Acute Microbial Protease Supplementation Increases Net Postprandial Plasma Amino Acid Concentrations After Pea Protein Ingestion in Healthy Adults: A Randomized, Double-Blind, Placebo-Controlled Trial.

BACKGROUND: Digestibility is a primary factor in determining the quality of dietary protein. Microbial protease supplementation may be a strategy for improving protein digestion and subsequent postprandial plasma amino acid availability. OBJECTIVES: To assess the effect of co-ingesting a microbial protease mixture with pea protein on postprandial plasma amino acid concentrations. DESIGN: A mixture of 3 microbial protease preparations (P3) was tested for proteolytic efficacy in an in vitro static simulation of gastrointestinal digestion. Subsequently, in a randomized, double-blind, placebo-controlled crossover trial, 24 healthy adults (27 ± 4 y; 12 females, 12 males) ingested 25 g pea protein isolate (20 g protein, 2.2 g fat) with either P3 or maltodextrin placebo (PLA). Blood samples were collected at baseline and throughout a 0‒5 h postprandial period and both the early (0-2 h) iAUC and total (0-5 h) iAUC were examined. RESULTS: Plasma glucose concentrations decreased in both conditions (P < 0.001), with higher concentrations after P3 ingestion compared with PLA (P < 0.001). Plasma insulin concentrations increased for both conditions (P < 0.001) with no difference between conditions (P = 0.331). Plasma total amino acid (TAA) concentrations increased over time (P < 0.001) with higher concentrations observed for P3 compared with PLA (P = 0.010) during the 0‒5 h period. There was a trend for elevated essential amino acid (EAA) concentrations for P3 compared with PLA (P = 0.099) during the 0‒5 h postprandial period but not for leucine (P = 0.282) or branched-chain amino acids (BCAA, P = 0.410). The early net exposure (0‒2 h iAUC) to amino acids (leucine, BCAA, EAA, and TAA) was higher for P3 compared with PLA (all, P < 0.05). CONCLUSIONS: Microbial protease co-ingestion increases plasma TAA concentrations (0-5 h) and leucine, BCAA, EAA, and TAA availability in the early postprandial period (0‒2 h) compared with ingesting pea protein with placebo in healthy adults.

Evaluation of self-contained breathing apparatus (SCBA) weight on firefighter stamina, comfort, and postural stability.

Firefighters wear personal protective equipment to protect them from the thermal and chemical environment in which they operate. The self-contained breathing apparatus (SCBA) provides isolation of the airway from the hazardous fireground. National standards limit SCBA weight, however, integration of additional features could result in an SCBA exceeding the current limit. The purpose of this study was to examine the effects of increased SCBA weight on firefighters' physiological responses, work output, dynamic stability, and comfort. Completion of simulated firefighting activities induced a strong physiological response. Peak oxygen consumption was higher with the lightest SCBA than the heaviest SCBA. Few other physiological differences were noted as SCBA weight increased. Importantly, increased SCBA weight resulted in significantly more negative perceptions by the firefighters and a trend towards significance for the duration of work time prior to reaching volitional fatigue. These results should be considered when assessing changes to existing SCBA weight limits.

Increased SCBA weight above existing national standards resulted in negative perceptions by the firefighters, but not significant physiological changes after two simulated bouts of firefighting activity. SCBA weight had a nearly significant impact on the time firefighters worked before reaching volitional fatigue, with heavier SCBA trending towards decreased working time.

Postabsorptive muscle protein synthesis is higher in outpatients as compared to inpatients.

Several factors affect muscle protein synthesis (MPS) in the postabsorptive state. Extreme physical inactivity (e.g., bedrest) may reduce basal MPS, whereas walking may augment basal MPS. We hypothesized that outpatients would have a higher postabsorptive MPS than inpatients. To test this hypothesis, we conducted a retrospective analysis. We compared 152 outpatient participants who arrived at the research site the morning of the MPS assessment with 350 Inpatient participants who had an overnight stay in the hospital unit before the MPS assessment the following morning. We used stable isotopic methods and collected vastus lateralis biopsies ∼2 to 3 h apart to assess mixed MPS. MPS was ∼12% higher (P < 0.05) for outpatients than inpatients. Within a subset of participants, we discovered that after instruction to limit activity, outpatients (n = 13) took 800 to 900 steps in the morning to arrive at the unit, seven times more steps than inpatients (n = 12). We concluded that an overnight stay in the hospital as an inpatient is characterized by reduced morning activity and causes a slight but significant reduction in MPS compared with participants studied as outpatients. Researchers should be aware of physical activity status when designing and interpreting MPS results.NEW & NOTEWORTHY The postabsorptive muscle protein synthesis rate is lower in the morning after an overnight inpatient hospital stay compared with an outpatient visit. Although only a minimal amount of steps was conducted by outpatients (∼900), this was enough to increase postabsorptive muscle protein synthesis rate.

Dietary fiber intake and fecal short-chain fatty acid concentrations are associated with lower plasma lipopolysaccharide-binding protein and inflammation.

