From bytes to bites: Advancing the food industry with three-dimensional food printing.

The rapid advancement of three-dimensional (3D) printing (i.e., a type of additive manufacturing) technology has brought about significant advances in various industries, including the food industry. Among its many potential benefits, 3D food printing offers a promising solution to deliver products meeting the unique nutritional needs of diverse populations while also promoting sustainability within the food system. However, this is an emerging field, and there are several aspects to consider when planning for use of 3D food printing for large-scale food production. This comprehensive review explores the importance of food safety when using 3D printing to produce food products, including pathogens of concern, machine hygiene, and cleanability, as well as the role of macronutrients and storage conditions in microbial risks. Furthermore, postprocessing factors such as packaging, transportation, and dispensing of 3D-printed foods are discussed. Finally, this review delves into barriers of implementation of 3D food printers and presents both the limitations and opportunities of 3D food printing technology.

Leucine decreases intramyocellular lipid deposition in an mTORC1-independent manner in palmitate-treated C2C12 myotubes.

Higher intramyocellular lipid (IMCL) deposition in skeletal muscle is commonly observed in patients with obesity, resulting in mitochondrial damage. Palmitic acid, a saturated fatty acid, has been reported to induce obesogenic conditions in C2C12 myotubes. Leucine has been shown to improve obesity-related metabolic signatures; however, evidence for the effect of leucine on IMCL and the underlying mechanisms are still lacking. The objective of this study was to determine the effect of leucine on IMCL deposition and identify the potential mechanisms. Palmitate-treated C2C12 myotubes were used as an in vitro model of obesity. Two doses of leucine were used: 0.5 mM (postprandial physiological plasma concentration) and 1.5 mM (supraphysiological plasma concentration). Rapamycin was used to determine the role of mammalian target of rapamycin complex 1 (mTORC1) in leucine's regulation of lipid deposition in C2C12 myotubes. One-way ANOVA followed by Tukey's post hoc test was used to calculate differences between treatment groups. Our results demonstrate that leucine reduces IMCL deposition in an mTORC1-independent fashion. Furthermore, leucine acts independently of mTORC1 to upregulate gene expression related to fatty acid metabolism and works through both mTORC1-dependent and mTORC1-independent pathways to regulate mitochondrial biogenesis in palmitate-treated C2C12 myotubes. In agreement with increased mitochondrial biogenesis, increased mitochondrial content, circularity, and decreased autophagy are observed in the presence of 1.5 mM leucine. Taken together, the results indicate leucine reduces IMCL potentially through an mTORC1-independent pathway in palmitate-treated C2C12 myotubes.

Educational nutrition messaging at breakfast reduces snack intake and influences snack preferences in adult men and women.

Breakfast skipping is associated with increased risk of weight gain and obesity in young adults, possibly due to increased snacking later in the day. Recent research suggests that providing and animal versus a plant source of protein at breakfast can reduce snack intake later in the day. In addition, providing nutrition information via a nutrition label, front-of-pack information, or via text messaging has been shown to help individuals make healthier food choices. The objective of this study was to determine if educational nutrition messaging and protein source influenced snack intake 2 h following the breakfast meal. Participants (n = 33) were randomly assigned to one of two groups: educational nutrition messaging (EM; n = 16) or no messaging (NM; n = 17) group. The study was conducted using a randomized, cross-over design in which each participant received each of two breakfast beverages, whey protein- (WP) and pea protein (PP)- based. Appetite was assessed at 0, 15, 30, 60, 90, and 120 min after each test breakfast using visual analog scales. Participants were then provided with a selection of healthy and unhealthy snacks for 60 min. There was no effect of protein source on appetite or snack intake. However, participants presented with EM had reduced snack intake over the snacking period compared to NM (P = 0.058) and, of the snacks consumed, the EM group consumed a higher percentage of healthy versus unhealthy snacks compared to NM (P < 0.0001), resulting in lower calorie intake. Taken together these data suggest that protein source, as part of a higher protein breakfast, does not affect appetite response or snack intake, but EM may help play a role in reducing snack intake between meals.

Effects of 28-Day Beta-Alanine Supplementation on Isokinetic Exercise Performance and Body Composition in Female Masters Athletes.

