anemia. L-leucine was found to be safe, with 16% of subjects showing an erythroid response and improvements in weight and growth velocity observed in 36% and 44% of evaluable subjects, respectively.
Effects of Leucine Administration in Sarcopenia: A Randomized and Placebo-controlled Clinical Trial.
RCT of 50 older individuals assessing the efficacy of leucine administration (6 g/day) versus placebo over 13 weeks. Leucine improved functional performance and lean mass index in sarcopenia, and enhanced respiratory muscle function. No significant effects on cognitive function, nutritional assessment, or inflammatory markers were observed.
Beneficial Effects of Leucine Supplementation on Criteria for Sarcopenia: A Systematic Review.
Systematic review of 23 studies on leucine supplementation for sarcopenia in older individuals. Leucine or leucine-enriched proteins significantly improve lean muscle-mass content and show mixed results for muscular strength. Effects on physical performance are less studied. Promising results are noted for post-stroke rehabilitation and liver cirrhosis.
Does L-leucine supplementation cause any effect on glucose homeostasis in rodent models of glucose intolerance? A systematic review.
Systematic review of 34 studies on L-leucine supplementation in glucose-intolerant rodent models. L-leucine improved metabolic markers in diet-induced obesity models when offered during the development of the metabolic disorder, but not after. Branched-chain amino acid supplementation was effective in streptozotocin-induced β-cells death but not in DIO models.
The effectiveness of leucine on muscle protein synthesis, lean body mass and leg lean mass accretion in older people: a systematic review and meta-analysis.
This meta-analysis assessed the effect of leucine supplementation on muscle protein synthesis and lean mass in elderly individuals. Leucine significantly increased the muscle protein fractional synthetic rate but showed no significant effect on lean body mass or leg lean mass.
Leucine and Sildenafil Combination Therapy Reduces Body Weight and Metformin Enhances the Effect at Low Dose: A Randomized Controlled Trial.
This 24-week randomized controlled trial evaluated the effect of leucine combined with sildenafil and metformin on weight loss in 267 participants with a BMI of 30-45 kg/m2. The combination of leucine, metformin, and sildenafil resulted in significant placebo-adjusted mean bodyweight reductions, with the Leu/Met/Sil 1.0 group showing the most robust weight loss, particularly in African Americans and individuals with BMI 30-39.9 kg/m2.
Acute L-Leucine Supplementation and Sprint Exercise Elicit Distinct Appetite and Inflammatory Responses in Persons with Overweight: A Randomized, Counterbalanced, and Crossover Design Study.
This randomized, counterbalanced, and crossover study evaluated the acute effects of L-leucine supplementation and high-intensity sprint exercise on appetite-controlling neuropeptides, subjective perception of appetite, satiety, food intake, and inflammatory response in 12 sedentary overweight adult men. L-leucine decreased subjective perception of appetite, while exercise and L-leucine together influenced inflammatory markers and appetite control.
High leucine branched-chain amino acids supplementation ameliorates quadriceps femoris muscle thickness reduction and attenuates interleukin-6 in critically ill patients: A randomised controlled trial.
This RCT examined the effects of high leucine BCAA supplementation on muscle thickness and IL-6 levels in critically ill patients. The BCAA group showed less muscle thickness reduction and a significant reduction in IL-6 levels compared to the control group.
Unraveling the transcriptomic effects of leucine supplementation on muscle growth and performance in basketball athletes.
RCT with 20 basketball players assessing the effects of leucine supplementation on exercise performance and muscle growth. Leucine significantly improved 282-foot sprint performance and showed trends of improvement in other metrics. Transcriptomic analysis revealed differentially expressed genes related to immune response and muscle growth, with qPCR validation supporting these findings.
Effects of Combined Intragastric Administration of Quinine with L-Leucine or L-Isoleucine on the Glycemic Response to, and Gastric Emptying of, a Mixed-Nutrient Drink in Healthy Males.
RCT investigating the effects of combined intragastric administration of quinine with L-leucine or L-isoleucine on glycemic response and gastric emptying in healthy males. The combination delayed the early rise in plasma glucose and stimulated insulin compared to individual components, but did not affect gastric emptying.
Leucine requirement determined in healthy young adult males using the indicator amino acid oxidation method.
