Soy versus whey protein bars: effects on exercise training impact on lean body mass and antioxidant status

Common questions and misconceptions about protein supplementation: what does the scientific evidence really show?

Protein supplementation often refers to increasing the intake of this particular macronutrient through dietary supplements in the form of powders, ready-to-drink shakes, and bars. The primary purpose of protein supplementation is to augment dietary protein intake, aiding individuals in meeting their protein requirements, especially when it may be challenging to do so through regular food (i.e. chicken, beef, fish, pork, etc.) sources alone. A large body of evidence shows that protein has an important role in exercising and sedentary individuals. A PubMed search of "protein and exercise performance" reveals thousands of publications. Despite the considerable volume of evidence, it is somewhat surprising that several persistent questions and misconceptions about protein exist. The following are addressed: 1) Is protein harmful to your kidneys? 2) Does consuming "excess" protein increase fat mass? 3) Can dietary protein have a harmful effect on bone health? 4) Can vegans and vegetarians consume enough protein to support training adaptations? 5) Is cheese or peanut butter a good protein source? 6) Does consuming meat (i.e., animal protein) cause unfavorable health outcomes? 7) Do you need protein if you are not physically active? 8) Do you need to consume protein ≤ 1 hour following resistance training sessions to create an anabolic environment in skeletal muscle? 9) Do endurance athletes need additional protein? 10) Does one need protein supplements to meet the daily requirements of exercise-trained individuals? 11) Is there a limit to how much protein one can consume in a single meal? To address these questions, we have conducted a thorough scientific assessment of the literature concerning protein supplementation.

Metabolomics insights of conventional and organic tempe during in vitro digestion and their antioxidant properties and cytotoxicity in HCT-116 cells

Tempe, a fermented soybean food rich in polyphenols including isoflavones, is valued for its health benefits, notably its antioxidants. Concerns about glyphosate residues in crops have led to increased demand for organic soy products, including tempe. The study aimed to investigate the metabolomic profiles of tempe and its bioactive potentials prior to and following in vitro simulated gastrointestinal digestion. Conventional soybean (CS), conventional tempe (CT), conventional tempe digesta (CTD), organic soybean (OS), organic tempe (OT) and organic tempe digesta (OTD) were analysed for various assays. The study observed a significant decrease in the total phenolic and flavonoid levels for conventional and organic samples in tempe extracts (CT, OT) compared to tempe digesta (CTD, OTD). Organic tempe digesta has a higher total phenolic content (CTD = 22.55 µg GAE/g, OTD = 41.36 µg GAE/g) and flavonoid content (CTD = 4.64 µg QE/g, OTD = 10.06 µg QE/g) compared to conventional tempe digesta. However, there is a significant difference in the bioaccessibility of phenolic (CT = 74.77 %, OT = 59.20 %) and flavonoid (CT = 49.4 %, OT = 57.52 %) in both organic and conventional tempe. Tempe consistently surpasses soybean in antioxidant assays such as DPPH, ABTS, and FRAP. Organic tempe digesta exhibits the most elevated levels of antioxidants. Using GNPS and the SIRIUS database, 34 metabolites were annotated according to the criteria of having a VIP score > 1.5, a log2(FC) > 1, and a p-value < 0.05. From the list, 26 metabolites demonstrated a positive correlation with antioxidant activity, DPPH, and FRAP. Molecular networking enables the visualization of 12 prominent isoflavones, namely daidzein, daidzin, genistein, genistin, glycitein, glycitin, 6″-O-malonyldaidzin, 6″-O-acetylgenistin, 6″-O-acetyldaidzin, and 7,8,4'-trihydroxyisoflavone. Interestingly, aglycone isoflavones are abundant in organic tempe digesta while glycoside isoflavones are abundant in organic and conventional soybeans. Overall, the findings indicate that tempe digesta exhibits distinct metabolic patterns and bioactive potentials.

Efficacy of a dietary supplement derived from five edible plants on telomere length in Thai adults: A randomized, double-blind, placebo-controlled trial

Mylife/Mylife100® is a dietary supplement consisting of black sesame seed, guava fruit, mangosteen aril, pennywort leaves, and soy protein. These edible plants contain multiple high-potential bioactive compounds exerting various vital biological functions including antioxidants which contribute to delaying the rate of telomere shortening. Telomere length is associated with cellular aging and age-related diseases. This study aimed to assess the efficacy of Mylife/Mylife100® on telomere length through a randomized, double-blind placebo-controlled trial. The trial assessed the alteration of leukocyte telomere length after 32 adults aged 50-65 years received either Mylife/Mylife100® or placebo (five capsules/day) for 8-week supplementation. The results demonstrated a significant increase in mean telomere length from baseline (6313 bp) to the 8-week supplementation period (6655 bp; p < 0.05) in the group receiving the product, whereas no significant change was observed in the placebo group. Additionally, the product group exhibited a significant improvement in plasma total antioxidant capacity levels compared to the placebo group (mean change, +35 vs -38; p = 0.006). This study also showed a significant correlation between telomere length and % CD4 + T cells (r = +0.325; p = 0.00003), % CD8 + T cells (r = +0.156; p = 0.048), and visceral fat (r = - 0.349; p = 0.000006). The findings suggest that consuming this dietary supplement (Mylife/Mylife100®) for 8 weeks has a positive effect on cellular aging by lengthening telomeres possible through their antioxidant capacities. Oxidative stress and cellular aging are underlying predisease mechanisms that might be alleviated by supplementing with this product.

Effect of Soy Protein Supplementation on Muscle Adaptations, Metabolic and Antioxidant Status, Hormonal Response, and Exercise Performance of Active Individuals and Athletes: A Systematic Review of Randomised Controlled Trials

BACKGROUND

Protein supplements are important to maintain optimum health and physical performance, particularly in athletes and active individuals to repair and rebuild their skeletal muscles and connective tissues. Soy protein (SP) has gained popularity in recent years as an alternative to animal proteins.

OBJECTIVES

This systematic review evaluates the evidence from randomised controlled clinical trials of the effects of SP supplementation in active individuals and athletes in terms of muscle adaptations, metabolic and antioxidant status, hormonal response and exercise performance. It also explores the differences in SP supplementation effects in comparison to whey protein.

METHODS

A systematic search was conducted in PubMed, Embase and Web of Science, as well as a manual search in Google Scholar and EBSCO, on 27 June 2023. Randomised controlled trials that evaluated the applications of SPs supplementation on sports and athletic-related outcomes that are linked with exercise performance, adaptations and biomarkers in athletes and physically active adolescents and young adults (14 to 39 years old) were included, otherwise, studies were excluded. The risk of bias was assessed according to Cochrane's revised risk of bias tool.

RESULTS

A total of 19 eligible original research articles were included that investigated the effect of SP supplementation on muscle adaptations (n = 9), metabolic and antioxidant status (n = 6), hormonal response (n = 6) and exercise performance (n = 6). Some studies investigated more than one effect. SP was found to provide identical increases in lean mass compared to whey in some studies. SP consumption promoted the reduction of exercise-induced metabolic/blood circulating biomarkers such as triglycerides, uric acid and lactate. Better antioxidant capacity against oxidative stress has been seen with respect to whey protein in long-term studies. Some studies reported testosterone and cortisol fluctuations related to SP; however, more research is required. All studies on SP and endurance performance suggested the potential beneficial effects of SP supplementation (10-53.3 g) on exercise performance by improving high-intensity and high-speed running performance, enhancing maximal cardiac output, delaying fatigue and improving isometric muscle strength, improving endurance in recreational cyclists, increasing running velocity and decreasing accumulated lactate levels; however, studies determining the efficacy of soy protein on VO2max provided conflicted results.

CONCLUSION

It is possible to recommend SP to athletes and active individuals in place of conventional protein supplements by assessing their dosage and effectiveness in relation to different types of training. SP may enhance lean mass compared with other protein sources, enhance the antioxidant status, and reduce oxidative stress. SP supplementation had an inconsistent effect on testosterone and cortisol levels. SP supplementation may be beneficial, especially after muscle damage, high-intensity/high-speed or repeated bouts of strenuous exercise.