Beta-alanine (BA) supplementation increases exercise performance due to increases in the intramuscular lactate buffer, carnosine. Females are more sensitive to these increases and results are further pronounced in trained individuals. Baseline intramuscular carnosine levels also naturally decrease with age; therefore, trained older females may experience augmented benefits from BA supplementation. However, the ability of BA to increase lower-body isokinetic strength (ISO) in female masters athletes (MA) is unknown. The purpose of this study was to examine the longitudinal effects of BA supplementation on ISO, handgrip strength (HG), and body composition in female MA cyclists. Twenty-two subjects participated in this double-blind randomized study. Subjects were randomized into 2 groups (placebo [PLA] = 8 g dextrose; BA = 800 mg + 8 g dextrose) and supplemented 4 times per day for 28 days. ISO, HG, and body composition were evaluated at baseline and at the same day/time each week over the 28-day intervention. No differences existed between groups at baseline or at the 7, 14, and 21 days time points for any variables (p > 0.05). When evaluating ISO (isokinetic) after 28 days, total work performed during the final third of the assessment (24.0 vs. -16.8% change) in flexion and average peak torque (5.4 vs. 2.9% change) in extension were significantly increased from baseline in BA compared with PLA (p ≤ 0.05). No differences existed for HG or body composition after supplementation. Twenty-eight days of BA supplementation increased peak torque and work completed, indicating BA improves lower-body exercise performance in female MA.

Breakfasts Higher in Protein Increase Postprandial Energy Expenditure, Increase Fat Oxidation, and Reduce Hunger in Overweight Children from 8 to 12 Years of Age.

BACKGROUND: Currently 1 in every 3 children aged 2-19 y is overweight or obese. Breakfast is a key component of a healthy diet and has the potential to affect children's health. OBJECTIVE: The objective of this study was to determine whether consumption of a protein-based breakfast (PRO) increases postprandial energy metabolism and substrate oxidation, reduces hunger, and reduces food intake at lunch compared with a carbohydrate-based breakfast (CHO) in normal weight (NW) vs. overweight/obese (OW) children. METHODS: A randomized, crossover-design study was conducted in NW (n = 16; 33 ± 1 kg) and OW (n = 13; 46 ± 2 kg) children (10 ± 1 y). Participants were served either a PRO [344 kcal, 21% protein (18 g), 52% carbohydrate, and 27% fat] or CHO [327 kcal, 4% protein (3 g), 67% carbohydrate, and 29% fat]. Energy expenditure (EE), substrate oxidation, appetite, and blood glucose were measured over a 4 h period. Four hour postprandial participants were provided with access to a lunch buffet and food intake was recorded. RESULTS: After breakfast, OW children in the PRO group had higher (P < 0.0001) EEs and fat oxidation over the 4 h period than did the NW children in the CHO and PRO groups. There was no difference in postprandial EE or carbohydrate oxidation between the CHO and PRO groups over the 4 h period; however, fat oxidation was 16% higher (P < 0.05) after the PRO than the CHO and postprandial carbohydrate oxidation at 4 h was 32% higher after the PRO than the CHO (P < 0.01), independent of weight group. All participants had decreased feelings of hunger (-14%; P < 0.01) and increased fullness (+32%; P < 0.05) after the PRO than the CHO. Finally, there was no difference in food intake within the NW and OW groups. CONCLUSION: This study indicates that breakfast macronutrient composition affects postprandial responses in both NW and OW children. A PRO increases postprandial EE and fat oxidation, reduces hunger, and increases satiety when compared with a carbohydrate-based breakfast.

Nutrition as the foundation for successful aging: a focus on dietary protein and omega-3 polyunsaturated fatty acids.

