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Home > Anti-aging Research > L-Leucine


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  • 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" - See BulkSupplements Pure L-Leucine Powder (1 Kilogram).
  • 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"


  • 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] - See BulkSupplements Pure L-Leucine Powder (1 Kilogram).
  • 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 IAS.
  • 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"
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