Bioactive milk peptides: an updated comprehensive overview and database

Partial digestion of milk proteins leads to the formation of numerous bioactive peptides. Previously, our research team thoroughly examined the decades of existing literature on milk bioactive peptides across species to construct the milk bioactive peptide database (MBPDB). Herein, we provide a comprehensive update to the data within the MBPDB and a review of the current state of research for each functional category from in vitro to animal and clinical studies, including angiotensin-converting enzyme (ACE)-inhibitory, antimicrobial, antioxidant, dipeptidyl peptidase (DPP)-IV inhibitory, opioid, anti-inflammatory, immunomodulatory, calcium absorption and bone health and anticancer activity. This information will help drive future research on the bioactivities of milk peptides.

Nutritional Considerations for the Vegan Athlete

Accepting a continued rise in the prevalence of vegan-type diets in the general population is also likely to occur in athletic populations, it is of importance to assess the potential impact on athletic performance, adaptation, and recovery. Nutritional consideration for the athlete requires optimization of energy, macronutrient, and micronutrient intakes, and potentially the judicious selection of dietary supplements, all specified to meet the individual athlete's training and performance goals. The purpose of this review is to assess whether adopting a vegan diet is likely to impinge on such optimal nutrition and, where so, consider evidence based yet practical and pragmatic nutritional recommendations. Current evidence does not support that a vegan-type diet will enhance performance, adaptation, or recovery in athletes, but equally suggests that an athlete can follow a (more) vegan diet without detriment. A clear caveat, however, is that vegan diets consumed spontaneously may induce suboptimal intakes of key nutrients, most notably quantity and/or quality of dietary protein and specific micronutrients (eg, iron, calcium, vitamin B12, and vitamin D). As such, optimal vegan sports nutrition requires (more) careful consideration, evaluation, and planning. Individual/seasonal goals, training modalities, athlete type, and sensory/cultural/ethical preferences, among other factors, should all be considered when planning and adopting a vegan diet.

Vitamin D as a Shield against Aging

Aging can be seen as a physiological progression of biomolecular damage and the accumulation of defective cellular components, which trigger and amplify the process, toward whole-body function weakening. Senescence initiates at the cellular level and consists in an inability to maintain homeostasis, characterized by the overexpression/aberrant expression of inflammatory/immune/stress responses. Aging is associated with significant modifications in immune system cells, toward a decline in immunosurveillance, which, in turn, leads to chronic elevation of inflammation/oxidative stress, increasing the risk of (co)morbidities. Albeit aging is a natural and unavoidable process, it can be regulated by some factors, like lifestyle and diet. Nutrition, indeed, tackles the mechanisms underlying molecular/cellular aging. Many micronutrients, i.e., vitamins and elements, can impact cell function. This review focuses on the role exerted by vitamin D in geroprotection, based on its ability to shape cellular/intracellular processes and drive the immune response toward immune protection against infections and age-related diseases. To this aim, the main biomolecular paths underlying immunosenescence and inflammaging are identified as biotargets of vitamin D. Topics such as heart and skeletal muscle cell function/dysfunction, depending on vitamin D status, are addressed, with comments on hypovitaminosis D correction by food and supplementation. Albeit research has progressed, still limitations exist in translating knowledge into clinical practice, making it necessary to focus attention on the role of vitamin D in aging, especially considering the growing number of older individuals.

Whey protein and soy protein prevent obesity by upregulating uncoupling protein 1 to activate brown adipose tissue and promote white adipose tissue browning in high-fat diet-fed mice

There are inconsistent conclusions regarding the effect of whey protein and soy protein supplementation on obesity, and the underlying mechanisms of a high-protein diet for reducing weight gain remain to be elucidated. The aim of the present study was to investigate the preventive effect of whey protein and soy protein on obesity and its possible mechanism. Eighty-four male C57BL/6J mice were randomly divided into seven dietary groups: control group (10% fat) and 6 groups fed with a high-fat diet (HFD): 10% whey protein isolate (WPI), 20% WPI, 30% WPI, 10% soy protein isolate (SPI), 20% SPI and 30% SPI for 12 weeks. Compared with the 20% SPI group, the 20% WPI group had a significantly lower body weight, serum levels of insulin, total cholesterol and leptin, weight of inguinal white adipose tissue (iWAT), and size of adipocytes in iWAT and epididymal white adipose tissue (eWAT). The body mass index (BMI) and the Lee index were significantly lower in the WPI groups than those in the SPI groups at the same protein level. The body weight, body weight gain and BMI were significantly lower with the decreasing ratio of protein to carbohydrate (P/C). Compared with the 20% SPI group, the expressions of browning-related genes such as UCP1 (uncoupling protein 1), PGC-1α, AMPKα and Cidea and the protein expression of UCP1 were significantly higher in brown adipose tissue (BAT) and iWAT in the 20% WPI group. Moreover, the expressions of lipogenesis-related genes such as SREBP1c, PPARγ, LPL and DGAT1 in BAT, iWAT and eWAT in the 10% WPI group were significantly lower compared with the 10% SPI group. In conclusion, whey protein was more effective than soy protein in preventing obesity in mice, probably by suppressing lipogenesis in adipose tissues, activating BAT and promoting the browning of iWAT. In addition, lowering the P/C ratio was beneficial for combating obesity in the context of a HFD.

Systematic review and meta-analysis of protein intake to support muscle mass and function in healthy adults

We performed a systematic review, meta-analysis, and meta-regression to determine if increasing daily protein ingestion contributes to gaining lean body mass (LBM), muscle strength, and physical/functional test performance in healthy subjects. A protocol for the present study was registered (PROSPERO, CRD42020159001), and a systematic search of Medline, Embase, CINAHL, and Web of Sciences databases was undertaken. Only randomized controlled trials (RCT) where participants increased their daily protein intake and were healthy and non-obese adults were included. Research questions focused on the main effects on the outcomes of interest and subgroup analysis, splitting the studies by participation in a resistance exercise (RE), age (<65 or ≥65 years old), and levels of daily protein ingestion. Three-level random-effects meta-analyses and meta-regressions were conducted on data from 74 RCT. Most of the selected studies tested the effects of additional protein ingestion during RE training. The evidence suggests that increasing daily protein ingestion may enhance gains in LBM in studies enrolling subjects in RE (SMD [standardized mean difference] = 0.22, 95% CI [95% confidence interval] 0.14:0.30, P < 0.01, 62 studies, moderate level of evidence). The effect on LBM was significant in subjects ≥65 years old ingesting 1.2-1.59 g of protein/kg/day and for younger subjects (<65 years old) ingesting ≥1.6 g of protein/kg/day submitted to RE. Lower-body strength gain was slightly higher by additional protein ingestion at ≥1.6 g of protein/kg/day during RE training (SMD = 0.40, 95% CI 0.09:0.35, P < 0.01, 19 studies, low level of evidence). Bench press strength is slightly increased by ingesting more protein in <65 years old subjects during RE training (SMD = 0.18, 95% CI 0.03:0.33, P = 0.01, 32 studies, low level of evidence). The effects of ingesting more protein are unclear when assessing handgrip strength and only marginal for performance in physical function tests. In conclusion, increasing daily protein ingestion results in small additional gains in LBM and lower body muscle strength gains in healthy adults enrolled in resistance exercise training. There is a slight effect on bench press strength and minimal effect performance in physical function tests. The effect on handgrip strength is unclear.

An association between the physical activity level and skeletal muscle mass index in female university students with a past exercise habituation

OBJECTIVES

This study aims to investigate the association between skeletal muscle mass index (SMI) and physical activity among female university students who had exercise habituation in junior and high school.

METHODS

The body composition of 120 Japanese female students was measured using the bioelectrical impedance analysis (BIA) method, and their physical activity level (PAL) was measured using a factorial method. Based on the 'Dietary Reference Intakes for Japanese' (DRIs-J), according to the Ministry of Health, Labour and Welfare, PAL (24-h energy consumption/basal metabolic rate) classifications were defined as low-PAL (PAL < 1.6), moderate-PAL (1.6 ≤ PAL < 1.9), and high-PAL (1.9 ≤ PAL < 2.2), respectively.

RESULTS

Individuals with low-PAL had a significantly lower SMI, especially for the lower limb muscles, than individuals with moderate-PAL or higher. More than 50% of the individuals with currently low-PAL corresponded or tended to correspond to the SMI cut-off value defined by the Asian Working Group for Sarcopenia or the 2017 National Health and Nutrition Survey of Japan. Therefore, more than half of the female students with currently low-PAL, even those with an exercise habituation in the past, corresponded to the cut-off value for muscle loss in sarcopenia diagnosis, particularly in the lower limbs.

CONCLUSIONS

These results suggest that it is important to maintain a moderate or higher level of physical activity in the DRIs-J classification, even for young women who used to exercise in the past, to maintain muscle mass accordingly.