The study used the indicator amino acid oxidation method to determine the leucine requirement in healthy young adult males. The mean leucine requirement was found to be 33.6 mg⋅kg⋅d, with higher intakes associated with increased plasma leucine and decreased valine, isoleucine, and serine concentrations.
The impact of leucine supplementation on body composition and glucose tolerance following energy restriction: an 8-week RCT in adults at risk of the metabolic syndrome.
An 8-week RCT in 37 adults at risk of metabolic syndrome examined the effects of leucine supplementation during energy restriction. Leucine supplementation resulted in greater preservation of fat-free mass and lean tissue mass, particularly in men, but did not impact glucose metabolism.
Effects of L-Leucine Supplementation and Resistance Training on Adipokine Markers in Untrained Perimenopausal and Postmenopausal Women.
This study examined the effects of 5 g of leucine supplementation compared with a placebo during a 10-week resistance training program on body composition and adipokine concentrations in untrained perimenopausal and postmenopausal women. Significant group differences were found in visfatin and leptin concentrations, with visfatin higher in the placebo group and leptin higher in the leucine group. Both groups showed decreases in adiponectin concentrations, and MCP-1 decreased only in the placebo group.
High-protein diet with excess leucine prevents inactivity-induced insulin resistance in women.
RCT testing a high-protein BCAA-enriched diet's ability to prevent insulin resistance during long-term bed rest in healthy women. The high protein-BCAA diet prevented inactivity-induced insulin resistance, while the conventional diet did not.
Leucine Supplementation Increases Muscle Strength and Volume, Reduces Inflammation, and Affects Wellbeing in Adults and Adolescents with Cerebral Palsy.
RCT of leucine supplementation in 21 adolescents and adults with cerebral palsy over 10 weeks. The leucine group showed a 25.4% increase in muscle strength, a 3.6% increase in muscle volume, a 59.1% reduction in CRP, and improved perceptions of wellbeing compared to the control group.
Dileucine ingestion is more effective than leucine in stimulating muscle protein turnover in young males: a double blind randomized controlled trial.
This double-blind randomized controlled trial investigated the effects of dileucine and leucine ingestion on muscle protein turnover in 10 healthy young men. Dileucine ingestion increased plasma dileucine concentrations and stimulated muscle protein synthesis rates, enhancing muscle protein turnover. Leucine ingestion did not stimulate an increase in muscle protein turnover.
Modulation of Energy Sensing by Leucine Synergy with Natural Sirtuin Activators: Effects on Health Span.
The study investigated the effects of leucine combined with resveratrol on energy sensing and healthspan. In a 4-week placebo-controlled trial with 36 prediabetic subjects, the combination reduced insulin resistance and improved glucose dynamics. Preclinical studies showed increased Sirt1 activity and lifespan, and reduced atherosclerotic lesions in mice.
Efficacy of L-Leucine Supplementation Coupled with a Calorie-Restricted Diet to Promote Weight Loss in Mid-Life Women.
RCT evaluating the effect of leucine supplementation with a calorie-restricted diet in 34 mid-life overweight and obese women over 12 weeks. Both groups lost weight, but no significant difference in body composition or RMR was found between groups. A greater proportion of women in the leucine group gained or maintained lean mass, though not statistically significant.
Leucine Supplementation Has No Further Effect on Training-induced Muscle Adaptations.
RCT of 25 resistance-trained men assessing the impact of 10 g leucine supplementation on muscle mass and strength during a 12-week resistance training program. Leucine supplementation did not enhance gains in muscle strength and mass compared to placebo.
Countering disuse atrophy in older adults with low-volume leucine supplementation.
RCT of leucine supplementation in older adults during a 7-day bed rest protocol followed by 5 days of rehabilitation. Leucine reduced the loss of leg lean mass but had limited impact on strength or endurance-based functional outcomes. It did not affect markers of anabolic signaling or protein degradation.
Leucine-Enriched Essential Amino Acids Improve Recovery from Post-Exercise Muscle Damage Independent of Increases in Integrated Myofibrillar Protein Synthesis in Young Men.
