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Journal of the International Society of... 2018Controversy exists about the maximum amount of protein that can be utilized for lean tissue-building purposes in a single meal for those involved in regimented... (Review)
Review
Controversy exists about the maximum amount of protein that can be utilized for lean tissue-building purposes in a single meal for those involved in regimented resistance training. It has been proposed that muscle protein synthesis is maximized in young adults with an intake of ~ 20-25 g of a high-quality protein; anything above this amount is believed to be oxidized for energy or transaminated to form urea and other organic acids. However, these findings are specific to the provision of fast-digesting proteins without the addition of other macronutrients. Consumption of slower-acting protein sources, particularly when consumed in combination with other macronutrients, would delay absorption and thus conceivably enhance the utilization of the constituent amino acids. The purpose of this paper was twofold: 1) to objectively review the literature in an effort to determine an upper anabolic threshold for per-meal protein intake; 2) draw relevant conclusions based on the current data so as to elucidate guidelines for per-meal daily protein distribution to optimize lean tissue accretion. Both acute and long-term studies on the topic were evaluated and their findings placed into context with respect to per-meal utilization of protein and the associated implications to distribution of protein feedings across the course of a day. The preponderance of data indicate that while consumption of higher protein doses (> 20 g) results in greater AA oxidation, this is not the fate for all the additional ingested AAs as some are utilized for tissue-building purposes. Based on the current evidence, we conclude that to maximize anabolism one should consume protein at a target intake of 0.4 g/kg/meal across a minimum of four meals in order to reach a of 1.6 g/kg/day. Using the upper daily intake of 2.2 g/kg/day reported in the literature spread out over the same four meals would necessitate a maximum of 0.55 g/kg/meal.
Topics: Dietary Proteins; Humans; Meals; Muscle Proteins; Resistance Training; Sports Nutritional Physiological Phenomena
PubMed: 29497353
DOI: 10.1186/s12970-018-0215-1 -
International Journal of Sport... May 2021Branched-chain amino acids (BCAA) are one of the most popular sports supplements, marketed under the premise that they enhance muscular adaptations. Despite their... (Review)
Review
Branched-chain amino acids (BCAA) are one of the most popular sports supplements, marketed under the premise that they enhance muscular adaptations. Despite their prevalent consumption among athletes and the general public, the efficacy of BCAA has been an ongoing source of controversy in the sports nutrition field. Early support for BCAA supplementation was derived from extrapolation of mechanistic data on their role in muscle protein metabolism. Of the three BCAA, leucine has received the most attention because of its ability to stimulate the initial acute anabolic response. However, a substantial body of both acute and longitudinal research has now accumulated on the topic, affording the ability to scrutinize the effects of BCAA and leucine from a practical standpoint. This article aims to critically review the current literature and draw evidence-based conclusions about the putative benefits of BCAA or leucine supplementation on muscle strength and hypertrophy as well as illuminate gaps in the literature that warrant future study.
Topics: Age Factors; Amino Acids, Branched-Chain; Dietary Proteins; Dietary Supplements; Humans; Leucine; Muscle Proteins; Muscle Strength; Muscle, Skeletal; Resistance Training
PubMed: 33741748
DOI: 10.1123/ijsnem.2020-0356 -
American Journal of Physiology. Cell... Jun 2022Decreased skeletal muscle contractile activity (disuse) or unloading leads to muscle mass loss, also known as muscle atrophy. The balance between muscle protein... (Review)
Review
Decreased skeletal muscle contractile activity (disuse) or unloading leads to muscle mass loss, also known as muscle atrophy. The balance between muscle protein synthesis (MPS) and muscle protein breakdown (MPB) is the primary determinant of skeletal muscle mass. A reduced mechanical load on skeletal muscle is one of the main external factors leading to muscle atrophy. However, endocrine and inflammatory factors can act synergistically in catabolic states, amplifying the atrophy process and accelerating its progression. In addition, older individuals display aging-induced anabolic resistance, which can predispose this population to more pronounced effects when exposed to periods of reduced physical activity or mechanical unloading. Different cellular mechanisms contribute to the regulation of muscle protein balance during skeletal muscle atrophy. This review summarizes the effects of muscle disuse on muscle protein balance and the molecular mechanisms involved in muscle atrophy in the absence or presence of disease. Finally, a discussion of the current literature describing efficient strategies to prevent or improve the recovery from muscle atrophy is also presented.
