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Home > Anti-aging Research > L-Leucine


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News & Research:

  • Ideal protein to help seniors rebuild lost muscle - Science Daily, 10/10/18 - "Researchers found that protein did not stop lean muscle loss caused by inactivity, however, whey supplements helped to rebuild muscle once the participants activities resumed ... whey versus collagen protein ... Whey is considered a high-quality or complete protein, meaning it is rich in all essential amino acids and is higher in leucine, one of the essential amino acids the body cannot make itself and therefore, must derive from food ... Collagen peptides, by comparison, are much lower in their leucine content, lack or are low in essential amino acids ... While protein was ineffective in mitigating muscle loss, say researchers, when participants returned to normal, muscle-building activity, the whey group recovered more skeletal muscle" - See whey protein at Amazon.com and leucine products at Amazon.com.
  • Eating protein three times a day could make our seniors stronger - Science Daily, 8/30/17 - "We observed that participants of both sexes who consumed protein in a balanced way during the day had more muscle strength than those who consumed more during the evening meal and less at breakfast. However, the distribution of protein throughout the day was not associated with their mobility ... All body tissues, including the muscles, are composed of proteins, which consist of amino acids. If the protein intake decreases, the synthesis is not done correctly and this leads to a loss of muscle mass ... "Our research is based on scientific evidence demonstrating that older people need to consume more protein per meal because they need a greater boost of amino acids for protein synthesis," says Dr. Chevalier, adding that one of the essential amino acids known for protein renewal is leucine" - See BulkSupplements Pure L-Leucine Powder (1 Kilogram).
  • Recommended daily protein intake too low for the elderly - Science Daily, 5/23/17 - "The RDA you will find on the nutrition labels on your food, however, were set in 1968, and the ones used by researchers and professionals were set in 2003. A recent review published in Frontiers in Nutrition points out that both these values do not do justice to the protein needs of the elderly and critically ill ... A big disservice is being done. The prescribed 0.8 g/kg/day just isn't enough protein for the elderly and people with a clinical condition .... he points out that the quality of proteins should be considered when setting the RDA guidelines and recommending protein supplements. He argues that there should be a stronger focus on leucine; an indispensable amino acid and building block for proteins. The elderly have a higher need for leucine to build muscle proteins, and milk-based proteins (e.g. milk and whey) are a good source for this"
  • Scientists identify amino acid that stops seizures in mice: Finding suggests novel mechanism for treating epilepsy - Science Daily, 6/19/15 - "researchers pre-treated mice with the amino acid L-leucine and another one, called D-leucine, which has a nearly identical structure to L-leucine and is essentially its biochemical mirror image ... When researchers induced seizures with shock therapy, animals pre-treated with either amino acid fared better, developing seizures at notably higher electric currents than mice that received placebo, a sign of greater seizure resistance ... L-leucine failed to abort ongoing seizures, while D-leucine effectively interrupted convulsions" - See leucine products at Amazon.com and Core Nutritionals Hmb Dietary Supplement, 90 Gram.  I doubt if you'll find the "D" form.  However, my mother had epilepsy so I'm very familiar with it and it doesn't make sense that you could give someone a supplement while they are having a seizure.
  • Prevalence of and interventions for sarcopenia in ageing adults: a systematic review. Report of the International Sarcopenia Initiative (EWGSOP and IWGS) - oxfordjournals.org - 9/21/14 - "EAAs (with 2.5 g of leucine) and HMB seem to have some effects on muscle mass and muscle function that need to be confirmed in larger trials" - [Nutra USA]
  • Leucine supplements boost muscle synthesis by 33% during exercise - Nutra USA, 10/6/11 - "In contrast with resistance exercise, sustained endurance exercise is mainly catabolic, yielding simultaneous reductions in muscle protein synthesis and plasma leucine concentrations during exercise, which may be attributed to the metabolic demand for branched chain amino acids in exercising skeletal muscle ... the leucine-enriched beverage was associated with a 33% increase in muscle protein synthesis ... Our findings indicate that increasing the leucine content of protein supplements provided for those populations susceptible to muscle loss, including proteolytic conditions—such as cachexia, sarcopenia, and calorie deprivation—may warrant further exploration" - [Abstract]
  • Research from Everest: Can leucine help burn fat and spare muscle tissue during exercise? - Science Daily, 8/28/11 - "Research on Mt. Everest climbers is adding to the evidence that an amino acid called leucine -- found in foods, dietary supplements, energy bars and other products -- may help people burn fat during periods of food restriction, such as climbing at high altitude, while keeping their muscle tissue ... We knew that leucine has been shown to help people on very low-calorie, or so-called 'calorie-restricted diets', stay healthy at sea level ... the findings also could help people at lower altitudes who want to lose weight while preserving their lean body mass, or who are elderly and don't eat or exercise enough to maintain their strength"
  • Dietary leucine may fight pre-diabetes, metabolic syndrome: Study shows improvements in animals with amino acid in diet - Science Daily, 6/22/11 - "mice who had been on a high-fat diet and who also received twice the usual intake of leucine, an amino acid found in protein, showed reductions in their prediabetic conditions with lower blood sugars and less fat in their livers, two of the collection of medical problems associated with insulin resistance that make up what is known as metabolic syndrome ... Their glucose tolerance tests improved ... Their bodies responded to insulin better than they would have before they got the leucine. It improved their ability to metabolize sugar and fats. It markedly improved their pre-diabetic condition. Their metabolic syndrome also improved"
  • Amino acid supplement makes mice live longer - Science Daily, 10/5/10 - "leucine, isoleucine, and valine extend the life span of single-celled yeast ... Animals that were given the extra amino acids over a period of months lived longer, with a median life span of 869 days compared to 774 days for untreated control animals, the researchers report. That's an increase of 12 percent ... The findings in older mice suggest that the supplementary mixture may be specifically beneficial for those who are elderly or ill" - See BCAA products at Amazon.com, it contains the three of these.
