Special Issue "Protein Intake and Muscle Mass"

A special issue of Nutrients (ISSN 2072-6643).

Deadline for manuscript submissions: closed (30 July 2019).

Special Issue Editor

Prof. Lars Holm
E-Mail Website
Guest Editor
School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, UK
Interests: protein turnover; stable isotope tracers; muscle mass; muscle strength; daily functional capability; sarcopenia

Special Issue Information

Dear colleagues,

Our understanding of the impact of protein intake for the maintenance and growth of skeletal muscle has significant improved during the last decades of research. Further, commercial interests have evolved to encompass a huge market and important industrial developments now provide targeted ingredients and foods for various purposes. Beyond discussing the needs of the general population, research has identified numerous target conditions exploring special needs with a focus on protein intake. Examples include people on hypocaloric diets with the purpose of losing fat mass, people on hypocaloric diets in extreme conditions, healthy ageing adults, geriatric patients, people suffering from COPD and with impaired kidney function, individuals undergoing rehabilitation training to restore muscle mass and function, traumatised patients at intensive care units, and people with cancer, just to mention some.

It is generally acknowledged that skeletal muscle proteins in various conditions have a low priority and are used as a reservoir of amino acids. Therefore, the muscle mass can be exposed to degradation and, after prolonged degradation, atrophy to supply amino acids for other tissues’ protein turnover and/or for metabolic substrates.

This Special Issue in Nutrients, entitled ‘Protein Intake and Muscle Mass’ welcomes reviews, viewpoints, and original papers investigating and/or commenting on the associations between dietary protein intake and the maintenance, growth, and stimulation of muscle protein mass and/or their underlying mechanisms.

Prof. Lars Holm
Guest Editor

Manuscript Submission Information

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Keywords

  • muscle mass
  • protein intake
  • peptides
  • crystalline amino acids
  • daily amount
  • meal distribution

Published Papers (5 papers)