Topics: Aging; Humans; Muscle Proteins; Muscle, Skeletal; Muscular Atrophy; Muscular Disorders, Atrophic
PubMed: 35476500
DOI: 10.1152/ajpcell.00425.2021 -
Amino Acids Dec 2018The postprandial rise in essential amino acid (EAA) concentrations modulates the increase in muscle protein synthesis rates after protein ingestion. The EAA content and...
The postprandial rise in essential amino acid (EAA) concentrations modulates the increase in muscle protein synthesis rates after protein ingestion. The EAA content and AA composition of the dietary protein source contribute to the differential muscle protein synthetic response to the ingestion of different proteins. Lower EAA contents and specific lack of sufficient leucine, lysine, and/or methionine may be responsible for the lower anabolic capacity of plant-based compared with animal-based proteins. We compared EAA contents and AA composition of a large selection of plant-based protein sources with animal-based proteins and human skeletal muscle protein. AA composition of oat, lupin, wheat, hemp, microalgae, soy, brown rice, pea, corn, potato, milk, whey, caseinate, casein, egg, and human skeletal muscle protein were assessed using UPLC-MS/MS. EAA contents of plant-based protein isolates such as oat (21%), lupin (21%), and wheat (22%) were lower than animal-based proteins (whey 43%, milk 39%, casein 34%, and egg 32%) and muscle protein (38%). AA profiles largely differed among plant-based proteins with leucine contents ranging from 5.1% for hemp to 13.5% for corn protein, compared to 9.0% for milk, 7.0% for egg, and 7.6% for muscle protein. Methionine and lysine were typically lower in plant-based proteins (1.0 ± 0.3 and 3.6 ± 0.6%) compared with animal-based proteins (2.5 ± 0.1 and 7.0 ± 0.6%) and muscle protein (2.0 and 7.8%, respectively). In conclusion, there are large differences in EAA contents and AA composition between various plant-based protein isolates. Combinations of various plant-based protein isolates or blends of animal and plant-based proteins can provide protein characteristics that closely reflect the typical characteristics of animal-based proteins.
Topics: Amino Acids; Amino Acids, Essential; Chromatography, Liquid; Functional Food; Humans; Muscle Proteins; Muscle, Skeletal; Plant Proteins, Dietary; Protein Biosynthesis; Tandem Mass Spectrometry
PubMed: 30167963
DOI: 10.1007/s00726-018-2640-5 -
Journal of the International Society of... 2017The branched chain amino acids (BCAAs) are leucine, valine and isoleucine. A multi-million dollar industry of nutritional supplements has grown around the concept that... (Review)
Review
The branched chain amino acids (BCAAs) are leucine, valine and isoleucine. A multi-million dollar industry of nutritional supplements has grown around the concept that dietary supplements of BCAAs alone produce an anabolic response in humans driven by a stimulation of muscle protein synthesis. In this brief review the theoretical and empirical bases for that claim are discussed. Theoretically, the maximal stimulation of muscle protein synthesis in the post-absorptive state in response to BCAAs alone is the difference between muscle protein breakdown and muscle protein synthesis (about 30% greater than synthesis), because the other EAAs required for synthesis of new protein can only be derived from muscle protein breakdown. Realistically, a maximal increase in muscle protein synthesis of 30% is an over-estimate because the obligatory oxidation of EAAs can never be completely suppressed. An extensive search of the literature has revealed no studies in human subjects in which the response of muscle protein synthesis to orally-ingested BCAAs alone was quantified, and only two studies in which the effect of intravenously infused BCAAs alone was assessed. Both of these intravenous infusion studies found that BCAAs decreased muscle protein synthesis as well as protein breakdown, meaning a decrease in muscle protein turnover. The catabolic state in which the rate of muscle protein breakdown exceeded the rate of muscle protein synthesis persisted during BCAA infusion. We conclude that the claim that consumption of dietary BCAAs stimulates muscle protein synthesis or produces an anabolic response in human subjects is unwarranted.
Topics: Amino Acids, Branched-Chain; Anabolic Agents; Diet; Dietary Supplements; Humans; Muscle Proteins; Protein Biosynthesis
PubMed: 28852372
DOI: 10.1186/s12970-017-0184-9 -
Nutrients Dec 2020Ingesting protein-containing supplements and foods provides essential amino acids (EAA) necessary to increase muscle and whole-body protein synthesis (WBPS). Large...