Pea Proteins Have Anabolic Effects Comparable to Milk Proteins on Whole Body Protein Retention and Muscle Protein Metabolism in Old Rats

Plant proteins are attracting rising interest due to their pro-health benefits and environmental sustainability. However, little is known about the nutritional value of pea proteins when consumed by older people. Herein, we evaluated the digestibility and nutritional efficiency of pea proteins compared to casein and whey proteins in old rats. Thirty 20-month-old male Wistar rats were assigned to an isoproteic and isocaloric diet containing either casein (CAS), soluble milk protein (WHEY) or Pisane™ pea protein isolate for 16 weeks. The three proteins had a similar effect on nitrogen balance, true digestibility and net protein utilization in old rats, which means that different protein sources did not alter body composition, tissue weight, skeletal muscle protein synthesis or degradation. Muscle mitochondrial activity, inflammation status and insulin resistance were similar between the three groups. In conclusion, old rats used pea protein with the same efficiency as casein or whey proteins, due to its high digestibility and amino acid composition. Using these plant-based proteins could help older people diversify their protein sources and more easily achieve nutritional intake recommendations.

Plant Proteins and Exercise: What Role Can Plant Proteins Have in Promoting Adaptations to Exercise?

Adequate dietary protein is important for many aspects of health with current evidence suggesting that exercising individuals need greater amounts of protein. When assessing protein quality, animal sources of protein routinely rank amongst the highest in quality, largely due to the higher levels of essential amino acids they possess in addition to exhibiting more favorable levels of digestibility and absorption patterns of the amino acids. In recent years, the inclusion of plant protein sources in the diet has grown and evidence continues to accumulate on the comparison of various plant protein sources and animal protein sources in their ability to stimulate muscle protein synthesis (MPS), heighten exercise training adaptations, and facilitate recovery from exercise. Without question, the most robust changes in MPS come from efficacious doses of a whey protein isolate, but several studies have highlighted the successful ability of different plant sources to significantly elevate resting rates of MPS. In terms of facilitating prolonged adaptations to exercise training, multiple studies have indicated that a dose of plant protein that offers enough essential amino acids, especially leucine, consumed over 8–12 weeks can stimulate similar adaptations as seen with animal protein sources. More research is needed to see if longer supplementation periods maintain equivalence between the protein sources. Several practices exist whereby the anabolic potential of a plant protein source can be improved and generally, more research is needed to best understand which practice (if any) offers notable advantages. In conclusion, as one considers the favorable health implications of increasing plant intake as well as environmental sustainability, the interest in consuming more plant proteins will continue to be present. The evidence base for plant proteins in exercising individuals has seen impressive growth with many of these findings now indicating that consumption of a plant protein source in an efficacious dose (typically larger than an animal protein) can instigate similar and favorable changes in amino acid update, MPS rates, and exercise training adaptations such as strength and body composition as well as recovery.

Comparison of the effect of soya protein and whey protein on body composition: a meta-analysis of randomised clinical trials

Essential amino acids (EAA) promote the process of regulating muscle synthesis. Thus, whey protein that contains higher amounts of EAA can have a considerable effect on modifying muscle synthesis. However, there is insufficient evidence regarding the effect of soya and whey protein supplementation on body composition. Thus, we sought to perform a meta-analysis of published randomised clinical trials that examined the effect of whey protein supplementation and soya protein supplementation on body composition (lean body mass, fat mass, body mass and body fat percentage) in adults. We searched PubMed, Scopus and Google Scholar, up to August 2020, for all relevant published articles assessing soya protein supplementation and whey protein supplementation on body composition parameters. We included all randomised clinical trials that investigated the effect of whey protein supplementation and soya protein supplementation on body composition in adults. Pooled means and standard deviations were calculated using random effects models. Subgroup analysis was applied to discern possible sources of heterogeneity. After excluding non-relevant articles, ten studies, with 596 participants, remained in this study. We found a significant increase in lean body mass after whey protein supplementation (weighted mean difference (WMD: 0·91; 95 % CI 0·15, 1·67; P = 0·019). We observed no significant change between whey protein supplementation and body mass, fat mass and body fat percentage. We found no significant change between soya protein supplementation and body composition parameters. Whey protein supplementation significantly improved body composition via increases in lean body mass, without influencing fat mass, body mass and body fat percentage.

Protein Source and Quality for Skeletal Muscle Anabolism in Young and Older Adults: A Systematic Review and Meta-Analysis

BACKGROUND

There is much debate regarding the source/quality of dietary proteins in supporting indices of skeletal muscle anabolism.

OBJECTIVE

We performed a systematic review and meta-analysis to determine the effect of protein source/quality on acute muscle protein synthesis (MPS) and changes in lean body mass (LBM) and strength, when combined with resistance exercise (RE).

METHODS

A systematic search of the literature was conducted to identify studies that compared the effects of ≥2 dose-matched, predominantly isolated protein sources of varying "quality." Three separate models were employed as follows: 1) protein feeding alone on MPS, 2) protein feeding combined with a bout of RE on MPS, and 3) protein feeding combined with longer-term resistance exercise training (RET) on LBM and strength. Further subgroup analyses were performed to compare the effects of protein source/quality between young and older adults. A total of 27 studies in young (18-35 y) and older (≥60 y) adults were included.

RESULTS

Analysis revealed an effect favoring higher-quality protein for postprandial MPS at rest [mean difference (MD): 0.014%/h; 95% CI: 0.006, 0.021; P < 0.001] and following RE (MD: 0.022%/h; 95% CI: 0.014, 0.030; P < 0.00001) in young (model 1: 0.016%/h; 95% CI: -0.004, 0.036; P = 0.12; model 2: 0.030%/h; 95% CI: 0.015, 0.045; P < 0.0001) and older (model 1: 0.012%/h; 95% CI: 0.006, 0.018; P < 0.001; model 2: 0.014%/h; 95% CI: 0.007, 0.021; P < 0.001) adults. However, although higher protein quality was associated with superior strength gains with RET [standardized mean difference (SMD): 0.24 kg; 95% CI: 0.02, 0.45; P = 0.03)], no effect was observed on changes to LBM (SMD: 0.05 kg; 95% CI: -0.16, 0.25; P = 0.65).

CONCLUSIONS

The current review suggests that protein quality may provide a small but significant impact on indices of muscle protein anabolism in young and older adults. However, further research is warranted to elucidate the importance of protein source/quality on musculoskeletal aging, particularly in situations of low protein intake.

Protein Source and Muscle Health in Older Adults: A Literature Review

Research shows that higher dietary protein of up to 1.2 g/kg_bodyweight/day may help prevent sarcopenia and maintain musculoskeletal health in older individuals. Achieving higher daily dietary protein levels is challenging, particularly for older adults with declining appetites and underlying health conditions. The negative impact of these limitations on aging muscle may be circumvented through the consumption of high-quality sources of protein and/or supplementation. Currently, there is a debate regarding whether source of protein differentially affects musculoskeletal health in older adults. Whey and soy protein have been used as the most common high-quality proteins in recent literature. However, there is growing consumer demand for additional plant-sourced dietary protein options. For example, pea protein is rapidly gaining popularity among consumers, despite little to no research regarding its long-term impact on muscle health. Therefore, the objectives of this review are to: (1) review current literature from the past decade evaluating whether specific source(s) of dietary protein provide maximum benefit to muscle health in older adults; and (2) highlight the need for future research specific to underrepresented plant protein sources, such as pea protein, to then provide clearer messaging surrounding plant-sourced versus animal-sourced protein and their effects on the aging musculoskeletal system.

Effects of daily 24-gram doses of rice or whey protein on resistance training adaptations in trained males

BACKGROUND

Large (48-g), isonitrogenous doses of rice and whey protein have previously been shown to stimulate similar adaptations to resistance training, but the impact of consuming smaller doses has yet to be compared. We evaluated the ability of 24-g doses of rice or whey protein concentrate to augment adaptations following 8 weeks of resistance training.