Consuming adequate dietary fiber is a promising strategy for reducing systemic inflammation. The objective was to evaluate relationships between dietary fiber intake, markers of metabolic endotoxemia, and systemic inflammation in adults. This was a cross-sectional study of 129 healthy participants (age 33.6 ± 6.1 yr, BMI 30.5 ± 6.9 kg/m2). Dietary fiber intake was assessed by food frequency questionnaire. Adiposity was measured using dual-energy X-ray absorptiometry (DXA). Fecal short-chain fatty acids (SCFA) were quantified using gas chromatography-mass spectrometry. Fecal microbiota sequence data (V4 region, 16S rRNA gene) were analyzed using DADA2 and QIIME2. Inflammatory cytokines were assessed with enzyme-linked immunosorbent assays; flow cytometry was conducted for monocyte surface marker quantification. Bivariate correlations and generalized step-wise linear modeling were used for statistical analyses. Plasma C-reactive protein (CRP) and interleukin (IL)-6 concentrations were positively related to whole body (CRP r = 0.45, P = <0.0001; IL-6 r = 0.34, P = 0.0002) and visceral adiposity (CRP r = 0.33, P = 0.0003; IL-6 r = 0.38, P = 0.0002). Plasma lipopolysaccharide-binding protein (LBP) concentrations were inversely related to dietary fiber intake (r = -0.22, P = 0.03) and fecal SCFA (acetate r = -0.25, P = 0.01; propionate r = -0.28, P = 0.003; butyrate r = -0.23, P = 0.02). Whole body adiposity, dietary fiber, and fecal SCFA were the most predictive of plasma LBS-BP concentrations. Novel findings included associations between dietary fiber intake, the gastrointestinal microbiota, and systemic inflammation.NEW & NOTEWORTHY Dietary fiber intake may reduce the inflammation associated with obesity and metabolic disease. Our cross-sectional analysis revealed that dietary fiber intake and fecal short-chain fatty acids are inversely associated with lipopolysaccharide-binding protein, a marker of systemic inflammation. In addition, plasma interleukin-6 and C-reactive protein were positively related to markers of adiposity.

MIND Dietary Pattern Adherence Is Selectively Associated with Cognitive Processing Speed in Middle-Aged Adults.

BACKGROUND: Most previous work has focused on a single-nutrient, bottom-up approach when examining the influence of diet on neurocognition. Thus, the impact of dietary patterns on cognitive health is underinvestigated. OBJECTIVES: We aimed to investigate the relation between different diet indices [i.e., Mediterranean, Dietary Approaches to Stop Hypertension (DASH), Healthy Eating Index-2015 (HEI-2015), and Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND)] and attentional inhibition and neuroelectric function. METHODS: We undertook a cross-sectional analysis of adults aged 34.1 ± 6.0 y (n = 207, 116 females) with a BMI of 18.5 to >40 kg/m2 who completed the Dietary History Questionnaire II (DHQII) FFQ (Past Month and Year with Serving Sizes) to assess adherence to different diet quality indices. Attentional inhibition was assessed using a modified Eriksen flanker task during which event-related potentials (ERPs) were recorded. The amplitude and latency of the P3/P300 ERP were used to index attentional resource allocation and information processing speed, respectively. RESULTS: P3 peak latency was inversely associated with greater adherence to the MIND dietary pattern during incongruent flanker trials (∆R2 = 0.02, ß = -0.14, P = 0.043) but not during congruent trials. Adherence to the Mediterranean, DASH, and HEI-2015 patterns was not associated with P3 latency (P > 0.05). No associations were observed between the diet indices and attentional inhibition at the behavioral level (i.e., accuracy or reaction time) or P3 amplitude (all P values >0.05). CONCLUSIONS: Greater adherence to the MIND diet was selectively associated with faster information processing speed in middle-aged adults with healthy to obese BMI. Further, the influence of the MIND diet for faster information processing speed might be particularly beneficial when cognitive control demands are increased. Future intervention trials testing the effects of consuming a MIND diet on cognitive function are warranted to help inform dietary recommendations for healthy cognitive aging.

Underpinning the Food Matrix Regulation of Postexercise Myofibrillar Protein Synthesis by Comparing Salmon Ingestion With the Sum of Its Isolated Nutrients in Healthy Young Adults.