Ingesting protein-containing supplements and foods provides essential amino acids (EAA) necessary to increase muscle and whole-body protein synthesis (WBPS). Large variations exist in the EAA composition of supplements and foods, ranging from free-form amino acids to whole protein foods. We sought to investigate how changes in peripheral EAA after ingesting various protein and free amino acid formats altered muscle and whole-body protein synthesis. Data were compiled from four previous studies that used primed, constant infusions of L-(ring-H)-phenylalanine and L-(3,3-H)-tyrosine to determine fractional synthetic rate of muscle protein (FSR), WBPS, and circulating EAA concentrations. Stepwise regression indicated that max EAA concentration (EAAC; R = 0.524, < 0.001), EAAC (R = 0.341, < 0.001), and change in EAA concentration (ΔEAA; R = 0.345, < 0.001) were the strongest predictors for postprandial FSR, Δ (change from post absorptive to postprandial) FSR, and ΔWBPS, respectively. Within our dataset, the stepwise regression equation indicated that a 100% increase in peripheral EAA concentrations increases FSR by ~34%. Further, we observed significant ( < 0.05) positive (R = 0.420-0.724) correlations between the plasma EAA area under the curve above baseline, EAAC, ΔEAA, and rate to EAAC to postprandial FSR, ΔFSR, and ΔWBPS. Taken together our results indicate that across a large variety of EAA/protein-containing formats and food, large increases in peripheral EAA concentrations are required to drive a robust increase in muscle and whole-body protein synthesis.
Topics: Aging; Amino Acids; Amino Acids, Essential; Dietary Supplements; Eating; Food; Humans; Kinetics; Male; Metabolism; Muscle Proteins; Muscle, Skeletal; Phenylalanine; Postprandial Period; Protein Biosynthesis; Whey Proteins
PubMed: 33276485
DOI: 10.3390/nu12123717 -
Journal of Applied Physiology... Mar 2017Exercise results in the rapid remodeling of skeletal muscle. This process is underpinned by acute and chronic changes in both gene and protein synthesis. In this short... (Review)
Review
Exercise results in the rapid remodeling of skeletal muscle. This process is underpinned by acute and chronic changes in both gene and protein synthesis. In this short review we provide a brief summary of our current understanding regarding how exercise influences these processes as well as the subsequent impact on muscle protein turnover and resultant shift in muscle phenotype. We explore concepts of ribosomal biogenesis and the potential role of increased translational capacity vs. translational efficiency in contributing to muscular hypertrophy. We also examine whether high-intensity sprinting-type exercise promotes changes in protein turnover that lead to hypertrophy or merely a change in mitochondrial content. Finally, we propose novel areas for future study that will fill existing knowledge gaps in the fields of translational research and exercise science.
Topics: Adaptation, Physiological; Animals; Gene Expression Regulation; Humans; Muscle Contraction; Muscle Proteins; Muscle, Skeletal; Protein Biosynthesis; Recovery of Function; Resistance Training
PubMed: 27742803
DOI: 10.1152/japplphysiol.00613.2016 -
Sports Medicine (Auckland, N.Z.) Sep 2021There is a global trend of an increased interest in plant-based diets. This includes an increase in the consumption of plant-based proteins at the expense of... (Review)
Review
There is a global trend of an increased interest in plant-based diets. This includes an increase in the consumption of plant-based proteins at the expense of animal-based proteins. Plant-derived proteins are now also frequently applied in sports nutrition. So far, we have learned that the ingestion of plant-derived proteins, such as soy and wheat protein, result in lower post-prandial muscle protein synthesis responses when compared with the ingestion of an equivalent amount of animal-based protein. The lesser anabolic properties of plant-based versus animal-derived proteins may be attributed to differences in their protein digestion and amino acid absorption kinetics, as well as to differences in amino acid composition between these protein sources. Most plant-based proteins have a low essential amino acid content and are often deficient in one or more specific amino acids, such as lysine and methionine. However, there are large differences in amino acid composition between various plant-derived proteins or plant-based protein sources. So far, only a few studies have directly compared the muscle protein synthetic response following the ingestion of a plant-derived protein versus a high(er) quality animal-derived protein. The proposed lower anabolic properties of plant- versus animal-derived proteins may be compensated for by (i) consuming a greater amount of the plant-derived protein or plant-based protein source to compensate for the lesser quality; (ii) using specific blends of plant-based proteins to create a more balanced amino acid profile; (iii) fortifying the plant-based protein (source) with the specific free amino acid(s) that is (are) deficient. Clinical studies are warranted to assess the anabolic properties of the various plant-derived proteins and their protein sources in vivo in humans and to identify the factors that may or may not compromise the capacity to stimulate post-prandial muscle protein synthesis rates. Such work is needed to determine whether the transition towards a more plant-based diet is accompanied by a transition towards greater dietary protein intake requirements.