METHODS

Healthy resistance-trained males (n = 24, 32.8 ± 6.7 years, 179.3 ± 8.5 cm, 87.4 ± 8.5 kg, 27.2 ± 1.9 kg/m², 27.8 ± 6.0% fat) were randomly assigned and matched according to fat-free mass to consume 24-g doses of rice (n = 12, Growing Naturals, LLC) or whey (n = 12, NutraBio Labs, Inc.) protein concentrate for 8 weeks while completing a standardized resistance training program. Body composition (DXA), muscular strength (one-repetition maximum [1RM]) and endurance (repetitions to fatigue [RTF] at 80% 1RM) using bench press (BP) and leg press (LP) exercises along with anaerobic capacity (Wingate) were assessed before and after the intervention. Subjects were asked to maintain regular dietary habits and record dietary intake every 2 weeks. Outcomes were assessed using 2 × 2 mixed (group x time) factorial ANOVA with repeated measures on time and independent samples t-tests using the change scores from baseline. A p-value of 0.05 and 95% confidence intervals on the changes between groups were used to determine outcomes.

RESULTS

No baseline differences (p > 0.05) were found for key body composition and performance outcomes. No changes (p > 0.05) in dietary status occurred within or between groups (34 ± 4 kcal/kg/day, 3.7 ± 0.77 g/kg/day, 1.31 ± 0.28 g/kg/day, 1.87 ± 0.23 g/kg/day) throughout the study for daily relative energy (34 ± 4 kcals/kg/day), carbohydrate (3.7 ± 0.77 g/kg/day), fat (1.31 ± 0.28 g/kg/day), and protein (1.87 ± 0.23 g/kg/day) intake. Significant main effects for time were revealed for body mass (p = 0.02), total body water (p = 0.01), lean mass (p = 0.008), fat-free mass (p = 0.007), BP 1RM (p = 0.02), BP volume (p = 0.04), and LP 1RM (p = 0.01). Changes between groups were similar for body mass (- 0.88, 2.03 kg, p = 0.42), fat-free mass (- 0.68, 1.99 kg, p = 0.32), lean mass (- 0.73, 1.91 kg, p = 0.37), fat mass (- 0.48, 1.02 kg, p = 0.46), and % fat (- 0.63, 0.71%, p = 0.90). No significant between group differences were seen for BP 1RM (- 13.8, 7.1 kg, p = 0.51), LP 1RM (- 38.8, 49.6 kg, p = 0.80), BP RTF (- 2.02, 0.35 reps, p = 0.16), LP RTF (- 1.7, 3.3 reps, p = 0.50), and Wingate peak power (- 72.5, 53.4 watts, p = 0.76) following the eight-week supplementation period.

CONCLUSIONS

Eight weeks of daily isonitrogenous 24-g doses of rice or whey protein in combination with an eight-week resistance training program led to similar changes in body composition and performance outcomes. Retroactively registered on as NCT04411173 .

The Antioxidant Role of Soy and Soy Foods in Human Health

Oxidative stress seems to play a role in many chronic diseases, such as cardiovascular diseases, diabetes, and some cancers. Research is always looking for effective approaches in the prevention and treatment of these pathologies with safe strategies. Given the central role of nutrition, the identification of beneficial healthy foods can be the best key to having a safe and at the same time effective approach. Soy has always aroused great scientific interest but often this attention is galvanized by the interaction with estrogen receptors and related consequences on health. However, soy, soy foods, and soy bioactive substances seem to have antioxidant properties, suggesting their role in quenching reactive oxygen species, although it was frequently mentioned but not studied in depth. The purpose of this review is to summarize the scientific evidence of the antioxidant properties of soy by identifying the human clinical trials available in the literature. A total of 58 manuscripts were individuated through the literature search for the final synthesis. Soy bioactive substances involved in redox processes appear to be multiple and their use seems promising. Other larger clinical trials with adequate standardization and adequate choice of biomarkers will fill the gap currently existing on the suggestive role of soy in antioxidant mechanisms.

No Significant Differences in Muscle Growth and Strength Development When Consuming Soy and Whey Protein Supplements Matched for Leucine Following a 12 Week Resistance Training Program in Men and Women: A Randomized Trial

There are conflicting reports regarding the efficacy of plant versus animal-derived protein to support muscle and strength development with resistance training. The purpose of this study was to determine whether soy and whey protein supplements matched for leucine would comparably support strength increases and muscle growth following 12 weeks of resistance training. Sixty-one untrained young men (n = 19) and women (n = 42) (18-35 year) enrolled in this study, and 48 completed the trial (17 men, 31 women). All participants engaged in supervised resistance training 3×/week and consumed 19 grams of whey protein isolate or 26 grams of soy protein isolate, both containing 2 g (grams) of leucine. Multi-level modeling indicated that total body mass (0.68 kg; 95% CI: 0.08, 1.29 kg; p < 0.001), lean body mass (1.54 kg; 95% CI: 0.94, 2.15 kg; p < 0.001), and peak torque of leg extensors (40.27 Nm; 95% CI: 28.98, 51.57 Nm, p < 0.001) and flexors (20.44 Nm; 95% CI: 12.10, 28.79 Nm; p < 0.001) increased in both groups. Vastus lateralis muscle thickness tended to increase, but this did not reach statistical significance (0.12 cm; 95% CI: -0.01, 0.26 cm; p = 0.08). No differences between groups were observed (p > 0.05). These data indicate that increases in lean mass and strength in untrained participants are comparable when strength training and supplementing with soy or whey matched for leucine.

Targeting Age-Dependent Functional and Metabolic Decline of Human Skeletal Muscle: The Geroprotective Role of Exercise, Myokine IL-6, and Vitamin D

In the elderly, whole-body health largely relies on healthy skeletal muscle, which controls body stability, locomotion, and metabolic homeostasis. Age-related skeletal muscle structural/functional deterioration is associated with a higher risk of severe comorbid conditions and poorer outcomes, demanding major socioeconomic costs. Thus, the need for efficient so-called geroprotective strategies to improve resilience and ensure a good quality of life in older subjects is urgent. Skeletal muscle senescence and metabolic dysregulation share common cellular/intracellular mechanisms, potentially representing targets for intervention to preserve muscle integrity. Many factors converge in aging, and multifaceted approaches have been proposed as interventions, although they have often been inconclusive. Physical exercise can counteract aging and metabolic deficits, not only in maintaining tissue mass, but also by preserving tissue secretory function. Indeed, skeletal muscle is currently considered a proper secretory organ controlling distant organ functions through immunoactive regulatory small peptides called myokines. This review provides a current perspective on the main biomolecular mechanisms underlying age-dependent and metabolic deterioration of skeletal muscle, herein discussed as a secretory organ, the functional integrity of which largely depends on exercise and myokine release. In particular, muscle-derived interleukin (IL)-6 is discussed as a nutrient-level biosensor. Overall, exercise and vitamin D are addressed as optimal geroprotective strategies in view of their multi-target effects.

Comparison of the Effects of Soy Protein and Whey Protein Supplementation during Exercise: a Systematic Review

AbstractThe interest of the supplementation market for the soy protein consumption  to optimize physical and metabolic performance after exercise is increasing. However, evidence suggests that the  soy protein ingestion has lower anabolic properties when compared with whey protein. The purpose of this systematic review was to compare the effects of whey protein and soy protein supplementation on the  muscle functions maintenance after exercise. This review was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Articles were searched for in the Pubmed database and included studies comparing the effects of soy protein and whey protein consumption on protein synthesis, lean mass gain and oxidative stress reduction in response to endurance or resistance training. Thirteen trials were included in this review. The results showed that the whey protein consumption is superior to that of soy protein with respect to protein synthesis and lean mass gain, but soy protein showed superior results in reducing oxidative stress. Future research comparing both soy and whey protein are needed to define protein source to be used in nutritional interventions to protein synthesis, lean mass gain and oxidative stress in different populations. Keywords: Soybean Proteins. Milk Proteins. Protein Biosynthesis. Hypertrophy. ResumoO interesse do mercado de suplementação pelo consumo de proteína de soja para otimizar o desempenho físico e metabólico após o exercício está aumentando. No entanto, evidências sugerem que a ingestão da proteína de soja tem propriedades anabólicas mais baixas quando comparada à proteína do soro do leite. O objetivo desta revisão sistemática foi comparar os efeitos da suplementação com whey protein e proteína de soja na manutenção das funções musculares após o exercício. Esta revisão foi realizada usando os Itens de Relatório Preferidos para Revisões Sistemáticas e Meta-Análises (PRISMA). Os artigos foram pesquisados na base de dados Pubmed e incluíram estudos comparando os efeitos da proteína de soja e do consumo de proteínas do soro na síntese protéica, ganho de massa magra e redução do estresse oxidativo em resposta ao treinamento de resistência ou resistência. Treze ensaios foram incluídos nesta revisão. Os resultados mostraram que o consumo de proteína de soro é superior ao da proteína de soja em relação à síntese protéica e ao ganho de massa magra, mas a proteína de soja apresentou resultados superiores na redução do estresse oxidativo. Pesquisas futuras comparando a soja e a proteína do soro do leite são necessárias para definir a fonte protéica a ser usada em intervenções nutricionais para a síntese protéica, ganho de massa magra e estresse oxidativo em diferentes populações. Palavras-chave: Proteínas de Soja. Proteínas do Leite. Biossíntese de Proteínas. Hipertrofia.