  • Leucine supplements could help prevent muscle loss - Nutra USA, 12/8/05
  • Feeling Old? Supplement Diet With Leucine Prevents Muscle Loss Linked To Aging - Science Daily, 12/4/05 - "After the age of 40, humans start loosing muscle at around 0.5-2% per year ... adding leucine to the diet restored a balanced metabolism"


  • Dietary leucine and fish oil cooperatively regulate skeletal myofiber type transformation via the CaMKII signaling pathway of pigs - Food Funct 2022 Dec 16. - "In conclusion, this study demonstrated that dietary Leu and FO co-regulated the transformation from glycolytic to oxidative skeletal myofiber type. It is hypothesized that there is an interaction between amino acids and polyunsaturated fatty acids, possibly via the CaMKII signaling pathway to upregulate MEF2 and mitochondrial biogenesis" - See leucine products at Amazon.com and omega-3 supplements at Amazon.com.
    • Mitochondrial Biogenesis - Science Direct - "Mitochondrial biogenesis is a major adaption of skeletal muscle to exercise training and is induced by a complex interplay between numerous signaling pathways that respond to metabolic, mechanical, and hypoxic stresses that are generated within the myocyte during contraction."
  • De-Training Effects Following Leucine-Enriched Whey Protein Supplementation and Resistance Training in Older Adults with Sarcopenia: A Randomized Controlled Trial with 24 Weeks of Follow-Up - J Nutr Health Aging 2022;26(11):994-1002 - "The study included older adults aged ≥ 65 years who were screened for sarcopenia at the Care Center from, a community in Hyogo, Japan. The participants were randomly allocated to one of three groups: whey protein supplementation after resistance training (RT + PRO; n = 27), resistance training only (RT; n = 27), and whey protein supplementation only (PRO; n = 27) ... We demonstrated that combined intervention of RT and PRO showed long-term maintenance in treating sarcopenia than RT only at 24 weeks after de-training. Therefore, PRO intake after RT may be useful in the treatment of sarcopenia in older adults" - See leucine products at Amazon.com and whey protein at Amazon.com.
  • Liver autophagy-induced valine and leucine in plasma reflect the metabolic effect of sodium glucose co-transporter 2 inhibitor dapagliflozin - EBioMedicine 2022 Nov 21 - "Sodium glucose co-transporter 2 (SGLT2) inhibitors are anti-diabetic drugs for type 2 diabetes that lower blood glucose levels and body weight. It is of special interest that SGLT2 inhibitors also improve liver metabolism and fatty liver. Liver is an important organ in regulation of energy metabolism, but the metabolic action of SGLT inhibitors in liver remains unclear ... Clinical study found that valine and leucine levels were markedly higher in patients treated with dapagliflozin (valine: P < 0·05 vs. control, leucine: P < 0·01 vs. control) than those not treated after one week intervention ... Dapagliflozin improves liver metabolism via hepatic autophagy, and plasma valine and leucine levels may reflect its metabolic effect" - See dapagliflozin at reliablerxpharmacy.com.
  • Leucine Supplementation in Middle-Aged Male Mice Improved Aging-Induced Vascular Remodeling and Dysfunction via Activating the Sirt1-Foxo1 Axis - Nutrients 2022 Sep 17 - "Vascular aging is associated with metabolic remodeling, and most studies focused on fatty acid and glucose metabolism. Based on our metabolomic data, leucine was significantly reduced in the aortas of aged mice. Whether leucine supplementation can reverse aging-induced vascular remodeling remains unknown ... Compared with the 21-month-old mice without leucine, leucine supplementation from 15 months significantly improved vascular relaxation, maintained the contractile phenotype of VSMCs, and repressed vascular inflammation and ROS levels. These benefits were not observed in the mice supplemented with leucine starting from 18 months, which was likely due to the reduction in leucine transporters Slc3a2 or Slc7a5 at 18 months. Furthermore, we found benefits from leucine via activating the Sirt1-induced Foxo1 deacetylation. Our findings indicated that leucine supplementation in middle-aged mice improved aging-induced vascular remodeling and dysfunction"
  • Leucine intake and risk of impaired physical function and frailty in older adults - J Gerontol A Biol Sci Med Sci 2022 Sep 15 - "Leucine is suggested to play a central role in age-related physical decline, but the effect of dietary leucine intake on physical functioning is uncertain. We examined the prospective association between dietary leucine intake and impaired lower-extremity function (ILEF) and frailty in older adults ... Higher leucine intake was associated with reduced risk of ILEF and frailty. Dietary leucine, obtained from foods rich in high-quality protein, could be a key nutrient to prevent age-related physical function decline in older adults"
  • Whey Protein, Leucine- and Vitamin-D-Enriched Oral Nutritional Supplementation for the Treatment of Sarcopenia - Nutrients 2022 Apr 6 - "The purpose of this review is to collate and describe all of the relevant efficacy studies carried out with a muscle-targeted oral nutritional supplementation (MT-ONS)-namely a whey-protein-based, leucine- and vitamin D-enriched formula aimed at optimizing their intake and satisfying their requirements-in different patient populations and clinical settings in order to determine if there is enough evidence to recommend prescription for the treatment of sarcopenia or its prevention in high-risk patient populations ... Consistent results have been observed in various clinical settings (community, rehabilitation centers, care homes), with or without adjunctive physical exercise programs. A positive effect on markers of inflammation has also been shown. A muscle-protein-sparing effect, with benefits on physical performance and function, has also been demonstrated in patients at risk of losing skeletal muscle mass (three trials), such as older patients undergoing weight loss or intensive rehabilitation programs associated with neurological disability (Parkinson's disease). MT-ONS has demonstrated not only a significant efficacy in clinical variables, but also a positive impact on healthcare resource consumption in the rehabilitation setting (length of stay and duration of rehabilitation)" - See whey protein at Amazon.com, leucine products at Amazon.com and vitamin D at Amazon.com.