BACKGROUND: Protein is most commonly consumed as whole foods as opposed to single nutrients. However, the food matrix regulation of the postprandial muscle protein synthetic response has received little attention. OBJECTIVES: The purpose of this study was to assess the effects of eating salmon (SAL) and of ingesting the same nutrients as an isolated mixture of crystalline amino acids and fish oil (ISO) on the stimulation of postexercise myofibrillar protein synthesis (MPS) and whole-body leucine oxidation rates in healthy young adults. METHODS: Ten recreationally active adults (24 ± 4 y; 5 men, 5 women) performed an acute bout of resistance exercise, followed by the ingestion of SAL or ISO in a crossover fashion. Blood, breath, and muscle biopsies were collected at rest and after exercise during primed continuous infusions of L-[ring-2H5]phenylalanine and L-[1-13C]leucine. All data are presented as means ± SD and/or mean differences (95% CIs). RESULTS: Postprandial essential amino acid (EAA) concentrations peaked earlier (P = 0.024) in the ISO group than those in the SAL group. Postprandial leucine oxidation rates increased over time (P < 0.001) and peaked earlier in the ISO group (1.239 ± 0.321 nmol/kg/min; 63 ± 25 min) than those in the SAL group (1.230 ± 0.561 nmol/kg/min; 105 ± 20 min; P = 0.003). MPS rates for SAL (0.056 ± 0.022 %/h; P = 0.001) and ISO (0.046 ± 0.025 %/h; P = 0.025) were greater than the basal rates (0.020 ± 0.011 %/h) during the 0- to 5-h recovery period, with no differences between conditions (P = 0.308). CONCLUSION: We showed that the postexercise ingestion of SAL or ISO stimulate postexercise MPS rates with no differences between the conditions. Thus, our results indicate that ingesting protein from SAL as a whole-food matrix is similarly anabolic to ISO in healthy young adults. This trial was registered at www. CLINICALTRIALS: gov as NCT03870165.

Leucine ingestion promotes mTOR translocation to the periphery and enhances total and peripheral RPS6 phosphorylation in human skeletal muscle.

The activation of the mechanistic target of rapamycin complex 1 (mTORC1), a master regulator of protein synthesis, by anabolic stimuli (such as muscle contraction or essential amino acids) involves its translocation to the cell periphery. Leucine is generally considered the most anabolic of amino acids for its ability to independently modulate muscle protein synthesis. However, it is currently unknown if free leucine impacts region-specific mTORC1-mediated phosphorylation events and protein-protein interactions. In this clinical trial (NCT03952884; registered May 16, 2019), we used immunofluorescence methods to investigate the role of dietary leucine on the postprandial regulation of mTORC1 and ribosomal protein S6 (RPS6), an important downstream readout of mTORC1 activity. Eight young, healthy, recreationally active males (n = 8; 23 ± 3 yrs) ingested 2 g of leucine with vastus lateralis biopsies collected at baseline, 30, 60, and 180 min postprandial. Leucine promoted mTOR translocation to the periphery (~ 18-29%; p ≤ 0.012) and enhanced mTOR localization with the lysosome (~ 16%; both p = 0.049) at 30 and 60 min post-feeding. p-RPS6Ser240/244 staining intensity, a readout of mTORC1 activity, was significantly elevated at all postprandial timepoints in both the total fiber (~ 14-30%; p ≤ 0.032) and peripheral regions (~ 16-33%; p ≤ 0.014). Additionally, total and peripheral p-RPS6Ser240/244 staining intensity at 60 min was positively correlated (r = 0.74, p = 0.036; r = 0.80, p = 0.016, respectively) with rates of myofibrillar protein synthesis over 180 min. The ability of leucine to activate mTORC1 in peripheral regions favors an enhanced rate of MPS, as this is the intracellular space thought to be replete with the cellular machinery that facilitates this anabolic process.

Advanced Glycation End Products and Inflammatory Cytokine Profiles in Maintenance Hemodialysis Patients After the Ingestion of a Protein-Dense Meal.

OBJECTIVE: The goal of this investigation was to evaluate circulating and skeletal muscle inflammatory biomarkers between maintenance hemodialysis (MHD) and demographic-matched control subjects (CON) before and after ingestion of a protein-rich meal. DESIGN AND METHODS: CON (n = 8; 50 ± 2 years; 31 ± 1 kg/m2) and MHD patients (n = 8; 56 ± 5 years; 32 ± 2 kg/m2) underwent a basal blood draw and muscle biopsy and serial blood draws after the ingestion of a mixed meal on a nondialysis day. Plasma advanced glycation end products (AGEs) and markers of oxidation were assessed via liquid chromatography-tandem mass spectrometry before and after the meal (+240 min). Circulating inflammatory cytokines and soluble receptors for AGE (sRAGE) isoforms (endogenous secretory RAGEs and cleaved RAGEs) were determined before and after the meal (+240 min). Basal muscle was probed for inflammatory cytokines and protein expression of related signaling components (RAGE, Toll-like receptor 4, oligosaccharyltransferase subunit 48, TIR-domain-containing adapter-inducing interferon-ß, total IκBα, and pIκBα). RESULTS: Basal circulating AGEs were 7- to 343-fold higher (P < .001) in MHD than those in CON, but only MG-H1 increased in CON after the meal (P < .001). There was a group effect (MHD > CON) for total sRAGEs (P = .02) and endogenous secretory RAGEs (P < .001) and a trend for cleaved RAGEs (P=.09), with no meal effect. In addition, there was a group effect (MHD < CON; P < .05) for circulating fractalkine, interleukin (IL)10, IL17A, and IL1ß and a trend (P < .10) for IL6 and macrophage inflammatory protein 1 alpha, whereas tumor necrosis factor alpha was higher in MHD (P < .001). In muscle, Toll-like receptor 4 (P = .03), TIR-domain-containing adapter-inducing interferon-ß (P = .002), and oligosaccharyltransferase subunit 48 (P = .02) expression was lower in MHD than that in CON, whereas IL6 was higher (P = .01) and IL8 (P = .08) tended to be higher in MHD. CONCLUSION: Overall, MHD exhibited an exaggerated, circulating, and skeletal muscle inflammatory biomarker environment, and the meal did not appreciably affect the inflammatory status.