RCT of 20 recreationally active males supplemented with leucine-enriched essential amino acids (LEAAs) or placebo for four days post-exercise. LEAAs moderately attenuated muscle damage and improved recovery without increasing myofibrillar protein synthesis compared to placebo.
Leucine supplementation attenuates macrophage foam-cell formation: Studies in humans, mice, and cultured macrophages.
The study investigated the role of leucine supplementation in macrophage lipid metabolism across humans, mice, and cultured macrophages. Leucine supplementation decreased cellular cholesterol mass, inhibited cholesterol biosynthesis, increased cholesterol efflux, and improved mitochondrial respiration and ATP production, highlighting its protective role in attenuating macrophage foam-cell formation.
Effects of Whey, Soy or Leucine Supplementation with 12 Weeks of Resistance Training on Strength, Body Composition, and Skeletal Muscle and Adipose Tissue Histological Attributes in College-Aged Males.
RCT of 75 untrained, college-aged males examining the effects of L-leucine or protein supplements standardized to leucine on body composition, strength, and muscle/adipose tissue attributes over 12 weeks of resistance training. All groups, including placebo, showed similar increases in muscle mass and strength. Whey protein groups showed increased satellite cell counts, suggesting potential long-term benefits.
Dietary leucine supplementation alters energy metabolism and induces slow-to-fast transitions in longissimus dorsi muscle of weanling piglets.
The study investigated the effects of dietary leucine supplementation on energy metabolism and muscle fiber transitions in the longissimus dorsi muscle of weanling piglets. It found that a high-leucine diet suppressed oxidative phosphorylation and fatty acid β-oxidation while activating glycolysis, and promoted slow-to-fast muscle fiber transitions.
Activation of mammalian target of rapamycin signaling in skeletal muscle of neonatal chicks: effects of dietary leucine and age.
The study investigated the effects of dietary leucine and age on mTOR signaling in chick pectoral muscles. Dietary leucine increased mTOR, S6K1, and 4E-BP1 mRNA expression and phosphorylation, stimulating muscle protein synthesis in neonatal chicks, but this effect was attenuated with aging.
Prolonged leucine supplementation does not augment muscle mass or affect glycemic control in elderly type 2 diabetic men.
RCT of 60 elderly males with type 2 diabetes assessing the effects of 6 months of leucine supplementation (7.5 g/d) on body composition, muscle mass, strength, and glycemic control. The study found no significant changes in lean tissue mass, muscle strength, or glycemic control between the leucine and placebo groups.
Stimulation of muscle anabolism by resistance exercise and ingestion of leucine plus protein.
RCT investigating the effect of additional leucine with whey protein on muscle anabolism in untrained subjects performing resistance exercise. The study found that while amino acid concentrations increased with leucine and whey protein ingestion, the anabolic response was not greater than that of whey protein alone.
A high proportion of leucine is required for optimal stimulation of the rate of muscle protein synthesis by essential amino acids in the elderly.
This study evaluated the effects of enriching an essential amino acid mixture with leucine on muscle protein metabolism in elderly and young individuals. Results showed that increasing leucine proportion in EAAs improved muscle protein synthesis in the elderly but did not further stimulate synthesis in young subjects.
Effects of a leucine-enriched amino acid supplement on muscle mass, muscle strength, and physical function in post-stroke patients with sarcopenia: A randomized controlled trial.
This randomized controlled trial investigated the effects of a leucine-enriched amino acid supplement on muscle mass, muscle strength, and physical function in 44 post-stroke patients with sarcopenia. The intervention group showed significantly greater improvements in physical function, handgrip strength, and skeletal muscle mass index compared to the control group over an eight-week period.
Efficacy of L-leucine Supplementation Coupled With Resistance Training in Untrained Midlife Women.
This randomized, double-blind, placebo-controlled trial investigated the effects of leucine supplementation with resistance training in untrained peri- and postmenopausal women. The study found no significant changes in fat free mass or serum hormones due to leucine supplementation, although both groups showed significant increases in strength from resistance training alone.
The Effects of Leucine-Enriched Branched-Chain Amino Acid Supplementation on Recovery After High-Intensity Resistance Exercise.