  • Daily Leucine Intake Is Positively Associated with Lower Limb Skeletal Muscle Mass and Strength in the Elderly - Nutrients 2021, 13(10), 3536 - "Higher daily protein intake, with an emphasis on leucine content, is thought to mitigate age-related anabolic resistance, potentially counteracting age-related morphological and functional declines ... total daily leucine intake is associated with muscle mass and strength in healthy older individuals and this association remains after controlling for multiple factors, including overall protein intake. Furthermore, our breakpoint analysis revealed non-linearities and a potential threshold for habitual leucine intake, which may help guide future research on the effects of chronic leucine intake in age-related muscle loss" - [Nutra USA]
  • Leucine-enriched whey protein supplementation, resistance-based exercise, and cardiometabolic health in older adults: a randomized controlled trial - J Cachexia Sarcopenia Muscle 2021 Sep 14 - "Increasing protein intake (above the Recommended Dietary Amount) alone or with resistance-based exercise is suggested to improve cardiometabolic health ... Sixteen weeks of leucine-enriched whey protein supplementation alone and combined with resistance-based exercise improved cardiometabolic health markers in older adults" - See leucine products at Amazon.com and leucine at iHerb and whey protein at Amazon.com and iHerb.
  • Metformin and leucine increase satellite cells and collagen remo - FASEB J 2021 Sep;35(9):e21862 - "Loss of muscle mass and strength after disuse followed by impaired muscle recovery commonly occurs with aging. Metformin (MET) and leucine (LEU) individually have shown positive effects in skeletal muscle during atrophy conditions but have not been evaluated in combination nor tested as a remedy to enhance muscle recovery following disuse atrophy in aging ... Together, the dual treatment of MET and LEU was able to increase muscle function, satellite cell content, and reduce collagen accumulation, thus improving muscle quality during disuse and recovery in aging" - See metformin at ReliableRX and leucine products at Amazon.com and leucine at iHerb.
  • Leucine induces cardioprotection in vitro by promoting mitochondrial function via mTOR and Opa-1 signaling - Nutr Metab Cardiovasc Dis 2021 Jul 10 - "Coronary heart disease is a major global health concern. Further, severity of this condition is greatly influenced by myocardial ischemia/reperfusion (I/R) injury. Branched-chain amino acids (BCAAs) have cardioprotective effects against I/R via mammalian target of rapamycin (mTOR) activity, wherein Leu is considered to particularly regulate mTOR activation ... Leu treatment is critical in rendering a cardioprotective effect exhibited by BCAAs via mTOR signaling"
  • Higher Branched-Chain Amino Acid Intake Is Associated with Handgrip Strength among Korean Older Adults - Nutrients 2021 Apr 30 - "Sarcopenia is a disease of old age characterized by decreased muscle mass and strength. Branched-chain amino acids (BCAAs) promote muscle mass synthesis and increase muscle strength. We aimed to develop a dietary amino acid database and to examine the association between BCAA intake and handgrip strength in Korean older adults ... Grains greatly contributed to amino acid intake; however, a significant negative association was observed between handgrip strength and increased BCAA intake through grains. In the fully adjusted model, leucine intake and handgrip strength showed a positive association. Thus, consuming BCAAs (especially leucine) via a variety of food sources can help maintain muscle health in older people"
  • Dietary leucine requirement of older men and women is higher than current recommendations - Am J Clin Nutr 2020 Dec 16 - "Current national (34 mg . kg-1 . d-1) and international (39 mg kg-1 . d-1) recommendations for leucine in older adults are based on data from young adults. Evidence suggests that the leucine requirements of older adults are higher than those of young adults ... The mean leucine requirement for male participants was 77.8 mg . kg-1 . d-1 (upper 95% CI: 81.0) and for female participants, it was 78.2 mg . kg-1 . d-1 (upper 95% CI: 82.0) with no sex effect based on body weight. The data were therefore combined to yield a mean of 78.5 mg . kg-1 d-1 (upper 95% CI: 81.0 mg . kg-1 . d-1 ) for both sexes. On the basis of fat-free mass, the mean ± SEM leucine requirements were 115 ± 3.2 and 127 ± 2.4 mg . kg-1 . d-1 for male and female participants, respectively (P < 0.005) ... The estimated leucine requirement of older adults is more than double the amount in current recommendations. These data suggest that leucine could be a limiting amino acid in the diet of older adults consuming the current RDA for protein and those consuming a plant-based diet. In view of the functional and structural role of leucine, especially its importance in muscle protein synthesis, current leucine recommendations of older adults should be revised" - Note: 170 pounds is 77 KG. 77 KG times 115 mg = 8,855 mg or about 9 grams by my calculations. One scoop of the leucine I take contains 5 grams.