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Research

Open AccessArticle
Native Whey Induces Similar Adaptation to Strength Training as Milk, despite Higher Levels of Leucine, in Elderly Individuals
Nutrients 2019, 11(9), 2094; https://doi.org/10.3390/nu11092094 - 04 Sep 2019
Abstract
Background: Large amounts of protein (40 g) or supplementing suboptimal servings of protein with leucine are able to overcome the anabolic resistance in elderly muscle. Our aim was to compare the effects of supplementation of native whey, high in leucine, with milk on [...] Read more.
Background: Large amounts of protein (40 g) or supplementing suboptimal servings of protein with leucine are able to overcome the anabolic resistance in elderly muscle. Our aim was to compare the effects of supplementation of native whey, high in leucine, with milk on gains in muscle mass and strength during a period of strength training, in elderly individuals. Methods: In this double-blinded, randomized, controlled study, a total of 30 healthy men and women received two daily servings of 20 g of either milk protein or native whey, during an 11-week strength training intervention. Muscle strength, lean mass, m. vastus lateralis thickness, muscle fiber area, and resting and post-exercise phosphorylation of p70S6K, 4E-BP1, and eEF-2 were assessed prior to and after the intervention period. Results: Muscle mass and strength increased, by all measures applied in both groups (p < 0.001), with no differences between groups (p > 0.25). p70S6K phosphorylation increased (~1000%, p < 0.045) 2 h after exercise in the untrained and trained state, with no differences between supplements. Total and phosphorylated mTORC-1 decreased after training. Conclusion: Supplementation with milk or native whey during an 11-week strength training period increased muscle mass and strength similarly in healthy elderly individuals. Full article
(This article belongs to the Special Issue Protein Intake and Muscle Mass)
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Open AccessFeature PaperCommunication
Mitigation of Muscle Loss in Stressed Physiology: Military Relevance
Nutrients 2019, 11(8), 1703; https://doi.org/10.3390/nu11081703 - 24 Jul 2019
Cited by 1
Abstract
Military personnel may be exposed to circumstances (e.g., large energy deficits, sleep deprivation, cognitive demands, and environmental extremes) of external stressors during training and combat operations (i.e., operational stressors) that combine to degrade muscle protein. The loss of muscle protein is further exacerbated [...] Read more.
Military personnel may be exposed to circumstances (e.g., large energy deficits, sleep deprivation, cognitive demands, and environmental extremes) of external stressors during training and combat operations (i.e., operational stressors) that combine to degrade muscle protein. The loss of muscle protein is further exacerbated by frequent periods of severe energy deficit. Exposure to these factors results in a hypogonadal state that may contribute to observed decrements in muscle mass. In this review, lessons learned from studying severe clinical stressed states and the interventions designed to mitigate the loss of muscle protein are discussed in the context of military operational stress. For example, restoration of the anabolic hormonal status (e.g., testosterone, insulin, and growth hormone) in stressed physiological states may be necessary to restore the anabolic influence derived from dietary protein on muscle. Based on our clinical experiences, restoration of the normal testosterone status during sustained periods of operational stress may be advantageous. We demonstrated that in severe burn patients, pharmacologic normalization of the anabolic hormonal status restores the anabolic stimulatory effect of nutrition on muscle by improving the protein synthetic efficiency and limiting amino acid loss from skeletal muscle. Furthermore, an optimal protein intake, and in particular essential amino acid delivery, may be an integral ingredient in a restored anabolic response during the stress state. Interventions which improve the muscle net protein balance may positively impact soldier performance in trying conditions. Full article
(This article belongs to the Special Issue Protein Intake and Muscle Mass)
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Open AccessCommunication
Dietary Protein and Muscle Mass: Translating Science to Application and Health Benefit
Nutrients 2019, 11(5), 1136; https://doi.org/10.3390/nu11051136 - 22 May 2019
Abstract
Adequate consumption of dietary protein is critical for the maintenance of optimal health during normal growth and aging. The current Recommended Dietary Allowance (RDA) for protein is defined as the minimum amount required to prevent lean body mass loss, but is often misrepresented [...] Read more.
Adequate consumption of dietary protein is critical for the maintenance of optimal health during normal growth and aging. The current Recommended Dietary Allowance (RDA) for protein is defined as the minimum amount required to prevent lean body mass loss, but is often misrepresented and misinterpreted as a recommended optimal intake. Over the past two decades, the potential muscle-related benefits achieved by consuming higher-protein diets have become increasingly clear. Despite greater awareness of how higher-protein diets might be advantageous for muscle mass, actual dietary patterns, particularly as they pertain to protein, have remained relatively unchanged in American adults. This lack of change may, in part, result from confusion over the purported detrimental effects of higher-protein diets. This manuscript will highlight common perceptions and benefits of dietary protein on muscle mass, address misperceptions related to higher-protein diets, and comment on the translation of academic advances to real-life application and health benefit. Given the vast research evidence supporting the positive effects of dietary protein intake on optimal health, we encourage critical evaluation of current protein intake recommendations and responsible representation and application of the RDA as a minimum protein requirement rather than one determined to optimally meet the needs of the population. Full article