The role of L-type amino acid transporter 1 (Slc7a5) during in vitro myogenesis.

Satellite cells are required for muscle regeneration, remodeling, and repair through their activation, proliferation, and differentiation; however, how dietary factors regulate this process remains poorly understood. The L-type amino acid transporter 1 (LAT1) transports amino acids, such as leucine, into mature myofibers, which then stimulate protein synthesis and anabolic signaling. However, whether LAT1 is expressed on myoblasts and is involved in regulating myogenesis is unknown. The aim of this study was to characterize the expressional and functional relevance of LAT1 during different stages of myogenesis and in response to growth and atrophic conditions in vitro. We determined that LAT1 is expressed by C2C12 and human primary myoblasts, and its gene expression is lower during differentiation (P < 0.05). Pharmacological inhibition and genetic knockdown of LAT1 impaired myoblast viability, differentiation, and fusion (all P < 0.05). LAT1 protein content in C2C12 myoblasts was not significantly altered in response to different leucine concentrations in cell culture media or in two in vitro atrophy models. However, LAT1 content was decreased in myotubes under atrophic conditions in vitro (P < 0.05). These findings indicate that LAT1 is stable throughout myogenesis and in response to several in vitro conditions that induce muscle remodeling. Further, amino acid transport through LAT1 is required for normal myogenesis in vitro.

Raw Eggs To Support Postexercise Recovery in Healthy Young Men: Did Rocky Get It Right or Wrong?

BACKGROUND: Egg protein is ingested during recovery from exercise to facilitate the postexercise increase in muscle protein synthesis rates and, as such, to support the skeletal muscle adaptive response to exercise training. The impact of cooking egg protein on postexercise muscle protein synthesis is unknown. OBJECTIVES: We sought to compare the impact of ingesting unboiled (raw) compared with boiled eggs during postexercise recovery on postprandial myofibrillar protein synthesis rates. METHODS: In a parallel design, 45 healthy, resistance-trained young men (age: 24 y; 95% CI: 23, 25 y) were randomly assigned to ingest 5 raw eggs (∼30 g protein), 5 boiled eggs (∼30 g protein), or a control breakfast (∼5 g protein) during recovery from a single session of whole-body resistance-type exercise. Primed continuous l-[ring-13C6]-phenylalanine infusions were applied, with frequent blood sampling. Muscle biopsies were collected immediately after cessation of resistance exercise and at 2 and 5 h into the postexercise recovery period. Primary (myofibrillar protein synthesis rates) and secondary (plasma amino acid concentrations) outcomes were analyzed using repeated-measures (time × group) ANOVA. RESULTS: Ingestion of eggs significantly increased plasma essential amino acid (EAA) concentrations, with 20% higher peak concentrations following ingestion of boiled compared with raw eggs (time × group: P < 0.001). Myofibrillar protein synthesis rates were significantly increased during the postexercise period when compared with basal, postabsorptive values in all groups (2-4-fold increase: P < 0.001). Postprandial myofibrillar protein synthesis rates were 20% higher after ingesting raw eggs [0.067%/h; 95% CI: 0.056, 0.077%/h; effect size (Cohen d): 0.63], and 18% higher after ingesting boiled eggs (0.065%/h; 95% CI: 0.058, 0.073%/h; effect size: 0.69) when compared with the control breakfast (0.056%/h; 95% CI: 0.048, 0.063%/h), with no significant differences between groups (time × group: P = 0.077). CONCLUSIONS: The ingestion of raw, as opposed to boiled, eggs attenuates the postprandial rise in circulating EAA concentrations. However, postexercise muscle protein synthesis rates do not differ after ingestion of 5 raw compared with 5 boiled eggs in healthy young men. This trial was registered at the Nederlands Trial Register as NL6506 (www.trialregister.nl).

Dietary lutein plus zeaxanthin and choline intake is interactively associated with cognitive flexibility in middle-adulthood in adults with overweight and obesity.