  • The Effect of Leucine-Enriched Essential Amino Acid Supplementation on Anabolic and Catabolic Signaling in Human Skeletal Muscle after Acute Resistance Exercise: A Randomized, Double-Blind, Placebo-Controlled, Parallel-Group Comparison Trial - Nutrients 2020 Aug 12 - "These data indicated that LEAA supplementation augments the effect of resistance exercise by enhancing mTORC1 signal activation after exercise"
  • Leucine Supplementation: A Novel Strategy for Modulating Lipid Metabolism and Energy Homeostasis - Nutrients. 2020 May 2 - "Lipid metabolism is an important and complex biochemical process involved in the storage of energy and maintenance of normal biological functions. Leucine, a branched amino acid, has anti-obesity effects on glucose tolerance, lipid metabolism, and insulin sensitivity. Leucine also modulates mitochondrial dysfunction, representing a new strategy to target aging, neurodegenerative disease, obesity, diabetes, and cardiovascular disease. Although various studies have been carried out, much uncertainty still exists and further studies are required to fully elucidate the relationship between leucine and lipid metabolism. This review offers an up-to-date report on leucine, as key roles in both lipid metabolism and energy homeostasis in vivo and in vitro by acceleration of fatty acid oxidation, lipolysis, activation of the adenosine 5'-monophosphate-activated protein kinase (AMPK)-silent information regulator of transcription 1 (SIRT1)-proliferator-activated receptor γ coactivator-1α (PGC-1α) pathway, synthesis, and/or secretion of adipokines and stability of the gut microbiota" - See leucine products at Amazon.com.
  • Leucine, Not Total Protein, Content of a Supplement Is the Primary Determinant of Muscle Protein Anabolic Responses in Healthy Older Women - J Nutr. 2018 Jul 1;148(7):1088-1095 - "Evidence suggests that this anabolic resistance can be overcome by consuming greater quantities of leucine ... whey protein isolate (WPI) ... randomly assigned with the use of a single-blind, parallel-group design to twice-daily consumption of either WPI [25 g WPI (3 g l-leucine)] or leucine (LEU; 10 g milk protein with 3 g total l-leucine) for 6 d ... A lower-protein (10 compared with 25 g/dose), leucine-matched beverage induced similar increases in acute and integrated myoPS in healthy older women. Lower-protein supplements with added leucine may represent an advantageous approach in older adults to maintain skeletal muscle anabolic sensitivity and attenuate muscle loss"
  • Effect of a leucine-enriched essential amino acids mixture on muscle recovery - J Phys Ther Sci. 2019 Jan;31(1):95-101 - "leucine-enriched essential amino acid mixture (LEAA) ... LEAA consumption suppressed exercise-induced elevation of muscle damage markers in blood, which suggests that LEAA could attenuate muscle damage and aid muscle recovery" - [Nutra USA] -Note:  I drink a protein mixture that includes leucine every day.  It tastes really bad.  If you can't take it, go with the capsules but then you have to take a ridiculous amount of tablets plus it's expensive doing it that way.  The casein shake I take after that gets some of the taste out of my mouth.
  • 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 - Nutrition. 2018 Jul 11;58:1-6 - "The intervention group (n = 21) received a leucine-enriched amino acid supplement; the control group (n = 23) did not. Both groups performed low-intensity resistance training in addition to a post-stroke rehabilitation program. A primary outcome of physical function by using the motor domain of Functional Independence Measure (FIM), and secondary outcomes of appendicular muscle mass (skeletal muscle mass index [SMI]) measured via bioelectrical impedance analysis and muscle strength as handgrip strength were measured at baseline and at the end of the intervention ... The FIM score increased significantly in both groups over time (P < 0.01), with significantly greater improvement in the intervention group than in the control group (P < 0.045). Handgrip strength also increased significantly over time (P <0.05), with significantly greater improvement in the intervention group (P < 0.01). The SMI increased significantly in the intervention group but not in the control group over time, with significantly greater improvement in the intervention group" - [Nutra USA]
  • Effect of Mixed Meal and Leucine Intake on Plasma Amino Acid Concentrations in Young Men - Nutrients 2018, 10(10), 1543 - "10 healthy young men (age 25 ± 1 years, height 1.73 ± 0.02 m, weight 65.8 ± 1.5 kg) underwent tests under different conditions—intake of 2 g of leucine (LEU), intake of a mixed meal (protein 27.5 g, including 2.15 g of leucine, protein: fat: carbohydrate ratio—22:25:53) only (MEAL), intake of 2 g of leucine immediately after a mixed meal (MEAL-LEU) and intake of 2 g of leucine 180 min after a mixed meal (MEAL-LEU180). Blood samples were collected within 420 min (240 min for LEU only) after intake and changes in amino acid concentrations were evaluated. Although the maximum plasma leucine concentration increased to 442 ± 24 µM for LEU, it was lower at 347 ± 16 µM (p < 0.05 vs. LEU) for MEAL-LEU, 205 ± 8 µM (p < 0.05 vs. LEU) for MEAL. The maximum plasma leucine concentration for MEAL-LEU180 increased to 481 ± 27 µM and compared to LEU there was no significant difference (p > 0.1). The observation that rapid elevations in plasma leucine concentrations are suppressed when leucine is ingested at the same time as a meal suggests that the timing of its intake must be considered to maximize the anabolic response" - [Nutra USA] - See leucine products at Amazon.com.