RCT with 22 recreationally active subjects comparing BCAA, leucine-enriched BCAA (LBCAA), and standalone leucine (LEU) supplementation on recovery after high-intensity resistance exercise. LEU showed decreased power and increased soreness and creatine kinase levels, indicating it was less effective for recovery compared to BCAA.
Leucine Supplementation Does Not Alter Insulin Sensitivity in Prefrail and Frail Older Women following a Resistance Training Protocol.
Double-blinded placebo-controlled study on the effects of leucine supplementation and resistance training on insulin sensitivity in prefrail and frail older women. No significant effects on insulin sensitivity were observed, although total lean body mass increased and percentage body fat decreased for both groups.
Leucine-enriched essential amino acid supplementation in mechanically ventilated trauma patients: a feasibility study.
A feasibility study assessing the administration of a leucine-enriched essential amino acid supplement to mechanically ventilated trauma patients in ICU. The study faced significant barriers to recruitment and measurement of outcomes, indicating the need for careful design in future trials.
Protein leucine content is a determinant of shorter- and longer-term muscle protein synthetic responses at rest and following resistance exercise in healthy older women: a randomized, controlled trial.
RCT in healthy older women comparing the effects of a high-leucine protein beverage to a mixed protein beverage on muscle protein synthesis. The leucine-enriched beverage induced greater increases in both acute and integrated muscle protein synthesis, suggesting potential benefits for maintaining muscle mass.
Leucine, Not Total Protein, Content of a Supplement Is the Primary Determinant of Muscle Protein Anabolic Responses in Healthy Older Women.
RCT comparing the effects of leucine-enriched milk protein versus whey protein isolate on muscle protein synthesis in healthy older women. Both supplements increased myofibrillar protein synthesis, with leucine showing a greater effect in the exercised leg.
Lower Fasted-State but Greater Increase in Muscle Protein Synthesis in Response to Elevated Plasma Amino Acids in Obesity.
The study compared muscle protein synthesis in adults with obesity and lean controls in the fasted state and during an amino acid infusion using L-[2,3,3,4,5,5,5,6,6,6-H]leucine. Obese subjects had lower fasted-state muscle protein synthesis but showed a greater increase in muscle protein synthesis during amino acid infusion compared to lean controls.
Effect of Mixed Meal and Leucine Intake on Plasma Amino Acid Concentrations in Young Men.
Randomized crossover study in 10 healthy young men investigating the effect of a mixed meal and free amino acids intake on plasma leucine concentrations. The study found that rapid elevations in plasma leucine concentrations are suppressed when leucine is ingested at the same time as a meal, suggesting the timing of intake is important for maximizing the anabolic response.
Novel essential amino acid supplements enriched with L-leucine facilitate increased protein and energy intakes in older women: a randomised controlled trial.
RCT in older women testing bars and gels enriched with essential amino acids, including L-leucine, to facilitate protein and energy intake. Supplementation increased total energy intake, suggesting a nutritional strategy for addressing deficiencies in older women.
Human skeletal muscle is refractory to the anabolic effects of leucine during the postprandial muscle-full period in older men.
RCT investigating the effects of leucine supplementation on muscle protein synthesis (MPS) and anabolic signaling in older men. The study found that leucine top-up after essential amino acid feeding did not enhance MPS during the postprandial period, suggesting muscle refractoriness to nutrient-led anabolic stimulation.
Dietary Leucine Supplementation Decreases Whole-Body Protein Turnover before, but Not during, Immune System Stimulation in Pigs.
The study investigated the effect of dietary leucine supplementation on whole-body protein turnover in pigs before and during immune system stimulation (ISS). Results showed that leucine reduced whole-body protein synthesis and degradation before ISS but had no effect during ISS.
Leucine supplementation enhances integrative myofibrillar protein synthesis in free-living older men consuming lower- and higher-protein diets: a parallel-group crossover study.
A parallel-group crossover study in 20 healthy older men examined the impact of leucine co-ingestion with meals on myofibrillar protein synthesis (MyoPS). Leucine supplementation enhanced MyoPS in both rested and resistance exercise conditions, regardless of whether participants consumed lower or higher protein diets.
Enriching a protein drink with leucine augments muscle protein synthesis after resistance exercise in young and older men.