Skeletal muscle plays a critical role throughout the aging process. People living with sarcopenia, a progressive and generalized loss of skeletal muscle mass and function, often experience diminished quality of life, which can be attributed to a long period of decline and disability. Therefore, it is important to identify modifiable factors that preserve skeletal muscle and promote successful aging (SA). In this review, SA was defined as (1) low cardiometabolic risk, (2) preservation of physical function, and (3) positive state of wellbeing, with nutrition as an integral component. Several studies identify nutrition, specifically high-quality protein (eg, containing all essential amino acids), and long-chain omega-3 polyunsaturated fatty acids (n-3 PUFAs), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), as positive regulators of SA. Recently, an additive anabolic effect of protein and n-3 PUFAs has been identified in skeletal muscle of older adults. Evidence further suggests that the additive effect of protein and n-3 PUFAs may project beyond skeletal muscle anabolism and promote SA. The key mechanism(s) behind the enhanced effects of intake of protein and n-3 PUFAs needs to be defined. The first objective of this review is to evaluate skeletal muscle as a driver of cardiometabolic health, physical function, and wellbeing to promote SA. The second objective is to examine observational and interventional evidence of protein and n-3 PUFAs on skeletal muscle to promote SA. The final objective is to propose mechanisms by which combined optimal intake of high-quality protein and n-3 PUFAs likely play a key role in SA. Current evidence suggests that increased intake of protein above the Recommended Dietary Allowance and n-3 PUFAs above the Dietary Guidelines for Americans recommendations for late middle-aged and older adults is required to maintain skeletal muscle mass and to promote SA, potentially through the mechanistical target of rapamycin complex 1 (mTORC1).

The design and development of a dashboard for improving sustainable healthy food choices.

Over the last decade, several digital tools have been designed to provide consumers with nutritional and environmental impact information about their food choices post-consumption. Many of these tools lack behavioral change modules, have low user engagement, and ignore inherent environmental nutrition trade-offs to stimulate dietary change. This study presents the design and development of a decision support system to enhance consumer health while meeting sustainability goals from a pre-consumption perspective. The proposed decision support system, Dashboard for Improving Sustainable Healthy (DISH) food choices, employs behavioral features, traffic light labels, and nudges to inform end-users about the nutritional health performance and environmental impact of meals. DISH uses a simple metric that allows end-users to explore the potential minutes of healthy and productive life gained or lost from consuming 100 kcal of a meal. The metric combines the positive or negative nutritional health effects (µ-DALYs) of consuming a meal and environmental damage (endpoint impact expressed in DALYs) on human health. In the DISH application, end-users are rewarded or deducted EnCoins, which represent the number of silver or gold coins lost or gained based on the cost ($) of environmental damage (midpoint impacts) of a meal compared to reference sustainable healthy and unsustainable and unhealthy meal. DISH's gamification module enables end-users to track the potential minutes of healthy and productive life gained/lost and gold or silver rewards or deductions from consuming 100 kcal of a selected meal through cumulative minutes gained or lost and EnCoins. In promoting a sustainable diet culture, the gamification module enables users to create groups and communities where friends and families can track their sustainability performance through meal decisions. The DISH application is currently available online and can be accessed by an end-user through any device. Further pilot studies will focus on testing the technology in partner campus cafeterias.

Nutritional-environmental trade-offs in potato storage and processing for a sustainable healthy diet.

Over the last decade, poor diets and limited access to nutritious foods have been critical drivers of micronutrient deficiency in human health. However, food fortification at an industrialized scale in developed countries has helped eliminate deficiency-related diseases. In developing countries, fortified foods and biofortified materials have been delivered to nutrient-deficient communities. While these strategies have produced significant and acclaimed results, reports from the Food and Agricultural Organization suggest that over a quarter of the world's population suffers from micronutrient deficiency. This implies that there are still declines in micronutrients in food products at different nodes along the food value chain (FVC). Hence, this study sets out to track micronutrient leakages at specific nodes of the FVC using potato household storage, processing, and consumption in the United States as a case study. The experiment was laid out in a full factorial design with three storage conditions (cupboard at (17.5-22.4 °C, 32.7-48% RH), refrigerator at (-1.8 - 0.89 °C, 37.5-66.1% RH) and ideal condition at (7.2-11.1 °C, 85.0-92.4% RH)), two storage times (2 weeks (±3 days) and 5 weeks (±3 days)) and three household processing pathways (boiling in water, baking at 204 °C, and frying in vegetable oil at 149-204 °C). Additionally, we explored the dynamics of optimal household storage and processing pathways by placing a high, low, or equal priority on environmental sustainability or nutrient retention. The results show that storing potatoes for 5 weeks (±3 days) and processing through boiling (in water at 100 °C), baking (at 204 °C), and frying (in vegetable oil at 149-204 °C) are associated with 33.5%, 40.3% and 15.0% greater nutrient loss than a similar processing scenario after 2 weeks (±3 days) of storage. Additionally, storing and processing potatoes after 5 weeks (±3 days) results in approximately 2.2 ± 0.7 times more damage to human health, ecosystem safety, and resource availability than storing and processing potatoes after 2 weeks (±3 days), averaged between the different storage conditions. Storing and processing after 5 weeks (±3 days) results in approximately 53.6 ± 10.3 times more damage to human health, species disappearing per year, and USD loss than freshly purchased and processed potatoes. Perhaps the most significant finding from the study is that storing potatoes in cupboards and boiling (BL-CP pathway) is optimal for achieving a sustainable healthy diet, as it yields the optimal combination of nutrient retention and low environmental damage. Insights from the study could be translated to support consumer decision-making as they weigh the value of environmental sustainability against nutrition in the context of household potato storage and processing.