  • An Update on Protein, Leucine, Omega-3 Fatty Acids, and Vitamin D in the Prevention and Treatment of Sarcopenia and Functional Decline - Nutrients. 2018 Aug 16;10(8) - "Recent evidence supports a higher protein intake recommendation of 1.0⁻1.2 g/kg/day in healthy older adults; an evenly distributed mealtime protein intake or minimal protein per meal may be beneficial. In addition, vitamin D supplementation of 800⁻1000 IU, particularly when vitamin D status is low, and doses of ~3 g/day of n-3 PUFA may be favorable for physical function, muscle mass, and strength. Reviewed studies are highly heterogenous, yet the quantity, quality, and timing of intakes should be considered when designing intervention studies. Combined protein, leucine, vitamin D, and n-3 PUFA supplements may convey added benefits and may represent an intervention strategy in the prevention of sarcopenia and functional decline" - See leucine products at Amazon.com.
  • 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 - Am J Clin Nutr. 2018 Feb 1;107(2):217-226 - "Older women may not be consuming enough protein to maintain muscle mass. Augmentation of protein intake with leucine may enhance the muscle protein synthetic response in older women to aid in maintaining muscle mass ... healthy older women (aged 65-75 y, n = 11/group) consumed a fixed, weight-maintaining diet with protein at 1.0 g · kg-1 · d-1 and were randomly assigned to twice-daily consumption of either 15 g milk protein beverage containing 4.2 g leucine (LEU) or 15 g mixed protein (milk and soy) beverage containing 1.3 g leucine (CON) ... Acute myoPS increased in response to feeding in the rested (CON: 13% ± 4%; LEU: 53% ± 5%) and exercised (CON: 30% ± 4%; LEU: 87% ± 7%) leg in both groups, but the increase was greater in LEU (P < 0.001). Integrated myoPS increased during the supplementation period in both legs (rested: 9% ±1%; exercised: 17% ± 2%; P < 0.001) in LEU, but in the exercised leg only (7% ± 2%; P < 0.001) in CON"
  • Supplementing Breakfast with a Vitamin D and Leucine-Enriched Whey Protein Medical Nutrition Drink Enhances Postprandial Muscle Protein Synthesis and Muscle Mass in Healthy Older Men - J Nutr. 2017 Aug 23 - "Supplementing breakfast with a vitamin D and leucine-enriched whey protein medical nutrition drink stimulated postprandial muscle protein synthesis and increased muscle mass after 6 wk of intervention in healthy older adults and may therefore be a way to support muscle preservation in older people" - [Nutra USA]
  • International Society of Sports Nutrition Position Stand: protein and exercise - Journal of the International Society of Sports Nutrition, Jun 3, 2017 - "muscle protein synthesis (MPS) ... Acute protein doses should strive to contain 700–3000 mg of leucine and/or a higher relative leucine content, in addition to a balanced array of the essential amino acids (EAAs) ... Rapidly digested proteins that contain high proportions of essential amino acids (EAAs) and adequate leucine, are most effective in stimulating MPS" - [Nutra USA] -
  • Leucine Differentially Regulates Gene-Specific Translation in Mouse Skeletal Muscle - J Nutr. 2017 Jun 14 - "These results clarify the translation program acutely stimulated by leucine in mouse skeletal muscle and establish new methodologies for use in future studies of skeletal muscle disease or aging and further examination of downstream effects of leucine on gene expression" - See BulkSupplements Pure L-Leucine Powder (1 Kilogram).
  • L-leucine dietary supplementation modulates muscle protein degradation and increases pro-inflammatory cytokines in tumour-bearing rats - Cytokine. 2017 May 8;96:253-260 - "the leucine-supplemented tumour-bearing groups showed improvements in muscle mass and protein content, and in this specific situation, the leucine-rich diet led to an increase on the day in cytokine profile and proteasome subunits mainly on the 14th day, which subsequently had a modulating effect on tumour growth on the 21st day. These results indicate that the presence of leucine in the diet may modulate important aspects of the proteasomal pathway in cancer cachexia and may prevent muscle wasting due to the decrease in the cachexia index"
  • Leucine supplementation enhances integrative myofibrillar protein synthesis in free-living older men consuming lower- and higher-protein diets: a parallel-group crossover study - Am J Clin Nutr. 2016 Dec;104(6):1594-1606 - "We examined the impact of leucine co-ingestion with mixed macronutrient meals on integrated 3-d rates of myofibrillar protein synthesis (MyoPS) in free-living older men who consumed higher protein (HP) (1.2 g · kg-1 · d-1) or LP (0.8 g · kg-1 · d-1) in rested and resistance exercise (REX) conditions ... Leu co-ingestion with daily meals enhances integrated MyoPS in free-living older men in rested and REX conditions and is equally effective in older men who consume daily protein intakes greater than or equal to the RDA"