RCT investigating the effect of leucine-enriched protein drink on muscle protein synthesis after resistance exercise in young and older men. Leucine supplementation improved anabolic responses compared to alanine, enhancing muscle protein synthesis in both age groups.
l-Leucine Increases Skeletal Muscle IGF-1 but Does Not Differentially Increase Akt/mTORC1 Signaling and Serum IGF-1 Compared to Ursolic Acid in Response to Resistance Exercise in Resistance-Trained Men.
RCT with 9 resistance-trained men examining the effects of l-leucine and ursolic acid ingestion post-resistance exercise. L-leucine increased skeletal muscle IGF-1 concentration but did not affect Akt/mTORC1 signaling or serum IGF-1 compared to placebo and ursolic acid.
Activation of mTORC1 by leucine is potentiated by branched-chain amino acids and even more so by essential amino acids following resistance exercise.
RCT with eight trained volunteers comparing the effects of leucine, BCAA, and EAA ingestion on anabolic signaling following resistance exercise. EAA ingestion stimulated translation initiation more effectively than leucine or BCAA, with a ninefold increase in S6K1 activity in the EAA trial.
Determination of the safety of leucine supplementation in healthy elderly men.
The study assessed the safety of leucine supplementation in six healthy elderly men, with intakes ranging from 50 to 750 mg/kg/day. Blood ammonia concentrations above normal values were observed at intakes >550 mg/kg/day. Leucine oxidation plateaued after 450 mg/kg/day, suggesting an upper intake limit similar to young men at 500 mg/kg/day.
Co-ingestion of carbohydrate with branched-chain amino acids or L-leucine does not preferentially increase serum IGF-1 and expression of myogenic-related genes in response to a single bout of resistance exercise.
RCT with 41 college-age males examining the effects of co-ingesting carbohydrate with BCAA or L-leucine on serum IGF-1 and myogenic gene expression after resistance exercise. Serum IGF-1 was greater in the CHO + BCAA group compared to placebo, but not affected by resistance exercise. Significant time effects were noted for cyclin B1 and p21cip expression.
Double-blind, placebo-controlled pilot trial of L-Leucine-enriched amino-acid mixtures on body composition and physical performance in men and women aged 65-75 years.
Double-blind, placebo-controlled pilot trial of L-Leucine-enriched amino-acid mixtures on body composition and physical performance in elderly men and women. Supplementation with EAAs containing 20% or 40% L-Leucine improved functional performance and lean tissue mass, with significant gains in specific physical tests.
Effects of free leucine supplementation and resistance training on muscle strength and functional status in older adults: a randomized controlled trial.
RCT assessing the effect of 10 g/day leucine supplementation combined with resistance training versus resistance training only on muscle strength and functional status in older adults. Clinically significant gains in isometric leg strength and functional status were observed in the leucine group compared to control.
Leucine partially protects muscle mass and function during bed rest in middle-aged adults.
RCT assessing leucine supplementation in middle-aged adults during 14 days of bed rest. Leucine partially protected muscle mass and function, maintaining knee extensor peak torque and endurance, and reducing lean mass loss compared to control.
Intake of low-dose leucine-rich essential amino acids stimulates muscle anabolism equivalently to bolus whey protein in older women at rest and after exercise.
RCT comparing the effects of bolus whey protein and low-dose leucine-enriched essential amino acids on muscle protein synthesis in older women. Both interventions stimulated muscle protein synthesis similarly at rest and after exercise, with no significant advantage of whey protein over leucine-enriched amino acids.
Metabolic and molecular responses to leucine-enriched branched chain amino acid supplementation in the skeletal muscle of alcoholic cirrhosis.
Prospective study on the effects of leucine-enriched branched chain amino acid supplementation in alcoholic cirrhosis patients. The study found that impaired mTOR1 signaling and increased autophagy in skeletal muscle were acutely reversed by BCAA/LEU supplementation.
Protein-leucine ingestion activates a regenerative inflammo-myogenic transcriptome in skeletal muscle following intense endurance exercise.
In a randomized single-blind triple-crossover study, 12 trained men ingested protein-leucine supplements after intense cycling. The study found that protein-leucine ingestion modulated inflammatory and myogenic transcriptome responses, enhancing skeletal muscle recovery and adaptation post-exercise.