BACKGROUND: The xanthophyll carotenoids lutein+zeaxanthin and the dietary component choline have been linked to benefits in cognition. However, knowledge on the interactive influence of these dietary components on cognitive function is sparse. DESIGN: 80 middle-aged adults with overweight and obesity (Body Mass Index: (BMI) ≥25.0 kg/m²), completed 7-day diet records, venous blood draws, heterochromatic flicker photometry, assessment of intelligence quotient (IQ), and a cognitive flexibility task while undergoing electroencephalographic recording for event-related potential (ERP) extraction. Multiplicative interaction terms and hierarchical linear regressions, controlling for age, BMI, sex, annual household income, and IQ were utilized to assess independent and interactive contributions of dietary and biomarker data on Switch task outcomes. RESULTS: Higher intake of lutein+zeaxanthin and choline was associated interactively, but not independently, with faster reaction time (RT), after controlling for pertinent covariates. Dietary intake of lutein+zeaxanthin and choline was associated with serum lutein concentrations, but not with plasma choline metabolites nor macular pigmentation. Plasma phosphatidylcholine (PC) concentrations were associated with higher accuracy in Switch trials, while no other biomarkers were associated with cognitive outcomes. Dietary intake and biomarker data were not related to the N2 nor P3 ERP component. CONCLUSIONS: Among a sample of adults with overweight and obesity, greater intake of choline and lutein+zeaxanthin was associated with faster performance on a cognitive flexibility task. Future work examining methods of increasing consumption of both of these dietary components as a possible means of improving or maintaining cognitive flexibility among adults with overweight and obesity is therefore warranted.

Creatine Monohydrate Supplementation, but not Creatyl-L-Leucine, Increased Muscle Creatine Content in Healthy Young Adults: A Double-Blind Randomized Controlled Trial.

Creatine (Cr) supplementation is a well-established strategy to enhance gains in strength, lean body mass, and power from a period of resistance training. However, the effectiveness of creatyl-L-leucine (CLL), a purported Cr amide, is unknown. Therefore, the purpose of this study was to assess the effects of CLL on muscle Cr content. Twenty-nine healthy men (n = 17) and women (n = 12) consumed 5 g/day of either Cr monohydrate (n = 8; 28.5 ± 7.3 years, 172.1 ± 11.0 cm, 76.6 ± 10.7 kg), CLL (n = 11; 29.2 ± 9.3 years, 170.3 ± 10.5 cm, 71.9 ± 14.5 kg), or placebo (n = 10; 30.3 ± 6.9 years, 167.8 ± 9.9 cm, 69.9 ± 11.1 kg) for 14 days in a randomized, double-blind design. Participants completed three bouts of supervised resistance exercise per week. Muscle biopsies were collected before and after the intervention for quantification of muscle Cr. Cr monohydrate supplementation which significantly increased muscle Cr content with 14 days of supplementation. No changes in muscle Cr were observed for the placebo or CLL groups. Cr monohydrate supplementation is an effective strategy to augment muscle Cr content while CLL is not.

Early resistance training-mediated stimulation of daily muscle protein synthetic responses to higher habitual protein intake in middle-aged adults.

KEY POINTS: The ingestion of protein potentiates the stimulation of myofibrillar protein synthesis rates after an acute bout of resistance exercise. Protein supplementation (eating above the protein Recommended Dietary Allowance) during resistance training has been shown to maximize lean mass and strength gains in healthy young and older adults. Here, contractile, oxidative, and structural protein synthesis were assessed in skeletal muscle in response to a moderate or higher protein diet during the early adaptive phase of resistance training in middle-aged adults. The stimulation of myofibrillar, mitochondrial or collagen protein synthesis rates during 0-3 weeks of resistance training is not further enhanced by a higher protein diet. These results show that moderate protein diets are sufficient to support the skeletal muscle adaptive response during the early phase of a resistance training programme. ABSTRACT: Protein ingestion augments muscle protein synthesis (MPS) rates acutely after resistance exercise and can offset age-related loss in muscle mass. Skeletal muscle contains a variety of protein pools, such as myofibrillar (contractile), mitochondrial (substrate oxidation), and collagen (structural support) proteins, and the sensitivity to nutrition and exercise seems to be dependent on the major protein fraction studied. However, it is unknown how free-living conditions with high dietary protein density and habitual resistance exercise mediates muscle protein subfraction synthesis. Therefore, we investigated the effect of moderate (MOD: 1.06 ± 0.22 g kg-1  day-1 ) or high (HIGH: 1.55 ± 0.25 g kg-1  day-1 ) protein intake on daily MPS rates within the myofibrillar (MyoPS), mitochondrial (MitoPS) and collagen (CPS) protein fractions in middle-aged men and women (n = 20, 47 ± 1 years, BMI 28 ± 1 kg m-2 ) during the early phase (0-3 weeks) of a dietary counselling-controlled resistance training programme. Participants were loaded with deuterated water, followed by daily maintenance doses throughout the intervention. Muscle biopsies were collected at baseline and after weeks 1, 2 and 3. MyoPS in the HIGH condition remained constant (P = 1.000), but MOD decreased over time (P = 0.023). MitoPS decreased after 0-3 weeks when compared to 0-1 week (P = 0.010) with no effects of protein intake (P = 0.827). A similar decline with no difference between groups (P = 0.323) was also observed for CPS (P = 0.007). Our results demonstrated that additional protein intake above moderate amounts does not potentiate the stimulation of longer-term MPS responses during the early stage of resistance training adaptations in middle-aged adults.

Higher protein intake during resistance training does not potentiate strength, but modulates gut microbiota, in middle-aged adults: a randomized control trial.