  • The impact of protein quality on the promotion of resistance exercise-induced changes in muscle mass - Nutr Metab (Lond). 2016 Sep 29;13:64 - "Protein ingestion and the resultant hyperaminoacidemia provides the building blocks (indispensable amino acids - IAA) for, and also triggers an increase in, muscle protein synthesis (MPS), suppression of muscle protein breakdown (MPB), and net positive protein balance (i.e., MPS > MPB). The key amino acid triggering the rise in MPS is leucine, which stimulates the mechanistic target of rapamycin complex-1, a key signalling protein, and triggers a rise in MPS. As such, ingested proteins with a high leucine content would be advantageous in triggering a rise in MPS. Thus, protein quality (reflected in IAA content and protein digestibility) has an impact on changes in MPS and could ultimately affect skeletal muscle mass. Protein quality has been measured by the protein digestibility-corrected amino acid score (PDCAAS); however, the digestible indispensable amino acid score (DIAAS) has been recommended as a better method for protein quality scoring. Under DIAAS there is the recognition that amino acids are individual nutrients and that protein quality is contingent on IAA content and ileal (as opposed to fecal) digestibility. Differences in protein quality may have important ramifications for exercise-induced changes in muscle mass gains made with resistance exercise as well as muscle remodelling" - [Nutra USA]
  • Activation of the AMPK/Sirt1 pathway by a leucine-metformin combination increases insulin sensitivity in skeletal muscle, and stimulates glucose and lipid metabolism and increases life span in Caenorhabditis elegans - Metabolism. 2016 Jul 9 - "We have previously shown leucine (Leu) to activate Sirt1 by lowering its KM for NAD+, thereby amplifying the effects of other sirtuin activators and improving insulin sensitivity. Metformin (Met) converges on this pathway both indirectly (via AMPK) and by direct activation of Sirt1 ... Leu and Met synergize to enable Sirt1 activation at low NAD+ concentrations (typical of energy replete states). Sirt1 and AMPK activations are required for Met-Leu's full action, which result in improvements in energy metabolism and insulin sensitivity" - See BulkSupplements Pure L-Leucine Powder (1 Kilogram) and metformin at The Antiaging Store.
  • Supplementation of Diabetic Rats with Leucine, Zinc, and Chromium: Effects on Function and Histological Structure of Testes - Int J Vitam Nutr Res. 2016 Jul 5:1-11 - "Administration of nutritional supplements to the diabetic rats improved testes morphology and reversed, although not completely, impairment of spermatogenesis. Treatment with nutritional supplements increased testicular length, height, width, and volume. All treatments increased the number of live sperm and the total number of epididymal sperm. Furthermore, nutritional supplements increased diameter of tubules, height of epithelium, and the number of cells in seminiferous tubules. These alleviating effects were more pronounced in animals treated with the leucine-zinc-chromium combination. The present results demonstrate beneficial effects of zinc, leucine, and chromium supplements to improve testes morphology and to restore spermatogenesis in type 2 diabetic rats"
  • 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 - J Am Coll Nutr. 2016 Jun 22:1-12 - "l-leucine increased skeletal muscle IGF-1 concentration in resistance-trained men"
  • The effects of phosphatidic acid supplementation on strength, body composition, muscular endurance, power, agility, and vertical jump in resistance trained men - J Int Soc Sports Nutr. 2016 Jun 2;13:24 - "Phosphatidic acid (PA) is a lipid messenger that has been shown to increase muscle protein synthesis via signaling stimulation of the mammalian target of rapamycin (mTOR). MaxxTOR® (MT) is a supplement that contains PA as the main active ingredient but also contains other synergistic mTOR signaling substances including L-Leucine, Beta-Hydroxy-Beta-Methylbutyrate (HMB), and Vitamin D3 ... participants were tested on one repetition maximum (1RM) leg press strength (LP), 1RM bench press strength (BP), push-ups to failure (PU), vertical jump (VJ), pro-agility shuttle time (AG), peak power output (P), lean body mass (LBM), fat mass (FM), and thigh muscle mass (TMM) ... There was a significant main effect (F(1,16) = 33.30, p < 0.001) for LBM where MT significantly increased LBM when compared to the PLA group (p < 0.001). Additionally, there was a significant main effect for LP (F(1,16) = 666.74, p < 0.001) and BP (F(1,16) = 126.36, p < 0.001) where both increased significantly more in MT than PLA group (p < 0.001). No significant differences between MT and PLA were noted for FM, TMM, VJ, AG, P, or PU" - [Nutra USA] - Note:  Seems like you might have gotten the same results with l-leucine (one of the ingredients in MaxxTOR®) alone.  See phosphatidic acid at Amazon.com, HMB at Amazon.com and leucine products at Amazon.com.
  • Enriching a protein drink with leucine augments muscle protein synthesis after resistance exercise in young and older men - Clin Nutr. 2016 Apr 30 - "Maximizing anabolic responses to feeding and exercise is crucial for muscle maintenance and adaptation to exercise training. We hypothesized that enriching a protein drink with leucine would improve anabolic responses to resistance exercise ... We conclude that addition of Leucine to a sub-maximal PRO bolus improves anabolic responses to RE in young and older men" - See See BulkSupplements Pure L-Leucine Powder (1 Kilogram).