No Difference between Spray Dried Milk and Native Whey Supplementation with Strength Training

Background

A rapid digestibility and high leucine content are considered important for maximal stimulation of muscle protein synthesis. Consequently, with these properties, native whey may hold greater anabolic potential than milk, when supplemented in combination with strength training. Our aim was to compare the effects of supplementation with milk or native whey, during a 12-wk strength training period, on gains in muscle mass and strength in young adults.

Methods

In this double-blinded, randomized, controlled study a total of 40 untrained young men and women received two daily servings of either milk or native whey containing 20 g of protein, during a 12-wk strength training intervention. Muscle strength, lean mass, thigh muscle cross-sectional area, m. vastus lateralis thickness and muscle fiber cross-sectional area were assessed before and after the training period. In addition, the acute phosphorylation of the anabolic kinases p70S6K, 4E-BP1 and eEF-2 in response to a standardized workout and supplementation was investigated before and after the 12-wk training period.

Results

Muscle mass and strength increased, by all measures applied (5%–16%, P < 0.001), with no differences between groups (P > 0.25). p70S6K phosphorylation increased (~1000%, P < 0.02) 2 h after exercise in the untrained and trained state, but no differences in anabolic signaling were observed between supplements (P > 0.40). No correlation between these acute measures and changes in muscle mass or strength were observed.

Conclusion

Supplementation with milk or native whey during a 12-wk strength training period did not differentially affect muscle mass and strength in young untrained individuals.

The Role of the Anabolic Properties of Plant- versus Animal-Based Protein Sources in Supporting Muscle Mass Maintenance: A Critical 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.

Effects of isolated soy protein and strength exercise training on exercise performance and biochemical profile in postpartum mice

OBJECTIVE

Postpartum women are at an increased risk for obesity and metabolic diseases because of excessive weight gain during pregnancy and weight retention after delivery. Maintenance of good nutrition and regular physical activity is used as a therapeutic approach for promotion of health and well-being in postpartum women. The aim of this study is to assess the independent and additive effects of isolated soy protein (ISP) and strength exercise training (ET) on weight management, exercise performance and health maintenance in postpartum mice.

DESIGN AND METHODS

Thirty-two postpartum mice (ICR, 14-weeks old) were divided into four groups (n = 8 per group): Group 1 mice were the sedentary control with vehicle (SC), Group 2 mice were the sedentary control with ISP supplementation (8.95 g·kg^-1, SC + ISP), Group 3 mice received vehicle with exercise training (ET) and Group 4 mice received isolated soy protein with exercise training (ISP + ET). Animals in the ET and ISP + ET groups underwent strength exercise training for 6 weeks, 5 days a week. Exercise performance was evaluated by forelimb grip strength and exhaustive swimming time, as well as by changes in body composition and biochemical parameters at the end of the experiment.

RESULTS

Combined intervention of ISP and ET increased lean muscle mass and prevented body weight and fat elevation. The grip strength and exhaustive swimming time of the ISP + ET group were significantly higher than the other groups. The ISP + ET group showed significantly decreased serum levels of lactate, ammonia and creatinine phosphate kinase (CPK), and increased glucose level after the 15-min swimming test. The serum levels of aspartate transaminase (AST), triglyceride (TG) and creatinine after sacrifice were significantly decreased in the ET + ISP group. ISP combined with ET promoted fat oxidation in brown adipose tissue (BAT) as evidenced from the increased utilization of plasma and BAT tissue triglyceride.

CONCLUSIONS

We suggest that long-term supplementation with ISP can have a wide spectrum of bioactivities on health promotion, performance improvement and fitness. ISP with ET conferred better energy utilization, improved biochemical profiles and may be an effective ergogenic aid in strength training.

Soymilk ingestion immediately after therapeutic exercise enhances rehabilitation outcomes in chronic stroke patients: A randomized controlled trial

PURPOSE

This study investigates the effects of an 8-weeks rehabilitation exercise plus soymilk ingestion immediately after exercise on functional outcomes in chronic stroke patients.

METHODS

Twenty-two stroke patients (age: 57-84 yrs; time since stroke onset: 2-19 yrs) participated and completed the study. A randomized, placebo-controlled and double-blind design was used. Participants were randomly allocated to either soymilk (SMS; n = 11) or placebo (PLA; n = 11) group and received identical 8-weeks rehabilitation intervention (3 sessions/week; 120 min/session) with corresponding treatment beverages. The physical and functional outcomes were evaluated before, during, and after the intervention.

RESULTS

The 8-weeks rehabilitation program enhanced functional outcomes of participants. The immediate soymilk ingestion after exercise additionally improved hand grip strength (p = 0.021), 8-feet walking speed (p = 0.019), walking performance per unit lean mass (p = 0.024), and 6-minute walk performance (6MWT, p = 0.016) compared with PLA after the intervention. However, the improvements in the total score for short physical performance battery (SPPB) and lean mass did not differ between groups.

CONCLUSION

Compared with rehabilitation alone, the 8-week rehabilitation program combined with immediate soymilk ingestion further improved walking speed, exercise endurance, grip strength, and muscle functionality in chronic stroke patients.

Protein content and amino acid composition of commercially available plant-based protein isolates

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.

Soy, Soy Foods and Their Role in Vegetarian Diets

Soy is a basic food ingredient of traditional Asian cuisine used for thousands of years. In Western countries, soybeans have been introduced about a hundred years ago and recently they are mainly used for surrogate foods production. Soy and soy foods are common nutritional solutions for vegetarians, due to their high protein content and versatility in the production of meat analogues and milk substitutes. However, there are some doubts about the potential effects on health, such as the effectiveness on cardiovascular risk reduction or, conversely, on the possible disruption of thyroid function and sexual hormones. The soy components that have stimulated the most research interest are isoflavones, which are polyphenols with estrogenic properties highly contained in soybeans. In this review, we discuss the characteristics of soy and soy foods, focusing on their nutrient content, including phytoestrogens and other bioactive substances that are noteworthy for vegetarians, the largest soy consumers in the Western countries. The safety of use will also be discussed, given the growing trend in adoption of vegetarian styles and the new soy-based foods availability.

A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults

OBJECTIVE

We performed a systematic review, meta-analysis and meta-regression to determine if dietary protein supplementation augments resistance exercise training (RET)-induced gains in muscle mass and strength.

DATA SOURCES

A systematic search of Medline, Embase, CINAHL and SportDiscus.

ELIGIBILITY CRITERIA

Only randomised controlled trials with RET ≥6 weeks in duration and dietary protein supplementation.

DESIGN

Random-effects meta-analyses and meta-regressions with four a priori determined covariates. Two-phase break point analysis was used to determine the relationship between total protein intake and changes in fat-free mass (FFM).

RESULTS

Data from 49 studies with 1863 participants showed that dietary protein supplementation significantly (all p<0.05) increased changes (means (95% CI)) in: strength-one-repetition-maximum (2.49 kg (0.64, 4.33)), FFM (0.30 kg (0.09, 0.52)) and muscle size-muscle fibre cross-sectional area (CSA; 310 µm² (51, 570)) and mid-femur CSA (7.2 mm² (0.20, 14.30)) during periods of prolonged RET. The impact of protein supplementation on gains in FFM was reduced with increasing age (-0.01 kg (-0.02,-0.00), p=0.002) and was more effective in resistance-trained individuals (0.75 kg (0.09, 1.40), p=0.03). Protein supplementation beyond total protein intakes of 1.62 g/kg/day resulted in no further RET-induced gains in FFM.

SUMMARY/CONCLUSION

Dietary protein supplementation significantly enhanced changes in muscle strength and size during prolonged RET in healthy adults. Increasing age reduces and training experience increases the efficacy of protein supplementation during RET. With protein supplementation, protein intakes at amounts greater than ~1.6 g/kg/day do not further contribute RET-induced gains in FFM.