Protein intake above the recommended dietary allowance (RDA) and resistance training are known anabolic stimuli to support healthy aging. Specifically, protein supplementation after resistance exercise and nightly are strategies to maximize utilization of protein intake above the RDA in healthy adults. As such, the primary objective was to examine the efficacy of protein supplementation and nutritional counseling resulting in either moderate (MOD: ∼1.0 g·kg-1·day-1) or higher (HIGH: ∼1.6 g·kg-1·day-1) protein intake during resistance training on strength (one-repetition maximum, 1-RM; isokinetic and isometric peak torque) in healthy middle-aged adults. Exploratory analyses include diet-exercise effects on lean body mass (LBM), clinical biomarkers, gut microbiota, and diet composition. In all, 50 middle-aged adults (age: 50 ± 8 yr, BMI: 27.2 ± 4.1 kg/m2) were randomized to either MOD or HIGH protein intake during a 10-wk resistance training program (3 × wk). Participants received dietary counseling and consumed either 15 g (MOD) or 30 g (HIGH) of protein from lean beef in the immediate postexercise period and each evening. Maximal strength (1-RM) for all upper and lower body exercises significantly increased with no effect of protein intake (P < 0.050). There was a main effect of time for LBM (P < 0.005). Cardiovascular, renal, or glycemic biomarkers were not affected by the intervention. Gut microbiota were associated with several health outcomes (P < 0.050). In conclusion, higher protein intake above moderate amounts does not potentiate resistance training adaptations in previously untrained middle-aged adults. This trial was registered at clinicaltrials.gov as NCT03029975.NEW & NOTEWORTHY Our research evaluates the efficacy of higher in comparison with moderate animal-based protein intake on resistance exercise training-induced muscle strength, clinical biomarkers, and gut microbiota in middle-aged adults through a dietary counseling-controlled intervention. Higher protein intake did not potentiate training adaptations, nor did the intervention effect disease biomarkers. Both diet and exercise modified gut microbiota composition. Collectively, moderate amounts of high-quality, animal-based protein is sufficient to promote resistance exercise adaptations at the onset of aging.

The relationships between prolonged sedentary time, physical activity, cognitive control, and P3 in adults with overweight and obesity.

BACKGROUND/OBJECTIVES: To assess the relationships between daily sedentary time (ST), prolonged ST, moderate-to-vigorous physical activity (MVPA), and behavioral and neuroelectric indices of cognitive control in adults with overweight and obesity (OW/OB). SUBJECTS/METHODS: A cross-sectional design was used. Overall, 89 adults (BMI = 31.9 ± 4.9 kg/m2) provided measures of ST, prolonged ST (i.e., ST accumulated in ≥20 min), and MVPA from a hip-worn accelerometer worn over 7 days. Inhibitory control was measured with a modified Eriksen flanker task and cognitive flexibility with task switching. The amplitude and the latency of the P3 component of event-related potentials during each task were used as measures of attentional resource allocation and information processing speed, respectively. RESULTS: After adjusting for ST and MVPA, prolonged ST was related to greater interference (i.e., a larger decrement in accuracy between congruent and incongruent trials of the flanker task) indicative of a specific relationship between prolonged ST and poorer inhibitory control. Before adjusting for ST, MVPA was related to a smaller Global Switch Cost expressed as larger (more positive) amplitude of the P3 difference wave (mixed-task minus single-task condition of the switch task). Adjustment for ST attenuated this association to non-significance. CONCLUSIONS: Our findings suggest that future interventions focused on improving inhibitory control in adults with OW/OB should target restructuring ST in addition to current efforts to increase MVPA.

Avocado Consumption Alters Gastrointestinal Bacteria Abundance and Microbial Metabolite Concentrations among Adults with Overweight or Obesity: A Randomized Controlled Trial.

BACKGROUND: Avocados are rich in dietary fiber and monounsaturated fatty acids (MUFAs), nutrients that have been independently connected to metabolic health benefits and the gastrointestinal microbiota. OBJECTIVES: We aimed to evaluate the impact of avocado consumption on the gastrointestinal microbiota and microbial metabolites, secondary outcomes of the Persea americana for Total Health (PATH) study, and conduct exploratory analyses to assess relations between the fecal microbiota, fecal metabolites, and health markers. METHODS: Adults [n = 163, 25-45 y, BMI (kg/m2) ≥ 25.0] were enrolled in the PATH study, a 12-wk investigator-blinded trial where participants were batch randomized to match the 2 groups by age, sex, visceral adiposity, and fasting glucose concentrations. Participants consumed isocaloric meals with or without avocado (175 g, men; 140 g, women) once daily for 12 wk. The fecal microbiota was assessed with 16S ribosomal RNA gene (V4 region) sequencing and analysis using DADA2 and QIIME2. Fecal fatty acid and bile acid concentrations were quantified using GC and LC-MS. Per-protocol (≥80% meal consumption) and intent-to-treat analyses were conducted using univariate ANOVA and Mann-Whitney U tests. Bivariate correlations were conducted between fecal microbiota, fecal metabolites, and health measures. RESULTS: The avocado treatment increased ɑ diversity and enriched Faecalibacterium, Lachnospira, and Alistipes between 26% and 65% compared with the control group. The avocado group had 18% greater fecal acetate, 70% greater stearic acid, and 98% greater palmitic acid concentrations than the control group, while the concentrations of the bile acids cholic and chenodeoxycholic acid were 91% and 57% lower, respectively. CONCLUSIONS: Daily avocado consumption resulted in lower fecal bile acid concentrations, greater fecal fatty acid and SCFAs, and greater relative abundances of bacteria capable of fiber fermentation, providing evidence that this nutrient-dense food affects digestive physiology, as well as the composition and metabolic functions of the intestinal microbiota. This trial was registered at www.clinicaltrials.gov as NCT02740439.