(This article belongs to the Special Issue Protein Intake and Muscle Mass)
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Open AccessArticle
Human Muscle Protein Synthesis Rates after Intake of Hydrolyzed Porcine-Derived and Cows’ Milk Whey Proteins—A Randomized Controlled Trial
Nutrients 2019, 11(5), 989; https://doi.org/10.3390/nu11050989 - 30 Apr 2019
Cited by 1
Abstract
Background: Whey protein has been shown to be one of the best proteins to stimulate muscle protein synthesis rate (MPS), but other high quality proteins, e.g., animal/porcine-derived, could have similar effects. Objective: To investigate the effects of hydrolyzed porcine proteins from blood (HPB) [...] Read more.
Background: Whey protein has been shown to be one of the best proteins to stimulate muscle protein synthesis rate (MPS), but other high quality proteins, e.g., animal/porcine-derived, could have similar effects. Objective: To investigate the effects of hydrolyzed porcine proteins from blood (HPB) and muscle (HPM), in comparison to hydrolyzed whey protein (HW), on MPS after intake of 15 g alone or 30 g protein as part of a mixed meal. We hypothesized that the postprandial MPS would be similar for porcine proteins and whey protein. Design: Eighteen men (mean ± SD age: 24 ± 1 year; BMI: 21.7 ± 0.4 kg/m2) participated in the randomized, double-blind, three-way cross-over study. Subjects consumed the three test products (HPB, HPM and HW) in a random order in two servings at each test day. Serving 1 consisted of a drink with 15 g protein and serving 2 of a drink with 30 g protein together with a mixed meal. A flood-primed continuous infusion of (ring-13C6) phenylalanine was performed and muscle biopsies, blood and urine samples were collected for determination of MPS, muscle free leucine, plasma amino acid concentrations and urea excretion. Results: There were no statistical differences between the MPS measured after consuming 15 g protein alone or 30 g with a mixed meal (p = 0.53) of HPB (0.048 ± 0.007 vs. 0.049 ± 0.008%/h, resp.), HPM (0.063 ± 0.011 vs. 0.062 ± 0.011 %/h, resp.) and HW (0.058 ± 0.007 vs. 0.071 ± 0.013%/h, resp.). However, the impact of protein type on MPS reached statistical tendency (HPB vs. HPM (p = 0.093) and HPB vs. HW (p = 0.067)) with no difference between HPM and HW (p = 0.88). Plasma leucine, branched-chain, essential and total amino acids were generally higher for HPB and HW than HPM (p < 0.01), which reflected their content in the proteins. Muscle-free leucine was higher for HPB than HW and HPM (p < 0.05). Conclusion: Hydrolyzed porcine proteins from blood and muscle resulted in an MPS similar to that of HW, although with a trend for porcine blood proteins to be inferior to muscle proteins and whey. Consequently, these porcine-derived muscle proteins can be used similarly to whey protein to support maintenance of skeletal muscle as part of supplements and ingredients in foods. Full article
(This article belongs to the Special Issue Protein Intake and Muscle Mass)
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Open AccessArticle
Association of Protein Intake in Three Meals with Muscle Mass in Healthy Young Subjects: A Cross-Sectional Study
Nutrients 2019, 11(3), 612; https://doi.org/10.3390/nu11030612 - 13 Mar 2019
Abstract
Protein intake of >0.24 g/kg of body weight (BW) at a single meal is necessary to maximize muscle protein synthesis in a young population. However, the association between the protein intake rate for three meals and muscle mass in the young population has [...] Read more.
Protein intake of >0.24 g/kg of body weight (BW) at a single meal is necessary to maximize muscle protein synthesis in a young population. However, the association between the protein intake rate for three meals and muscle mass in the young population has not been evaluated. We hypothesized that a protein intake of >0.24 g/kg BW at all three meals is effective for maintaining muscle mass. Therefore, we cross-sectionally examined the association between protein intake at all three meals with muscle mass in 266 healthy young subjects (aged 21.4 ± 2.4 years). Subjects were divided into the AP group, which achieved protein intake >0.24 g/kg BW at all three meals; and the NP group, which did not. We calculated total fat-free mass (FFM) and appendicular fat-free mass (AppFFM) with dual-energy X-ray absorptiometry, and the percentage of total FFM (TotalFFM%) and appendicular FFM (AppFFM%) were calculated as the percentage of BW (%BW). We demonstrated that TotalFFM% (77.0 ± 0.5 vs. 75.2 ± 0.4%, p = 0.008) and AppFFM% (34.7 ± 0.3 vs. 34.1 ± 0.2%, p = 0.058) were higher in the AP than in the NP group. This finding suggests that achieving protein intake of >0.24 g/kg BW at all three meals is important for muscle mass maintenance in young populations. Full article
(This article belongs to the Special Issue Protein Intake and Muscle Mass)
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