Ingestion of soy–whey blended protein augments sports performance and ameliorates exercise-induced fatigue in a rat exercise model

This study sought to determine the effects of soy–whey blended protein supplementation on sports performance and related biochemical parameters after long-term training.

Inflammaging and Skeletal Muscle: Can Protein Intake Make a Difference?

Inflammaging is the chronic low-grade inflammatory state present in the elderly, characterized by increased systemic concentrations of proinflammatory cytokines. It has been shown that inflammaging increases the risk of pathologic conditions and age-related diseases, and that it also has been associated with increased skeletal muscle wasting, strength loss, and functional impairments. Experimental evidence suggests that the increased concentrations of proinflammatory cytokines and primary tumor necrosis factor α observed in chronic inflammation lead to protein degradation through proteasome activation and reduced skeletal muscle protein synthesis (MPS) via protein kinase B/Akt downregulation. Dairy and soy proteins contain all the essential amino acids, demonstrate sufficient absorption kinetics, and include other bioactive peptides that may offer nutritional benefits, in addition to those of stimulating MPS. Whey protein has antioxidative effects, primarily because of its ability to enhance the availability of reduced glutathione and the activity of the endogenous antioxidative enzyme system. Soy protein and isoflavone-enriched soy protein, meanwhile, may counteract chronic inflammation through regulation of the nuclear transcription factor κB signaling pathway and cytokine production. Although evidence suggests that whey protein, soy protein, and isoflavone-enriched soy proteins may be promising nutritional interventions against the oxidative stress and chronic inflammation present in pathologic conditions and aging (inflammaging), there is a lack of information about the anabolic potential of dietary protein intake and protein supplementation in elderly people with increased systemic inflammation. The antioxidative and anti-inflammatory effects, as well as the anabolic potential of protein supplementation, should be further investigated in the future with well-designed clinical trials focusing on inflammaging and its associated skeletal muscle loss.

Effects of Whey Protein Alone or as Part of a Multi-ingredient Formulation on Strength, Fat-Free Mass, or Lean Body Mass in Resistance-Trained Individuals: A Meta-analysis

BACKGROUND

Even though the positive effects of whey protein-containing supplements for optimizing the anabolic responses and adaptations process in resistance-trained individuals have been supported by several investigations, their use continues to be controversial. Additionally, the administration of different multi-ingredient formulations where whey proteins are combined with carbohydrates, other protein sources, creatine, and amino acids or derivatives, has been extensively proposed as an effective strategy to maximize strength and muscle mass gains in athletes.

OBJECTIVE

We aimed to systematically summarize and quantify whether whey protein-containing supplements, administered alone or as a part of a multi-ingredient, could improve the effects of resistance training on fat-free mass or lean body mass, and strength in resistance-trained individuals when compared with other iso-energetic supplements containing carbohydrates or other sources of proteins.

METHODS

A structured literature search was conducted on PubMed, Science Direct, Web of Science, Cochrane Libraries, US National Institutes of Health clinicaltrials.gov, SPORTDiscus, and Google Scholar databases. Main inclusion criteria comprised randomized controlled trial study design, adults (aged 18 years and over), resistance-trained individuals, interventions (a resistance training program for a period of 6 weeks or longer, combined with whey protein supplementation administered alone or as a part of a multi-ingredient), and a calorie equivalent contrast supplement from carbohydrates or other non-whey protein sources. Continuous data on fat-free mass and lean body mass, and maximal strength were pooled using a random-effects model.

RESULTS

Data from nine randomized controlled trials were included, involving 11 treatments and 192 participants. Overall, with respect to the ingestion of contrast supplements, whey protein supplementation, administered alone or as part of a multi-ingredient, in combination with resistance training, was associated with small extra gains in fat-free mass or lean body mass, resulting in an effect size of g = 0.301, 95% confidence interval (CI) 0.032-0.571. Subgroup analyses showed less clear positive trends resulting in small to moderate effect size g = 0.217 (95% CI -0.113 to 0.547) and g = 0.468 (95% CI 0.003-0.934) in favor of whey and multi-ingredient, respectively. Additionally, a positive overall extra effect was also observed to maximize lower (g = 0.316, 95% CI 0.045-0.588) and upper body maximal strength (g = 0.458, 95% CI 0.161-0.755). Subgroup analyses showed smaller superiority to maximize strength gains with respect to the contrast groups for lower body (whey protein: g = 0.343, 95% CI -0.016 to 0.702, multi-ingredient: g = 0.281, 95% CI -0.135 to 0.697) while in the upper body, multi-ingredient (g = 0.612, 95% CI 0.157-1.068) seemed to produce more clear effects than whey protein alone (g = 0.343, 95% CI -0.048 to 0.735).

LIMITATIONS

Studies involving interventions of more than 6 weeks on resistance-training individuals are scarce and account for a small number of participants. Furthermore, no studies with an intervention longer than 12 weeks have been found. The variation regarding the supplementation protocol, namely the different doses criteria or timing of ingestion also add some concerns to the studies comparison.

CONCLUSIONS

Whey protein alone or as a part of a multi-ingredient appears to maximize lean body mass or fat-free mass gain, as well as upper and lower body strength improvement with respect to the ingestion of an iso-energetic equivalent carbohydrate or non-whey protein supplement in resistance-training individuals. This enhancement effect seems to be more evident when whey proteins are consumed within a multi-ingredient containing creatine.

Four Weeks of Supplementation With Isolated Soy Protein Attenuates Exercise-Induced Muscle Damage and Enhances Muscle Recovery in Well Trained Athletes: A Randomized Trial

BACKGROUND

The effects of consumption of isolated soy protein (ISP) for a chronic period (4 weeks) on exercise induced muscle damage (EIMD) in athletic population have never been explored.

OBJECTIVES

To examine the effects of ISP on muscle damage indices elicited via a bout of damaging exercise.

PATIENTS AND METHODS

Forty males (20 boxers, 20 cyclists) aged 18 - 28 years were randomly assigned to two groups (ISP and Placebo) (n = 20). All participants who engaged themselves in specific, regular training of 30 hours a week during the competitive season were included in the study. Participants consumed the supplement and the placebo for 4 weeks. The damaging exercise consisted of 100 consecutive drop-jumps. Pre and post supplementation readings of the criterion variables, highly sensitive C reactive protein (hs-cRP), creatine Kinase (CK), myeloperoxidase (MPO), isometric muscle strength, maximum aerobic capacity (VO2 max), heart rate (HR) and muscle soreness were obtained at baseline (Day 1), at 24 hours (Day 2) and at 48 hours (Day 3) following EIMD.

RESULTS

Differences were observed in pre and post supplementation values (P < 0.05) indicating the effectiveness of soy protein in attenuating muscle damage and enhancing muscle recovery.

CONCLUSIONS

Our findings suggest that soy protein; a vegetable based supplement is effective, in ameliorating the negative effects of EIMD in trained athletic population.

Protein Supplementation Has Minimal Effects on Muscle Adaptations during Resistance Exercise Training in Young Men: A Double-Blind Randomized Clinical Trial

BACKGROUND

To our knowledge the efficacy of soy-dairy protein blend (PB) supplementation with resistance exercise training (RET) has not been evaluated in a longitudinal study.

OBJECTIVE

Our aim was to determine the effect of PB supplementation during RET on muscle adaptation.

METHODS

In this double-blind randomized clinical trial, healthy young men [18-30 y; BMI (in kg/m(2)): 25 ± 0.5] participated in supervised whole-body RET at 60-80% 1-repetition maximum (1-RM) for 3 d/wk for 12 wk with random assignment to daily receive 22 g PB (n = 23), whey protein (WP) isolate (n = 22), or an isocaloric maltodextrin (carbohydrate) placebo [(MDP) n = 23]. Serum testosterone, muscle strength, thigh muscle thickness (MT), myofiber cross-sectional area (mCSA), and lean body mass (LBM) were assessed before and after 6 and 12 wk of RET.

RESULTS

All treatments increased LBM (P < 0.001). ANCOVA did not identify an overall treatment effect at 12 wk (P = 0.11). There tended to be a greater change in LBM from baseline to 12 wk in the PB group than in the MDP group (0.92 kg; 95% CI: -0.12, 1.95 kg; P = 0.09); however, changes in the WP and MDP groups did not differ. Pooling data from combined PB and WP treatments showed a trend for greater change in LBM from baseline to 12 wk compared with MDP treatment (0.69 kg; 95% CI: -0.08, 1.46 kg; P = 0.08). Muscle strength, mCSA, and MT increased (P < 0.05) similarly for all treatments and were not different (P > 0.10) between treatments. Testosterone was not altered.

