Leucine Is A Critical Factor Determining Protein Quantity And Quality Of A Complete Meal To Initiate Muscle Protein Synthesis

Emerging research suggests that high protein diets may have a role in preventing obesity, sarcopenia, diabetes, and optimizing muscle mass and bone health. Evidence is mounting that these benefits may be in part due to the amino acid leucine (leu) and its unique ability to stimulate muscle protein synthesis (MPS). Current dietary protein recommendations for protein quantity and quality are defined as the minimum daily amount to prevent deficiencies of limiting amino acids and increases in plasma amino acids are regarded as 0́8excess0́9 or inefficient use of amino acids due to increased amino acid oxidation. This view does not account for the meal responses of MPS associated with intracellular signaling in response to increasing plasma leu. The goal of this research was to elucidate the physiological role that leu plays in complete meals and to determine if the meal distribution of protein or leu is important for optimization of muscle mass. My hypothesis was that optimum MPS would equate to maximum signaling response of the kinase known as mammalian target of rapamycin (mTOR) and directly related to post-prandial plasma leu concentration. Ultimately, the leu content of individual meals and the number of meal per day with sufficient leu to increase MPS will influence muscle mass, lean body mass and long term body composition In vivo work with purified solutions established that leu has a regulatory role for initiating MPS by activating mTOR and there is a clear threshold of leu required to increase plasma leu and stimulate MPS. In order to test the role of leu in complete meals we examined the duration and peak activation of MPS and mTOR signaling in response to complete test meals containing 10, 20, and 30% of total energy from wheat and whey protein (6.8 and 10.9% leu) respectively. We determined that whey increased plasma leu, mTOR signaling, and MPS more than wheat at all protein intakes. Stimulation of MPS after meals last for 3 hours with a peak at 90 minutes, however plasma leu and mTOR signaling remained at a plateau for 3 hours before decreasing. Meal leu content and the increases in postprandial plasma leu were closely associated with peak activation of mTOR signaling and MPS but did not determine the duration of protein synthesis which demonstrated a refractory response to the constant elevations in plasma leu. Experiment 2 examined the potential to use leu to predict the quality of individual proteins to stimulate mTOR signaling and MPS. Adult rats were adapted for 2 weeks to a meal-feeding protocol with complete diets containing 16% protein but with different leu contents using wheat, soy, egg, or whey proteins (6.8, 8.0, 8.8, and 10.9% leu). Animals fed egg and whey significantly increased plasma leu and MPS whereas animals fed wheat and soy did not. The leu content of the meals predicted mTOR signaling and peak MPS responses and were closely related to changes in plasma leu. These findings support the hypothesis that there is a meal leu threshold for increasing plasma leu. While experiment 2 provided proof of concept that there is a meal threshold for leu stimulation of MPS, the critical outcomes are changes in muscle mass or body composition. This study tested the hypothesis that long-term meal-feeding of isonitrogenous/isocaloric diets with 16/54/30% of energy from protein/carbohydrates/lipids, respectively, using protein sources (wheat, soy, egg, whey) with different leu contents could produce body composition and muscle weight outcomes in relation to the changes in postprandial MPS and plasma leu observed in the previous experiments. Based on the leu threshold observed in the previous experiment, the diets were designed such that animals fed egg and whey proteins would receive sufficient leu during each of the three meals to achieve three stimulations of MPS per day as opposed to animals fed wheat and soy proteins with lower leu contents that would achieve the leu threshold only at the larger dinner meal. After 11 weeks of meal-feeding, body composition, lean body mass, and gastrocnemius muscle weights were positively related to the leu content of the diet and reflected the ability of the respective diets to increase postprandial plasma leu and MPS. Finally, we tested the hypothesis that long-term distribution of protein/leu could make a difference in body composition by feeding isocaloric/isonitrogenous meals containing whey protein evenly distributed to achieve the leu thresholds at each of 3 meals (ED-Whey) daily or unevenly distributed over 3 meals (UD-Whey) with only the dinner meal exceeding the leu threshold. The ED-Whey treatment with evenly distributed leu produced multiple stimulations of MPS throughout the day and larger gastrocnemius muscle weights compared to the UD-whey that only achieved stimulation of MPS at a single meal. While muscle mass was larger in the ED-Whey treatment, total lean body mass was not different between groups. This may have been due to the large protein (i.e. nitrogen) content of the dinner meal in the UD-Whey group producing a shift in lean body mass deposition to the liver and visceral tissues, which were larger in the UD-Whey group. In summary, the leu content of complete meals is an important regulator of MPS and produces different body composition outcomes with long term feeding of diets differing in leu contents and leu/protein distribution. These results cannot be explained by limiting amino acids and are not accounted for by current protein quantity and quality recommendations.