Topics: Amino Acids, Essential; Animals; Dietary Proteins; Eating; Humans; Muscle Proteins; Muscle, Skeletal
PubMed: 34515966
DOI: 10.1007/s40279-021-01540-8 -
Nutrients Aug 2019Plant-sourced proteins offer environmental and health benefits, and research increasingly includes them in study formulas. However, plant-based proteins have less of an... (Review)
Review
Plant-sourced proteins offer environmental and health benefits, and research increasingly includes them in study formulas. However, plant-based proteins have less of an anabolic effect than animal proteins due to their lower digestibility, lower essential amino acid content (especially leucine), and deficiency in other essential amino acids, such as sulfur amino acids or lysine. Thus, plant amino acids are directed toward oxidation rather than used for muscle protein synthesis. In this review, we evaluate the ability of plant- versus animal-based proteins to help maintain skeletal muscle mass in healthy and especially older people and examine different nutritional strategies for improving the anabolic properties of plant-based proteins. Among these strategies, increasing protein intake has led to a positive acute postprandial muscle protein synthesis response and even positive long-term improvement in lean mass. Increasing the quality of protein intake by improving amino acid composition could also compensate for the lower anabolic potential of plant-based proteins. We evaluated and discussed four nutritional strategies for improving the amino acid composition of plant-based proteins: fortifying plant-based proteins with specific essential amino acids, selective breeding, blending several plant protein sources, and blending plant with animal-based protein sources. These nutritional approaches need to be profoundly examined in older individuals in order to optimize protein intake for this population who require a high-quality food protein intake to mitigate age-related muscle loss.
Topics: Adult; Aged; Aged, 80 and over; Amino Acids; Anabolic Agents; Animals; Dietary Proteins; Digestion; Female; Humans; Male; Middle Aged; Muscle Proteins; Muscle, Skeletal; Nutritional Physiological Phenomena; Plant Proteins; Protein Biosynthesis
PubMed: 31394788
DOI: 10.3390/nu11081825 -
Applied Physiology, Nutrition, and... Jul 2022The interest in a diet with a higher proportion of plant-based foods to animal-based foods is a global food pattern trend. However, there are concerns regarding adopting... (Review)
Review
The interest in a diet with a higher proportion of plant-based foods to animal-based foods is a global food pattern trend. However, there are concerns regarding adopting plants as the main dietary protein source to support muscle protein synthesis (MPS) and muscle mass. These concerns are centered on three issues: lower protein bioavailability due to antinutritional compounds in plants, lower per-serve scores of protein at similar energy intake, and amino acid scores of plants being lower than optimal. We aimed here to synthesize and discuss evidence around plant protein in human nutrition focusing on the capacity of these proteins to stimulate MPS as a key part of gaining or maintaining muscle mass. In this review, we addressed the issues of plant protein quality and provided evidence for how plant proteins can be made more effective to stimulate MPS and support muscle mass in partial or total replacement of consumption of products of animal origin. Plant proteins are known, in general, to have lower protein quality scores than animal proteins, and this may have important implications, especially for those aiming to increase their skeletal muscle mass through exercise. A plant-based diet has been postulated to have lower protein quality limiting MPS responses and potentially compromising exercise-induced gains in muscle mass. Current evidence shows that plant proteins can stimulate MPS, as can whole foods, especially when combining food groups, increasing portion sizes, and optimizing amino acid bioavailability through processing or common preparation methods.
Topics: Amino Acids; Animals; Dietary Proteins; Humans; Muscle Proteins; Muscle, Skeletal; Plant Proteins
PubMed: 35508011
DOI: 10.1139/apnm-2021-0806