CONCLUSIONS

PB supplementation during 3 mo of RET tended to slightly enhance gains in whole-body and arm LBM, but not leg muscle mass, compared with RET without protein supplementation. Although protein supplementation minimally enhanced gains in LBM of healthy young men, there was no enhancement of gains in strength. This trial was registered at clinicaltrials.gov as NCT01749189.

Evidence Supports the Use of Soy Protein to Promote Cardiometabolic Health and Muscle Development

Consumption of adequate amounts of dietary protein can help individuals maintain a healthy body composition, especially when combined with resistance exercise and during weight loss. It is well established that dietary protein intake supports muscle development and helps reduce loss of lean body mass during weight loss. Numerous studies have demonstrated the efficacy of soy protein intake for promoting fat loss while preserving muscle mass and supporting lean body mass gains. In fact, soy protein and animal-based proteins both support weight loss and weight maintenance equally as part of an energy-restricted diet; however, soy protein offers additional cardiometabolic advantages. Key teaching points: Soy protein is a high-quality, plant-based protein that can be consumed throughout the life span. More human clinical studies have been conducted to assess the cholesterol-lowering effects of soy protein than any other cholesterol-lowering food ingredient. Ingestion of proteins with unique and complementary characteristics like soy, whey, and casein helps resistance-trained individuals achieve significant muscle growth. Recent research supports the efficacy of consuming a combination of soy, whey, and casein after resistance exercise to extend the time period that muscle building occurs.

Role of Ingested Amino Acids and Protein in the Promotion of Resistance Exercise-Induced Muscle Protein Anabolism

The goal of this critical review is to comprehensively assess the evidence for the molecular, physiologic, and phenotypic skeletal muscle responses to resistance exercise (RE) combined with the nutritional intervention of protein and/or amino acid (AA) ingestion in young adults. We gathered the literature regarding the translational response in human skeletal muscle to acute exposure to RE and protein/AA supplements and the literature describing the phenotypic skeletal muscle adaptation to RE and nutritional interventions. Supplementation of protein/AAs with RE exhibited clear protein dose-dependent effects on translational regulation (protein synthesis) through mammalian target of rapamycin complex 1 (mTORC1) signaling, which was most apparent through increases in p70 ribosomal protein S6 kinase 1 (S6K1) phosphorylation, compared with postexercise recovery in the fasted or carbohydrate-fed state. These acute findings were critically tested via long-term exposure to RE training (RET) and protein/AA supplementation, and it was determined that a diminishing protein/AA supplement effect occurs over a prolonged exposure stimulus after exercise training. Furthermore, we found that protein/AA supplements, combined with RET, produced a positive, albeit minor, effect on the promotion of lean mass growth (when assessed in >20 participants/treatment); a negligible effect on muscle mass; and a negligible to no additional effect on strength. A potential concern we discovered was that the majority of the exercise training studies were underpowered in their ability to discern effects of protein/AA supplementation. Regardless, even when using optimal methodology and large sample sizes, it is clear that the effect size for protein/AA supplementation is low and likely limited to a subset of individuals because the individual variability is high. With regard to nutritional intakes, total protein intake per day, rather than protein timing or quality, appears to be more of a factor on this effect during long-term exercise interventions. There were no differences in strength or mass/muscle mass on RET outcomes between protein types when a leucine threshold (>2 g/dose) was reached. Future research with larger sample sizes and more homogeneity in design is necessary to understand the underlying adaptations and to better evaluate the individual variability in the muscle-adaptive response to protein/AA supplementation during RET.

Eight weeks of pre- and postexercise whey protein supplementation increases lean body mass and improves performance in Division III collegiate female basketball players

We examined if 8 weeks of whey protein (WP) supplementation improved body composition and performance measures in NCAA Division III female basketball players. Subjects were assigned to consume 24 g WP (n = 8; age, 20 ± 2 years; height, 170 ± 6 cm; weight, 66.0 ± 3.1 kg) or 24 g of maltodextrin (MD) (n = 6; age, 21 ± 3 years; height, 169 ± 6 cm; weight, 68.2 ± 7.6 kg) immediately prior to and following training (4 days/week anaerobic and resistance training) for 8 weeks. Prior to (T1) and 8 weeks following supplementation (T2), subjects underwent dual X-ray absorptiometry body composition assessment as well as performance tests. The WP group gained lean mass from T1 to T2 (+1.4 kg, p = 0.003) whereas the MD group trended to gain lean mass (+0.4 kg, p = 0.095). The WP group also lost fat mass from T1 to T2 (-1.0 kg, p = 0.003) whereas the MD group did not (-0.5 kg, p = 0.41). The WP group presented greater gains in 1-repetition maximum (1RM) bench press (+4.9 kg) compared with the MD group (+2.3 kg) (p < 0.05). Moreover, the WP group improved agility from T1 to T2 (p = 0.001) whereas the MD group did not (p = 0.38). Both groups equally increased leg press 1RM, vertical jump, and broad jump performances. This study demonstrates that 8 weeks of WP supplementation improves body composition and select performance variables in previously trained female athletes.

Bioactive properties of milk proteins in humans: A review

Many studies have demonstrated that milk protein consumption has benefits in terms of promoting human health. This review assesses the intervention studies which have evaluated potential health enhancing effects in humans following the ingestion of milk proteins. The impact of milk protein ingestion has been studied to asses their satiating, hypotensive, antimicrobial, anti-inflammatory, anticancer, antioxidant and insulinotropic properties as well as their impact on morphological modifications (e.g., muscle and fat mass) in humans. Consistent health promoting effects appear to have been observed in certain instances (i.e., muscle protein synthesis, insulinotropic and hypotensive activity). However, controversial outcomes have also been reported (i.e., antimicrobial, anti-inflammatory, anticancer and antioxidant properties). Several factors including interindividual differences, the timing of protein ingestion as well as the potency of the active components may explain these differences. In addition, processing conditions have been reported, in certain instances, to affect milk protein structure and therefore modify their bioactive potential. It is thought that the health promoting properties of milk proteins are linked to the release of bioactive peptides (BAPs) during gastrointestinal digestion. There is a need for further research to develop a more in-depth understanding on the possible mechanisms involved in the observed physiological effects. In addition, more carefully controlled and appropriately powered human intervention studies are required to demonstrate the health enhancing properties of milk proteins in humans.

The Skeletal Muscle Anabolic Response to Plant- versus Animal-Based Protein Consumption

Clinical and consumer market interest is increasingly directed toward the use of plant-based proteins as dietary components aimed at preserving or increasing skeletal muscle mass. However, recent evidence suggests that the ingestion of the plant-based proteins in soy and wheat results in a lower muscle protein synthetic response when compared with several animal-based proteins. The possible lower anabolic properties of plant-based protein sources may be attributed to the lower digestibility of plant-based sources, in addition to greater splanchnic extraction and subsequent urea synthesis of plant protein-derived amino acids compared with animal-based proteins. The latter may be related to the relative lack of specific essential amino acids in plant- as opposed to animal-based proteins. Furthermore, most plant proteins have a relatively low leucine content, which may further reduce their anabolic properties when compared with animal proteins. However, few studies have actually assessed the postprandial muscle protein synthetic response to the ingestion of plant proteins, with soy and wheat protein being the primary sources studied. Despite the proposed lower anabolic properties of plant vs. animal proteins, various strategies may be applied to augment the anabolic properties of plant proteins. These may include the following: 1) fortification of plant-based protein sources with the amino acids methionine, lysine, and/or leucine; 2) selective breeding of plant sources to improve amino acid profiles; 3) consumption of greater amounts of plant-based protein sources; or 4) ingesting multiple protein sources to provide a more balanced amino acid profile. However, the efficacy of such dietary strategies on postprandial muscle protein synthesis remains to be studied. Future research comparing the anabolic properties of a variety of plant-based proteins should define the preferred protein sources to be used in nutritional interventions to support skeletal muscle mass gain or maintenance in both healthy and clinical populations.