This title includes a number of Open Access chapters. Sarcopenia—the loss of muscle mass and strength that occurs with advancing age—is a major health challenge, particularly in North America, Europe, and Japan, which have large aging populations. This compendium volume is a valuable addition to the existing literature, providing state-of-the-art information on the most effective prevention and treatment options. Included are research articles on nutrition management and the prevention of sarcopenia; protein therapy for sarcopenia; effect of exercise on sarcopenia; and other therapeutic strategies, including antioxidants and steroids.

THE ULTIMATE GUIDE TO THE POWERFUL AMINO ACID THAT SUPERCHARGES YOUR METABOLISM If your goal is to improve strength and vitality, sugar is the kryptonite that will hold you back. Fortunately, nature has provided the ultimate anti-sugar: leucine. This book reveals the amazing ability of leucine to combat the harmful effects of sugar, burn deep levels of fat and rapidly build muscle. With advice on getting started, building a personalized plan and successfully reaching your goals, The Leucine Factor Diet offers you a path for becoming healthy, strong and lean. Author Dr. Victor Prisk, an orthopedic surgeon, champion gymnast and bodybuilder, teaches how to optimize the leucine content of your food while creating nutritious and delicious meals. With detailed information on dietary supplements, resistance exercise and medical awareness, The Leucine Factor Diet brings together all the key elements to successful muscle building. Whether you are a competitive athlete or weekend warrior, this book has everything you need to take your fitness to the next level.

It is a commonly held belief that athletes, particularly body builders, have greater requirements for dietary protein than sedentary individuals. However, the evidence in support of this contention is controversial. This book is the latest in a series of publications designed to inform both civilian and military scientists and personnel about issues related to nutrition and military service. Among the many other stressors they experience, soldiers face unique nutritional demands during combat. Of particular concern is the role that dietary protein might play in controlling muscle mass and strength, response to injury and infection, and cognitive performance. The first part of the book contains the committee's summary of the workshop, responses to the Army's questions, conclusions, and recommendations. The remainder of the book contains papers contributed by speakers at the workshop on such topics as, the effects of aging and hormones on regulation of muscle mass and function, alterations in protein metabolism due to the stress of injury or infection, the role of individual amino acids, the components of proteins, as neurotransmitters, hormones, and modulators of various physiological processes, and the efficacy and safety considerations associated with dietary supplements aimed at enhancing performance.

With the constant flow of information related to sports nutrition coming from scholarly journals, it is difficult to sift through it all and determine what is relevant. Sports Nutrition: Enhancing Athletic Performance helps in this endeavor, with more than 1,000 references from top academic journals, offering critical knowledge concerning nutrient ingestion for enhancing exercise and sports performance. This book offers a clear focus on scientifically based sports nutrition advice to maximize performance. It also addresses exercise metabolism, which governs how nutrients exert physiologic effects that lead to increased athletic potential. The book examines the three key macronutrients: fat, carbohydrate, and protein. It discusses various aspects of macronutrient metabolism, including differences between a body at rest and during high-intensity exercise. Topics covered in the text include the following: Nutrient timing Leucine threshold to optimize muscle protein synthesis Carbohydrate manipulations for better endurance- and resistance-exercise performance Dietary fat intake recommendations for improving performance Carbohydrate loading strategies Optimal amounts of protein to ingest on a meal-by-meal basis Pre-exercise dietary fat intake strategies Comparison of high-quality proteins In addition to enhancing performance, the book describes how to improve body composition, presenting a scientifically based strategy for losing body fat while maintaining precious lean muscle mass. Four principles of fat loss are set forth that are integral for success in optimizing body composition. This book presents both performance nutrition principles and exercise biochemistry, addressing the key questions of what, when, and how much to ingest for improved performance and training recovery.

"Which of the following will yield the fastest measurable change in performance and/or body composition? (A) changes in training. (B) changes in diet. (C) use of sports supplements. (D) they all work equally well. If you answered 'C,' go to the head of the class. That's right; the proper use of sports supplements can produce changes in minutes (e.g. caffeine), days (e.g. creatine) and weeks (e.g. beta-alanine). Yet we are bombarded by muddled thinking from the mainstream media telling us that 'creatine causes cramps,' 'high protein diets are bad for your kidneys,' 'supplements aren't needed as long as you eat a balanced diet' and other ideas that are void of data. Sports Nutrition & Performance Enhancing Supplements (eds. Abbie Smith-Ryan PhD CSCS*D CISSN and Jose Antonio PhD FNSCA FISSN. Linus Publications) is a focused resource that will give you the latest sports nutrition science, and eradicate the intellectually lazy positions held so dearly by the anti-supplement crowd."--Amazon.