Avocado Consumption, Abdominal Adiposity, and Oral Glucose Tolerance Among Persons with Overweight and Obesity.

BACKGROUND: Although intake of Hass avocado has been cross-sectionally linked to lower abdominal obesity, knowledge of the effects of avocado consumption on abdominal adiposity and glycemic outcomes remains limited. OBJECTIVE: The effects of avocado consumption on abdominal adiposity, insulin resistance, oral-glucose-tolerance test (OGTT), and estimated ß-cell function were evaluated. METHODS: A total of 105 adults aged 25-45 y (61% female) with BMI ≥25 kg/m2 were randomly assigned to an intervention (N = 53) that received a daily meal with 1 fresh Hass avocado or a control (N = 52) that received an isocaloric meal with similar ingredients without avocado for 12 wk. DXA was used to assess the primary outcomes of abdominal adiposity [visceral adipose tissue (VAT), subcutaneous abdominal adipose tissue (SAAT), and the ratio of VAT to SAAT (VS Ratio)]. Fasted glucose and insulin were used to assess the primary outcomes of insulin resistance (HOMA-IR), and insulin sensitivity (Matsuda index) and ß-cell function (Insulinogenic index) were estimated using an OGTT. Changes between groups were compared using an ANCOVA. Secondary analyses were conducted based on sex. RESULTS: The control group exhibited a greater reduction in SAAT [-54.5 ± 155.8 g (control) compared with 17.4 ± 155.1 g (treatment), P = 0.017] and increase in VS Ratio [0.007 ± 0.047 (control) compared with -0.011 ± 0.044 (treatment), P = 0.024]. Among females, the treatment group exhibited a greater reduction in VAT [1.6 ± 89.8 g (control) compared with -32.9 ± 81.6 g (treatment), P = 0.021] and VS Ratio [0.01 ± 0.05 (control) compared with -0.01 ± 0.03 (treatment), P = 0.001]. Among males, there was no significant difference between groups in changes in abdominal adiposity or glycemic outcomes. CONCLUSIONS: Daily consumption of 1 fresh Hass avocado changed abdominal adiposity distribution among females but did not facilitate improvements in peripheral insulin sensitivity or ß-cell function among adults with overweight and obesity.This study was registered at clinicaltrials.gov as NCT02740439.

Hydration Biomarkers Are Related to the Differential Abundance of Fecal Microbiota and Plasma Lipopolysaccharide-Binding Protein in Adults.

INTRODUCTION: Prevalence of chronic hypohydration remains elevated among adults in the USA; however, the health effects of hypohydration in regards to human gut health have not been explored. METHODS: This study examined the relationship between total water intake, hydration biomarkers (first-morning urine specific gravity [FMUsg], first-morning urine volume [FMUvol], and plasma copeptin), fecal microbiota, and plasma lipopolysaccharide-binding protein (LBP) in adults (25-45 years, 64% female). Fecal microbiota composition was assessed using 16S rRNA gene sequencing (V4 region). Immunoassays quantified plasma copeptin and LBP in fasted venous blood samples. Dietary variables were measured using 7-day food records. Linear discriminant analysis effect size (LEfSe) analyzed differentially abundant microbiota based on median cutoffs for hydration markers. Multiple linear regressions examined the relationship between LBP and copeptin. RESULTS: LEfSe identified 6 common taxa at the genus or species level that were differentially abundant in FMUsg, total water (g/day), or plasma copeptin (µg/mL) groups when split by their median values. Uncultured species in the Bacteroides, Desulfovibrio, Roseburia, Peptococcus, and Akkermansia genera were more abundant in groups that might indicate poorer hydration status. Multivariate linear analyses revealed a positive relationship between plasma copeptin and LBP when controlling confounding variables (F(6,52) = 4.45, p = 0.002, R2 = 0.34). CONCLUSIONS: Taxa common between markers are associated with the intestinal mucus layer, which suggests a potential link between hydration status and intestinal mucus homeostasis. The relationship between LBP and copeptin indicates that copeptin may be sensitive to metabolic endotoxemia and potentially gut barrier function.

Integrin-associated ILK and PINCH1 protein content are reduced in skeletal muscle of maintenance haemodialysis patients.