Bovine milk-derived α-lactalbumin inhibits colon inflammation and carcinogenesis in azoxymethane and dextran sodium sulfate-treated mice

Cyclooxygenase-2 is expressed early in colon carcinogenesis and plays crucial role in the progress of the disease. Recently, we found that α-lactalbumin had anti-inflammatory activity by inhibiting cyclooxygenase-2. In experiment 1, we investigated the effects of α-lactalbumin on the colon carcinogenesis initiated with azoxymethane (AOM) followed by promotion with dextran sodium sulfate (DSS) in mice. Dietary treatment with α-lactalbumin decreased fecal occult blood score at 3 days after DSS intake. α-Lactalbumin also decreased the colon tumor at week 9. In experiment 2, AOM-treated mice were sacrificed at 7 days after DSS intake. The plasma and colon prostaglandin E2 (PGE2) levels in AOM/DSS-treated mice were higher than those in the DSS-treated mice without initiation by AOM. α-Lactalbumin decreased PGE2 in both plasma and colon. These results suggest that α-lactalbumin effectively inhibited colon carcinogenesis, and the inhibition may be due to the decreased PGE2 by inhibiting cyclooxygenase-2 at cancer promotion stages.

Protein supplementation for military personnel: a review of the mechanisms and performance outcomes

Protein supplement use is common among athletes, active adults, and military personnel. This review provides a summary of the evidence base that either supports or refutes the ergogenic effects associated with different mechanisms that have been proposed to support protein supplementation. It was clear that if carbohydrate delivery was optimal either during or after an acute bout of exercise that additional protein will not increase exercise capacity. Evidence was also weak to substantiate use of protein supplements to slow the increase in brain serotonin and onset of central fatigue. It was also evident that additional research is warranted to test whether the benefits of protein supplements for enhancing recovery of fluid balance after exercise will affect subsequent work in the heat. In contrast, with repeated exercise, use of protein supplementation was associated with reductions in muscle soreness and often a faster recovery of muscle function due to reductions in protein degradation. There was also good supportive evidence for long-term benefits of protein supplementation for gains in muscle mass and strength through accelerated rates of protein synthesis, as long as the training stimulus was of sufficient intensity, frequency, and duration. However, studies have not examined the impact of protein supplements under the combined stress of a military environment that includes repeated bouts of exercise with little opportunity for feeding and recovery, lack of sleep, and exposure to extreme environments. Both additional laboratory and field research is warranted to help provide evidence-based guidance for the choice of protein supplements to enhance soldier performance.

Protein blend ingestion following resistance exercise promotes human muscle protein synthesis

High-quality proteins such as soy, whey, and casein are all capable of promoting muscle protein synthesis postexercise by activating the mammalian target of rapamycin (mTORC1) signaling pathway. We hypothesized that a protein blend of soy and dairy proteins would capitalize on the unique properties of each individual protein and allow for optimal delivery of amino acids to prolong the fractional synthetic rate (FSR) following resistance exercise (RE). In this double-blind, randomized, clinical trial, 19 young adults were studied before and after ingestion of ∼19 g of protein blend (PB) or ∼18 g whey protein (WP) consumed 1 h after high-intensity leg RE. We examined mixed-muscle protein FSR by stable isotopic methods and mTORC1 signaling with western blotting. Muscle biopsies from the vastus lateralis were collected at rest (before RE) and at 3 postexercise time points during an early (0-2 h) and late (2-4 h) postingestion period. WP ingestion resulted in higher and earlier amplitude of blood branched-chain amino acid (BCAA) concentrations. PB ingestion created a lower initial rise in blood BCAA but sustained elevated levels of blood amino acids later into recovery (P < 0.05). Postexercise FSR increased equivalently in both groups during the early period (WP, 0.078 ± 0.009%; PB, 0.088 ± 0.007%); however, FSR remained elevated only in the PB group during the late period (WP, 0.074 ± 0.010%; PB, 0.087 ± 0.003%) (P < 0.05). mTORC1 signaling similarly increased between groups, except for no increase in S6K1 phosphorylation in the WP group at 5 h postexercise (P < 0.05). We conclude that a soy-dairy PB ingested following exercise is capable of prolonging blood aminoacidemia, mTORC1 signaling, and protein synthesis in human skeletal muscle and is an effective postexercise nutritional supplement.

Changes in antioxidant status and cardiovascular risk factors of overweight young men after six weeks supplementation of whey protein isolate and resistance training

The study's purpose was to examine the effects of whey protein supplementation and resistance training on antioxidant status and cardiovascular risk factors in overweight young men. Thirty healthy male subjects (age, 23.4±3.6years; body mass index, 25-30kg/m(2)) were randomly divided into three groups of 10 persons including; Experimental group 1: resistance training+whey supplement (RW); Experimental group 2: resistance training+placebo (RP), and Control group (C). Subjects in intervention groups underwent 3 resistance training sessions per week, each session with 60-70% 1RM, for 6weeks. No significant changes in fibrinogen level, fasting blood glucose, resting systolic and diastolic blood pressures, waist to hip ratio (WHR), and body mass index were observed in any of the groups. Total antioxidant capacity (TAC), cholesterol and HDL varied significantly in the RW group compared with the pre-test. We found significant changes in both RW and RP groups for glutathione, vitamin C, LDL, and triglyceride levels. In addition, in the post-test, TAC, glutathione, and HDL levels were higher in the RW in comparison to C group. Research findings showed that although exercise can lead to antioxidant system improvement and reduce some cardiovascular risk factors among overweight subjects, the combination of resistance training and whey consumption is more effective.

Effects of 28 days of dairy or soy ingestion on skeletal markers of inflammation and proteolysis in post-menopausal women

BACKGROUND

Aging is associated with increased local inflammation and resultant proteolysis in skeletal muscle. In animal models, soy supplementation is a beneficial countermeasure against muscle inflammation and proteolysis; however, the effect on aging humans is not clear.

METHODS

A single-blinded, randomized, controlled trial was conducted on 31 post-menopausal women. Volunteers were randomly assigned to consume three servings of soy (n=16) or dairy (n=15) milk each day for 28 days. The expression of inflammation-responsive (TNF-α, IL-1β, IL-6) and proteolytic (calpain 1, calpain 2, ubiquitin, E2, atrogin-1, muRF-1) genes in skeletal muscle was determined using real-time polymerase chain reaction before and after supplementation, and then after a downhill run performed to elicit muscle damage.

RESULTS

While no group by time interactions were observed, significant main effects for time were observed for IL-1β, IL-6, calpain 2, and atrogin-1 mRNA post exercise. Further analysis revealed that, compared with post-supplementation values, calpain 2 and atrogin-1 mRNA significantly increased at 4 h post exercise (p=0.01 and p<0.01, respectively), whereas IL-1β and IL-6 mRNA significantly decreased at 4 h post exercise (both p<0.01).

CONCLUSIONS

Soy or dairy milk supplementation at the amount ingested for 28 days does not appear to preferentially inhibit the expression of inflammation-responsive and proteolytic genes that were assessed, and does not attenuate the eccentric exercise-induced up-regulation in the proteolytic genes.

Activation of mTOR signalling in young and old human skeletal muscle in response to combined resistance exercise and whey protein ingestion

PURPOSE

To investigate the impact of whey protein ingestion and resistance exercise training on the phosphorylation of mRNA translational signalling proteins in the skeletal muscle of young and old men.

METHODS

Sixteen healthy young (aged 18-25 years) and 15 healthy older men (aged 60-75 years) completed 12 weeks of resistance exercise and were randomly assigned to consume a whey protein (WPI) or placebo drink after each session. Muscle biopsies were collected before and 2 h after an acute exercise bout at the beginning and the end of training.

RESULTS

All subjects significantly increased strength after following strength training. Phosphorylation of mTOR was significantly greater in the WPI groups compared with placebo for both younger and older subjects. Phosphorylation of p70(S6K), eIF4G, and 4EBP1 was greater for older subjects consuming WPI. Phosphorylation of rpS6, eIF4G, and 4EBP1 tended to increase in the younger subjects that had consumed WPI. Post-training, younger subjects demonstrated a similar pattern of mTOR phosphorylation as seen pre-training. In contrast, the initial heightened phosphorylation of mTOR, p70(S6K), rpS6, and eIF4G in older muscle to combined resistance exercise and WPI ingestion became less pronounced after repeated training sessions.

CONCLUSIONS

In the untrained state, resistance exercise coupled with WPI increases the phosphorylation of proteins involved in mRNA translation compared with exercise alone. Post-training, WPI- and exercise-induced protein phosphorylation was reduced in older men, but not in younger men. Thus, strategies to induce hypertrophy should utilize protein and resistance training concurrently. Further investigations should delineate interventions that will maintain sensitivity to anabolic stimuli in older populations.