  • Protein Intake and Muscle Health in Old Age: From Biological Plausibility to Clinical Evidence - Nutrients. 2016 May 14;8(5) - "Older persons, in particular, are at high risk of insufficient protein ingestion. Furthermore, the current recommended dietary allowance for protein (0.8 g/kg/day) might be inadequate for maintaining muscle health in older adults, probably as a consequence of "anabolic resistance" in aged muscle. Older individuals therefore need to ingest a greater quantity of protein to maintain muscle function. The quality of protein ingested is also essential to promoting muscle health. Given the role of leucine as the master dietary regulator of muscle protein turnover, the ingestion of protein sources enriched with this essential amino acid, or its metabolite β-hydroxy β-methylbutyrate, is thought to offer the greatest benefit in terms of preservation of muscle mass and function in old age"
  • Medium-Chain Triglycerides in Combination with Leucine and Vitamin D Increase Muscle Strength and Function in Frail Elderly Adults in a Randomized Controlled Trial - J Nutr. 2016 Apr 13 - "Sarcopenia, the loss of skeletal muscle mass, strength, and function, is common in elderly individuals but difficult to treat  ... The first group received a daily L-leucine (1.2 g) and cholecalciferol (20 μg)-enriched supplement with 6 g medium-chain triglycerides (TGs) (MCTs) (LD + MCT); the second group received the same leucine and cholecalciferol-enriched supplement with 6 g long-chain TGs (LD + LCT); and the third group did not receive any supplements (control). The supplement and oils were taken at dinner, and changes in muscle mass, strength, and function were monitored ... After 3 mo, participants in the LD + MCT group had a 13.1% increase in right-hand grip strength (1.2 ± 1.0 kg,P< 0.01), a 12.5% increase in walking speed (0.078 ± 0.080 m/s,P< 0.05), a 68.2% increase in a 10-s leg open-and-close test performance (2.31 ± 1.68n/10 s,P< 0.001), and a 28.2% increase in peak expiratory flow (53 ± 59 L/min,P< 0.01). No significant improvements in muscle mass, strength, or function were observed in the LD + LCT or control groups" - See BulkSupplements Pure L-Leucine Powder (1 Kilogram).
  • Lean body mass change over 6 years is associated with dietary leucine intake in an older Danish population - Br J Nutr. 2016 Mar 16:1-7 - "Higher protein intake, and particularly higher leucine intake, is associated with attenuated loss of lean body mass (LBM) over time in older individuals. Dietary leucine is thought to be a key mediator of anabolism ... Dietary leucine intake was assessed at baseline and after 6 years in men and women, aged 35-65 years, participating in the Danish cohort of the WHO-MONICA (Multinational MONItoring of trends and determinants in CArdiovascular disease) study (n 368) ... Older participants in the highest quartile of leucine intake (7·1 g/d) experienced LBM maintenance, whereas lower intakes were associated with LBM loss over 6 years ... This study corroborates findings from laboratory investigations in relation to protein and leucine intakes and LBM change"
  • Leucine partially protects muscle mass and function during bed rest in middle-aged adults - Am J Clin Nutr. 2015 Dec 30 - "muscle protein synthesis (MPS) ... leucine supplementation (LEU group: 0.06 g ∙ kg-1 ∙ meal-1) or an alanine control (CON group) during 14 d of bed rest ... Leucine protected knee extensor peak torque (CON compared with LEU group: -15% ± 2% and -7% ± 3%; group × time interaction, P < 0.05) and endurance (CON compared with LEU: -14% ± 3% and -2% ± 4%; group × time interaction, P < 0.05), prevented an increase in body fat percentage (group × time interaction, P < 0.05), and reduced whole-body lean mass loss after 7 d (CON compared with LEU: -1.5 ± 0.3 and -0.8 ± 0.3 kg; group × time interaction, P < 0.05) but not 14 d (CON compared with LEU: -1.5 ± 0.3 and -1.0 ± 0.3 kg) of bed rest. Leucine also maintained muscle quality (peak torque/kg leg lean mass) after 14 d of bed-rest inactivity (CON compared with LEU: -9% ± 2% and +1% ± 3%; group × time interaction, P < 0.05)"
  • Impact of Leucine Supplementation on Exercise Training Induced Anti-Cardiac Remodeling Effect in Heart Failure Mice - Nutrients. 2015 May 15 - "Leucine supplementation potentiates the effects of aerobic exercise training (AET) on skeletal muscle ... Leucine supplementation potentiated AET effects on exercise tolerance, which might be related to its recognized impact on skeletal muscle"
  • Protein and healthy aging - Am J Clin Nutr. 2015 Apr 29 - "The potential benefits of young and middle-aged adults adopting a diet pattern whereby adequate protein is consumed at each meal as a countermeasure to sarcopenia are presented and discussed. For example, meeting a protein threshold (~25-30 g/meal) represents a promising, yet still largely unexplored dietary strategy to help maintain muscle mass and function. For many older adults, breakfast is a carbohydrate-dominated lower-protein meal and represents an opportunity to improve and more evenly distribute daily protein intake. Although both animal and plant-based proteins can provide the required essential amino acids for health, animal proteins generally have a higher proportion of the amino acid leucine. Leucine plays a key role in stimulating translation initiation and muscle protein anabolism and is the focus of ongoing research. Protein requirements should be assessed in the light of habitual physical activity. An evenly distributed protein diet provides a framework that allows older adults to benefit from the synergistic anabolic effect of protein and physical activity" - Note:  I put a scoop of leucine into an empty jelly jar with about a third cup of water and shake it then swill it every morning just before breakfast.  It's probably the worst thing you'll ever taste but I'm convinced it works for preserving muscles.