Protein-leucine fed dose effects on muscle protein synthesis after endurance exercise.
This study investigated the effects of protein-leucine ingestion on muscle protein synthesis after endurance exercise in 12 trained men. The ingestion of 23 g of protein with 5 g of leucine achieved near-maximal muscle protein synthesis, suggesting benefits for recovery and performance.
Randomized pilot study: effects of an exercise programme and leucine supplementation in patients with cirrhosis.
Randomized pilot study of 17 outpatients with cirrhosis evaluating the effects of an exercise programme and leucine supplementation. The exercise group showed improved exercise capacity, increased lower thigh circumference, and enhanced HRQoL, with no complications of cirrhosis observed.
Leucine-enriched amino acid ingestion after resistance exercise prolongs myofibrillar protein synthesis and amino acid transporter expression in older men.
RCT investigating the effects of leucine-enriched amino acid ingestion on myofibrillar protein synthesis and amino acid transporter expression in older men post-resistance exercise. Leucine-enriched ingestion prolonged the anabolic response and increased amino acid transporter expression at 24 hours compared to control.
Leucine supplementation of a low-protein mixed macronutrient beverage enhances myofibrillar protein synthesis in young men: a double-blind, randomized trial.
Double-blind, randomized trial assessing the effect of leucine supplementation in a low-protein beverage on myofibrillar protein synthesis (MPS) in young men. The study found that a low-protein beverage supplemented with a high amount of leucine (5.0 g) was as effective as a high-protein dose at stimulating increased MPS rates.
Effect of leucine supplementation on fat free mass with prolonged hypoxic exposure during a 13-day trek to Everest Base Camp: a double-blind randomized study.
Double-blind randomized study of leucine supplementation on fat-free mass during a 13-day trek to Everest Base Camp. Despite significant loss of body weight, FFM, and fat mass during high altitude exposure, leucine did not attenuate FFM loss compared to control.
Hydrolyzed casein and whey protein meals comparably stimulate net whole-body protein synthesis in COPD patients with nutritional depletion without an additional effect of leucine co-ingestion.
RCT in 12 COPD patients with nutritional depletion comparing hydrolyzed casein and whey protein meals on whole-body protein synthesis. Both protein meals comparably stimulated net protein synthesis, with no additional effect from leucine co-ingestion.
Rehabilitation and leucine supplementation as possible contributors to an athlete's muscle strength in the reathletization phase following anterior cruciate ligament surgery.
Double-blind RCT with 45 athletes post-ACL surgery comparing leucine supplementation to placebo during a rehabilitation program. Both groups improved muscle strength and reduced fat mass, but the leucine group showed a significant positive result in thigh muscle perimeter at 10cm from the patella.
Supplementation of a suboptimal protein dose with leucine or essential amino acids: effects on myofibrillar protein synthesis at rest and following resistance exercise in men.
RCT examining the effects of leucine and essential amino acids supplementation on myofibrillar protein synthesis (MPS) in 24 males following resistance exercise. Leucine and essential amino acids were as effective as whey protein in stimulating postprandial MPS, but only whey protein sustained increased MPS rates post-exercise.
Leucine co-ingestion improves post-prandial muscle protein accretion in elderly men.
RCT investigating the impact of leucine co-ingestion on muscle protein accretion in elderly men. Leucine co-ingestion with dietary protein increased muscle protein synthesis rates compared to protein alone.
A protein-leucine supplement increases branched-chain amino acid and nitrogen turnover but not performance.
This double-blind, randomized, crossover study investigated the effects of a protein-leucine supplement on high-intensity endurance performance and metabolism in 12 male cyclists. The supplement increased BCAA levels and nitrogen turnover but had no significant effect on sprint power, although it reduced serum creatine kinase concentration, indicating reduced tissue damage.
An enteral leucine supply modulates human duodenal mucosal proteome and decreases the expression of enzymes involved in fatty acid beta-oxidation.
RCT with 5 healthy volunteers receiving enteral leucine infusion to study its effects on the duodenal mucosal proteome. Leucine supplementation altered the expression of enzymes involved in lipid metabolism, suggesting a slowdown in fatty acid beta-oxidation.
Daily L-leucine supplementation in novice trainees during a 12-week weight training program.