KEY POINTS: Patients with renal failure undergoing maintenance haemodialysis are associated with insulin resistance and protein metabolism dysfunction. Novel research suggests that disruption to the transmembrane protein linkage between the cytoskeleton and the extracellular matrix in skeletal muscle may contribute to reduced amino acid metabolism and insulin resistance in haemodialysis. ILK, PINCH1 and pFAKTyr397 were significantly decreased in haemodialysis compared to controls, whereas Rac1 and Akt2 showed no different between groups. Rac1 deletion in the Rac1 knockout model did not alter the expression of integrin-associated proteins. Phenylalanine kinetics were reduced in the haemodialysis group at 30 and 60 min post meal ingestion compared to controls; both groups showed similar levels of insulin sensitivity and ß-cell function. Key proteins in the integrin-cytoskeleton linkage are reduced in haemodialysis patients, suggesting for the first time that integrin-associated proteins dysfunction may contribute to reduced phenylalanine flux without affecting insulin resistance in haemodialysis patients. ABSTRACT: Muscle atrophy, insulin resistance and reduced muscle phosphoinositide 3-kinase-Akt signalling are common characteristics of patients undergoing maintenance haemodialysis (MHD). Disruption to the transmembrane protein linkage between the cytoskeleton and the extracellular matrix in skeletal muscle may contribute to reduced amino acid metabolism and insulin resistance in MHD patients. Eight MHD patients (age: 56 ± 5 years: body mass index: 32 ± 2 kg m-2 ) and non-diseased controls (age: 50 ± 2 years: body mass index: 31 ± 1 kg m-2 ) received primed continuous l-[ring-2 H5 ]phenylalanine before consuming a mixed meal. Phenylalanine metabolism was determined using two-compartment modelling. Muscle biopsies were collected prior to the meal and at 300 min postprandially. In a separate experiment, skeletal muscle tissue from muscle-specific Rac1 knockout (Rac1 mKO) was harvested to investigate whether Rac1 depletion disrupted the cytoskeleton-integrin linkage, allowing for cross-model examination of proteins of interest. ILK, PINCH1 and pFAKTyr397 were significantly lower in MHD (P < 0.01). Rac1 and Akt showed no difference between groups for the human trial. Rac1 deletion in the Rac1 mKO model did not alter the expression of integrin-associated proteins. Phenylalanine rates of appearance and disappearance, as well as metabolic clearance rates, were lower in the MHD group at 30 and 60 min post meal ingestion compared to controls (P < 0.05). Both groups showed similar levels of insulin sensitivity and ß-cell function. Key proteins in the integrin-cytoskeleton linkage are reduced in MHD patients, suggesting for the first time that integrin-associated proteins dysfunction may contribute to reduced phenylalanine flux without affecting insulin resistance in haemodialysis patients.

Single Nucleotide Polymorphisms Related to Lipoprotein Metabolism Are Associated with Blood Lipid Changes following Regular Avocado Intake in a Randomized Control Trial among Adults with Overweight and Obesity.

BACKGROUND: Avocados are rich in unsaturated fat and fiber; clinical trials have investigated their effects on metabolic disease. There is high variability in individual changes following avocado consumption, which may be in part due to individual genetic differences. OBJECTIVE: Secondary analyses of the Persea americana for Total Health (PATH) Study were used to examine how single nucleotide polymorphisms (SNPs) impact blood lipid changes following a daily meal containing avocado compared with control. METHODS: Adults (n = 115, 37% male) aged 25-45 y with overweight and obesity were randomly assigned to receive a daily isocaloric meal with (intervention) or without (control) a standardized amount (males: 175 g; females: 140 g) of avocado for 12 wk. Control meals were higher in saturated fat (17% of energy compared with 7%) and lower in fiber (4 g compared with 16 g) than intervention meals. Whole venous blood was taken at baseline and 12 wk to determine total cholesterol (TC), high-density lipoprotein (HDL) cholesterol, and triglyceride (TG) concentrations. Seventeen SNPs in 10 genes related to lipoprotein metabolism were genotyped. Effects of SNP, diet, and SNP-diet interactions were determined using general linear models. RESULTS: No group-by-time effects were detected for changes in TC (P = 0.96), HDL cholesterol (P = 0.28), or TG (P = 0.06) over 12 wk. Three SNP-diet interactions were associated with final TC concentrations: ANGPTL3-rs10889337 (P = 0.01), ANGPTL4-rs2278236 (P = 0.02), and CD36-rs10499859 (P = 0.01). SNPs in GCKR and LPL were associated with TC changes (P = 0.01). The interaction between GCKR-rs1260326 and diet was such that C-homozygotes receiving avocado (n = 23) had final TC concentrations that were significantly lower than the C-homozygotes in the control group (n = 20) (P = 0.02). CONCLUSIONS: Results from these exploratory analyses indicate that avocado consumption may help manage dyslipidemia in adults with overweight and obesity; however, effectiveness may differ by genetic profile. Understanding the role of genetic variation in variability following dietary intervention can potentially inform personalized nutrition recommendations.