  • Leucine amplifies the effects of metformin on insulin sensitivity and glycemic control in diet-induced obese mice - Metabolism. 2015 Mar 19 - "These data demonstrate that adding Leu to Met enables a dose reduction of 66% with improved efficacy and of 83% with comparable efficacy to standard metformin in diet-induced obese mice"
  • Effects of leucine-rich protein supplements on anthropometric parameter and muscle strength in the elderly: a systematic review and meta-analysis - J Nutr Health Aging. 2015;19(4):437-46 - "It is concluded that leucine supplementation was found to exert beneficial effects on body weight, body mass index, and lean body mass in older persons in those subjects already prone to sarcopenia, but not muscle strength" - Note:  Here's what I take. I put a scoop and a half of leucine in about a half cup of water in a small jelly jar and shake it and swill it. It's probably the worst think you could taste: Serious Nutrition Solutions Leucine - 500 Grams at Amazon.com.
  • 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 - Br J Nutr. 2014 Sep 19:1-10 - "These findings suggest that leucine supplementation is useful to address the age-related decline in muscle mass in elderly individuals, as it increases the muscle protein fractional synthetic rate"
  • Leucine supplementation of a low-protein mixed macronutrient beverage enhances myofibrillar protein synthesis in young men: a double-blind, randomized trial - Am J Clin Nutr. 2013 Nov 27 "40 men (21 ± 1 y) completed unilateral knee-extensor resistance exercise before the ingestion of 25 g whey protein (W25) (3.0 g leucine), 6.25 g whey protein (W6) (0.75g leucine), 6.25 g whey protein supplemented with leucine to 3.0 g total leucine (W6+Low-Leu), 6.25 g whey protein supplemented with leucine to 5.0 g total leucine (W6+High-Leu), or 6.25 g whey protein supplemented with leucine, isoleucine, and valine to 5.0 g total leucine ... A low-protein (6.25 g) mixed macronutrient beverage can be as effective as a high-protein dose (25 g) at stimulating increased MPS rates when supplemented with a high (5.0 g total leucine) amount of leucine. These results have important implications for formulations of protein beverages designed to enhance muscle anabolism"
  • Leucine supplementation of a low-protein mixed macronutrient beverage enhances myofibrillar protein synthesis in young men: a double-blind, randomized trial - Am J Clin Nutr. 2013 Nov 27 - "myofibrillar protein synthesis (MPS) ... A low-protein (6.25 g) mixed macronutrient beverage can be as effective as a high-protein dose (25 g) at stimulating increased MPS rates when supplemented with a high (5.0 g total leucine) amount of leucine. These results have important implications for formulations of protein beverages designed to enhance muscle anabolism" - [Nutra USA] - Note:  That's about what I take per day in the one heaping scoop.  It's got to be the worst tasting substance in the world.  I put the scoop in a small jar with about a third cup of water, shake it and swill in then rinse the jar a couple more times to get it all.
  • Whey protein supplementation during resistance training augments lean body mass - J Am Coll Nutr. 2013 Apr;32(2):122-35 - "Compared to soy, whey protein is higher in leucine, absorbed quicker and results in a more pronounced increase in muscle protein synthesis ... randomized non-resistance-trained men and women into groups who consumed daily isocaloric supplements containing carbohydrate (carb; n = 22), whey protein (whey; n = 19), or soy protein (soy; n = 22) ... Lean body mass gains were significantly (p < 0.05) greater in whey (3.3 +/- 1.5 kg) than carb (2.3 +/- 1.7 kg) and soy (1.8 +/- 1.6 kg). Fat mass decreased slightly but there were no differences between groups. Fasting concentrations of leucine were significantly elevated (20%) and postexercise plasma leucine increased more than 2-fold in whey. Fasting leucine concentrations were positively correlated with lean body mass responses"
  • Similar effects of leucine rich and regular dairy products on muscle mass and functions of older polymyalgia rheumatica patients: a randomized crossover trial - J Nutr Health Aging. 2011;15(6):462-7 - "Patients performed as many stand ups as possible twice a day after which they ingested a regular (Control) or a whey protein enriched dairy product with high leucine content (Test). The 8-week intervention periods were separated by a 4-week wash-out ... The 16-week home-based post-exercise supplementation resulted in a 1.8% increase (p = 0.052) in lower limb muscle mass. Walking speed (+5.3%, p = 0.007) and chair stand test performance (-12.2 %, p < 0.001) were also improved. Furthermore, a tendency for increased jump power (+3.0%, p = 0.084) was observed. However, significant and consistent differences were not found in the changes of muscle mass indices or muscle functions between supplements, but the test supplement tended to prevent accumulation of body fat. Conclusion: A low intensity home based exercise program combined with post-exercise milk protein supplementation is feasible despite some gastrointestinal complaints and seems effective in improving the muscle mass and functions of older persons with a inflammatory disease. Further studies are needed to establish, whether and to what extent the use of leucine-enriched whey products prevent or treat age-associated sarcopenia and whether they are superior to the present commercial milk products"
  • Leucine and {alpha}-Ketoisocaproic Acid, but Not Norleucine, Stimulate Skeletal Muscle Protein Synthesis in Neonatal Pigs - J Nutr. 2010 Jun 9
  • Long-term leucine supplementation does not increase muscle mass or strength in healthy elderly men - Am J Clin Nutr. 2009 Mar 25
  • A high proportion of leucine is required for optimal stimulation of the rate of muscle protein synthesis by essential amino acids in the elderly - Am J Physiol Endocrinol Metab. 2006 Feb 28
  • Amino acids and muscle loss with aging - J Nutr. 2006 Jan;136(1):277S-80S - "Recent data suggest that excess leucine may be able to overcome this age-related resistance of muscle proteins to leucine. For this reason, long-term essential amino acid supplementation may be a useful tool for the prevention and treatment of sarcopenia, particularly if excess leucine is provided in the supplement"