RCT investigating the effects of daily oral L-leucine ingestion on strength and body composition during a 12-week resistance-training program in 26 initially untrained men. The leucine group showed significantly higher gains in total 5-RM strength compared to the placebo group, but no significant differences in lean tissue mass or fat mass changes.
Muscle protein synthesis in cancer patients can be stimulated with a specially formulated medical food.
RCT in 25 cancer patients comparing a specially formulated medical food high in leucine and protein to a conventional medical food. The experimental group showed increased muscle protein synthesis, while the control group did not, indicating that leucine-enriched supplements can stimulate muscle protein synthesis in cancer patients.
Excess leucine intake enhances muscle anabolic signaling but not net protein anabolism in young men and women.
RCT examining the effect of different leucine concentrations on muscle protein turnover in young men and women. While arterial leucine concentration and delivery increased with higher leucine intake, muscle protein synthesis increased similarly in both groups. Muscle protein breakdown decreased only in the higher leucine group, but net muscle protein balance was similar. Leucine may influence autophagy regulation.
Effects of leucine or whey protein addition to an oral glucose solution on serum insulin, plasma glucose and plasma amino acid responses in horses at rest and following exercise.
RCT in six mature Thoroughbreds testing the effects of leucine or whey protein addition to a glucose solution on serum insulin, plasma glucose, and amino acid responses at rest and following exercise. Leucine, but not whey protein, significantly augmented the serum insulin response to an oral glucose load, suggesting potential for increasing post-exercise muscle glycogen synthesis.
Long-term leucine supplementation does not increase muscle mass or strength in healthy elderly men.
RCT of 30 healthy elderly men assessing the effect of 3 months of leucine supplementation on muscle mass and strength. No changes in skeletal muscle mass, strength, insulin sensitivity, or plasma lipid profile were observed in the leucine-supplemented group compared to placebo.
Leucine-enriched essential amino acid and carbohydrate ingestion following resistance exercise enhances mTOR signaling and protein synthesis in human muscle.
RCT with 16 male subjects examining the effects of leucine-enriched essential amino acids and carbohydrates (EAA+CHO) ingestion post-resistance exercise. The study found that EAA+CHO ingestion enhanced mTOR signaling and muscle protein synthesis compared to control, suggesting a role in improved muscle protein synthesis post-exercise.
Leucine supplementation improves muscle protein synthesis in elderly men independently of hyperaminoacidaemia.
The study assessed the effects of dietary leucine supplementation on muscle protein synthesis in elderly men. Twenty healthy male subjects were given a balanced diet with or without leucine supplementation. Muscle protein synthesis was significantly greater in the leucine-supplemented group compared to the control group, indicating that leucine supplementation improves muscle protein synthesis independently of other amino acids.
Co-ingestion of protein and leucine stimulates muscle protein synthesis rates to the same extent in young and elderly lean men.
RCT involving 8 elderly and 8 young lean men to assess the effects of carbohydrate with or without protein and free leucine on whole-body protein balance and muscle protein synthesis rates. Co-ingestion of protein and leucine with carbohydrate improved protein balance and increased muscle protein synthesis rates similarly in both age groups.
Effects of increasing insulin secretion on acute postexercise blood glucose disposal.
RCT with 14 male athletes examining the effects of carbohydrate, casein protein hydrolysate, and leucine ingestion on insulin levels and plasma glucose disposal during postexercise recovery. The combined ingestion of protein hydrolysate and/or leucine with carbohydrate increased insulin secretion but did not affect plasma glucose disposal in the first 3.5 hours of recovery.
Effects of dietary leucine supplementation on exercise performance.
This study investigated the effects of dietary leucine supplementation on exercise performance in 13 competitive outrigger canoeists. Leucine supplementation significantly improved endurance performance and upper body power compared to placebo, without affecting the plasma tryptophan to BCAA ratio, heart rate, or anthropometric variables.
Leucine supplementation does not enhance acute strength or running performance but affects serum amino acid concentration.
RCT examining the effect of leucine supplementation on serum amino acid concentration and physical performance in competitive male power athletes. Leucine supplementation increased serum leucine levels but did not enhance acute strength or running performance.