"Background: Frailty is a clinical condition associated with loss of muscle mass and strength, whose loss is termed sarcopenia, of which age-related resistance to anabolic stimuli is considered a key factor. Age-related anabolic resistance can be mitigated by a higher protein intake than presently recommended for the general population and has lower insulin sensitivity (IS) as a contributing factor, while mitochondria are centrally implicated in frailty and sarcopenia. Resistance training (RT) is the strongest stimuli to counteract sarcopenia via increasing muscle protein synthesis in the presence of sufficient amino acids, and may also stimulate mitochondrial biogenesis, as well as improve IS in frail older women. Leucine is a unique amino acid that acutely increases muscle protein synthesis independent of insulin. Leucine has paradoxically been shown to have both potential therapeutic value while also being implicated in the pathological development of insulin resistance. Furthermore, leucine has recently been shown to increase mitochondrial biogenesis in myocytes. The effects of chronic leucine supplementation in conjunction with RT on these factors within the context of frailty are currently unknown. Objective: The purpose of this double-blinded placebo-controlled study is to determine the effects of leucine supplementation and RT on indices of anabolism, insulin sensitivity, and mitochondria function in pre-frail and frail older women consuming optimal protein intake. Methodology: Nineteen pre-frail and frail elderly women (77.5 ± 1.3 y), based on the Frailty Phenotype, underwent 3-months of RT 3x/week with protein-optimized diet (~1.2 g·kg BW−1d·−1) and were randomized to 7.5 g/d of leucine supplementation or an isonitrogenous quantity of placebo (alanine). Indices of 1) insulin sensitivity during a metabolic test meal; 2) mitochondrial content (VDAC protein), function (respiration and reactive oxygen species production), and sensitivity to apoptosis (calcium retention capacity and time to mitochondria permeability transition pore opening) in permeabilized muscle fibers; and 3) muscle protein synthesis determined using L-[ring-2H5]phenylalanine infusion in the postabsorptive and postprandial states, muscle fiber profile by immunohistochemistry, body composition by Dual X-ray Absorptiometry, physical function tests and maximal isometric strength were measured pre- and post-intervention. Results: Our main findings were that compared to 12 weeks of RT in pre-frail and frail older women consuming an optimal protein intake, additional leucine supplementation had: 1) no detrimental nor beneficial effect on insulin sensitivity; 2) increased mitochondrial content without affecting mitochondria function, capacity, or sensitivity to apoptosis; and 3) no added benefit on improvements in muscle protein synthesis, muscle function, and Frailty Phenotype. Conclusion: Leucine supplementation does not appear to influence insulin sensitivity, and although leucine increased mitochondrial content, this occurred without associated improvements in mitochondria function in older women consuming an optimal protein intake and undertaking RT in the context of frailty. The RT and dietary protein intake as described in this study appear to effectively and meaningfully stimulate basal (postabsorptive) muscle protein synthesis translating into measurable gains in muscle protein accretion, strength, and function resulting in marked improvements in the Frailty Phenotype." --

Since its introduction in 1943 Recommended Dietary Allowances has become the accepted source of nutrient allowances for healthy people. These Recommended Dietary Allowances (RDAs) are used throughout the food and health fields. Additionally, RDAs serve as the basis for the U.S. Recommended Daily Allowances, the Food and Drug Administration's standards for nutrition labeling of foods. The 10th Edition includes research results and expert interpretations from years of progress in nutrition research since the previous edition and provides not only RDAs but also "Estimated Safe and Adequate Daily Dietary Intakes"â€"provisional values for nutrients where data were insufficient to set an RDA. Organized by nutrient for ready reference, the volume reviews the function of each nutrient in the human body, sources of supply, effects of deficiencies and excessive intakes, relevant study results, and more. The volume concludes with the invaluable "Summary Table of Recommended Dietary Allowances," a convenient and practical summary of the recommendations.

Nutrition and Enhanced Sports Performance: Muscle Building, Endurance and Strength, Second Edition, includes comprehensive sections on the role of nutrition in human health, various types of physical exercises, including cardiovascular training, resistance training, aerobic and anaerobic exercises, bioenergetics and energy balance, and the nutritional requirements associated with each. Other sections cover sports and nutritional requirements, the molecular mechanisms involved in muscle building, an exhaustive review of various foods, minerals, supplements, phytochemicals, amino acids, transition metals, competition training, healthy cooking, physical training, and lifestyle and dietary recommendations for sports performance. This updated edition includes new chapters on mood, alertness, calmness and psychomotor performance in sports, extreme sports, natural myostatin inhibitor and lean body mass, the benefits of caffeine in sport nutrition formulations, the role of vitamin D in athletic performance, probiotics and muscle mass. Provides a comprehensive appraisal of the nutritional benefits of exercise in human health Compiles chapters reviewing the nutritional prophylaxis in human health Addresses performance enhancement drugs and sports supplements Presents various types of physical exercises and addresses exercise and nutritional requirements in special populations Discusses sports nutrition and the molecular mechanisms involved in muscle building Contains an exhaustive review of various food, minerals, supplements, phytochemicals, amino acids, transition metals, small molecules and other ergogenic agents Highlights the aspects of healthy cooking, physical training, lifestyle and dietary recommendations for sports performance