A controlled trial of amino acid therapy in amyotrophic lateral sclerosis: I. Clinical, functional, and maximum isometric torque data.
Double-blind, placebo-controlled trial of BCAA and L-threonine in 95 ALS patients over six months. BCAA group gained weight, but both BCAA and L-threonine groups showed greater decline in forced vital capacity compared to placebo. No significant differences in muscle strength or functional measures. Amino acids were well tolerated, but no beneficial effect on ALS disease course was observed.
Measurement of protein synthesis in human skeletal muscle: further investigation of the flooding technique.
The study measured protein synthesis rates in human quadriceps muscle using L-[1-13C]leucine and L-[1-13C]phenylalanine. The flooding technique showed higher synthesis rates compared to continuous infusion, but the increase was not attributed to stimulation by leucine. Protein synthesis rates were consistent across different amino acids and methods.
A comparison of the effects of intravenous infusion of individual branched-chain amino acids on blood amino acid levels in man.
Intravenous infusions of L-valine, L-isoleucine, L-leucine, and a mixture of branched-chain amino acids were administered to healthy volunteers. Leucine infusion resulted in significant decreases in tyrosine, phenylalanine, methionine, valine, and isoleucine concentrations, with increased insulin levels. The mixture of branched-chain amino acids showed similar effects to leucine alone.
To investigate the thermodynamic parameters of Li, Na and K salt of L leucinate at various temperature and concentration by conductometric measurement
Conductometric measurement of aqueous solutions of Li, Na, and K salts of L-leucine at different temperatures and concentrations to investigate solute-solvent and ion-solvent interactions. Thermodynamic parameters such as change in free energy, entropy, and enthalpy were studied.
Improvement of solubility and dissolution rate of Biopharmaceutical Class II drug atorvastatin calcium by using an essential amino acid L-leucine
The study aimed to enhance the solubility and dissolution rate of atorvastatin calcium using L-Leucine as a solubilizing agent through different solid dispersion methods. L-Leucine significantly improved the solubility and dissolution profile of atorvastatin calcium, with the solvent evaporation method showing the best results.
Muscle protein synthetic responses to exercise: effects of age, volume, and intensity.
The study explored the effects of resistance exercise volume and intensity on muscle myofibrillar protein synthesis (MPS) in young and older men. It found that doubling exercise volume increased MPS and p70S6 kinase phosphorylation in older men, suggesting that increased exercise volume is beneficial for maximizing postexercise MPS in aging.
Leucine supplementation and serum amino acids, testosterone, cortisol and growth hormone in male power athletes during training.
Randomised double-blind cross-over study on 20 male power athletes examining leucine supplementation effects during 10 weeks of training. Leucine supplementation prevented the decrease in serum leucine concentration, while serum testosterone increased initially and then decreased, and cortisol increased during the first 5 weeks.
The imbalance of brain large-chain aminoacid availability in amyotrophic lateral sclerosis patients treated with high doses of branched-chain aminoacids.
RCT assessing plasma concentrations of large neutral amino acids and glutamic acid in 24 amyotrophic lateral sclerosis patients receiving placebo or branched-chain amino acids, 15 untreated patients, and 15 healthy volunteers. Branched-chain amino acid plasma concentrations increased significantly in the treated group. Glutamic acid concentrations were higher in ALS patients than in healthy individuals. The study suggests an impairment of brain large neutral amino acid availability might contribute to symptom progression in ALS patients.
The separate and combined effect of leucine and insulin on muscle free amino acids.
The study investigated the separate and combined effects of leucine and insulin on muscle and plasma amino acid concentrations in 11 volunteers. Leucine infusion increased free leucine concentration in muscle and plasma, while decreasing other amino acids. Glucose infusion alone decreased essential amino acids, and the combination of leucine and glucose augmented these decreases, suggesting a specific effect of leucine on BCAA and a reduction in muscle proteolysis.
Measurement of the rate of protein synthesis in muscle of postabsorptive young men by injection of a 'flooding dose' of [1-13C]leucine.
The study used the 'flooding dose' technique to measure the rate of protein synthesis in muscle of postabsorptive young men by injecting [1-13C]leucine. The mean rate of muscle protein synthesis in 10 subjects was determined to be 1.95% per day.