Sustainable healthy diet modeling for a plant-based dietary transitioning in the United States.

The potential environmental and nutritional benefits of plant-based dietary shifts require thorough investigation to outline suitable routes to achieve these benefits. Whereas dietary consumption is usually in composite forms, sustainable healthy diet assessments have not adequately addressed composite diets. In this study, we build on available data in the Food4HealthyLife calculator to develop 3 dietary concepts (M) containing 24 model composite diet scenarios (S) assessed for their environmental and nutritional performances. The Health Nutritional Index (HENI) and Food Compass scoring systems were used for nutritional quality profiling and estimates of environmental impact were derived from previously reported midpoint impact values for foods listed in the What We Eat in America database. The diets were ranked using the Kruskal‒Wallis nonparametric test, and a dual-scale data chart was employed for a trade-off analysis to identify the optimal composite diet scenario. The results showcased a distinct variation in ranks for each scenario on the environment and nutrition scales, describing an inherent nonlinear relationship between environmental and nutritional performances. However, trade-off analysis revealed a diet with 10% legumes, 0.11% red meat, 0.28% processed meat and 2.81% white meat could reduce global warming by 54.72% while yielding a diet quality of 74.13 on the Food Compass Scoring system. These observations provide an interesting forecast of the benefits of transitioning to an optimal plant- and animal-based dieting pattern, which advances global nutritional needs and environmental stewardship among consumers.

Mechanisms involved in the coordinate regulation of mTORC1 by insulin and amino acids.

In this study, we explored the coordinate regulation of mTORC1 by insulin and amino acids. Rat livers were perfused with medium containing various concentrations of insulin and/or amino acids. At fasting (1×) or 2× (2×AA) concentrations of amino acids, insulin maximally stimulated Akt phosphorylation but had no effect on global rates of protein synthesis. In the absence of insulin, 4×AA produced a moderate stimulation of protein synthesis and activation of mTORC1. The combination of 4×AA and insulin produced a maximal stimulation of protein synthesis and activation of mTORC1. These effects were accompanied by decreases in raptor and PRAS40 and an increase in RagC associated with mTOR (mammalian target of rapamycin). The studies were extended to a cell culture model in which mTORC1 activity was repressed by deprivation of leucine and serum, and resupplementation with the amino acid and insulin acted in an additive manner to restore mTORC1 activation. In deprived cells, mTORC1 was activated by expressing either constitutively active (ca) Rheb or a caRagB·caRagC complex, and coexpression of the constructs had an additive effect. Notably, resupplementation with leucine in cells expressing caRheb or with insulin in cells expressing the caRagB·caRagC complex was as effective as resupplementation with both leucine and insulin in non-transfected cells. Moreover, changes in mTORC1 activity correlated directly with altered association of mTOR with RagB/RagC, Rheb, raptor, and PRAS40. Overall, the results suggest that amino acids signal through the Rag complex and insulin through Rheb to achieve coordinate activation of mTORC1.

The Effects of Maternal Intake of EPA and DHA Enriched Diet During Pregnancy and Lactation on Offspring's Muscle Development and Energy Homeostasis.

EPA and DHA are n-3 long-chain polyunsaturated fatty acids with a diversity of health benefits on offspring. The objective of this study was to test the in vivo effect of maternal ingestion of EPA and DHA on fetal and offspring muscle development and energy balance. Two groups of female C57BL/6 mice were fed EPA and DHA enriched diet (FA) and diet devoid of EPA and DHA (CON) respectively throughout the entire period of gestation and lactation. Embryos at E13 and offspring at age of D1 and D21 were selected for sample collection and processing. No change in birth number and body weight were observed between groups at D1 and D21. Transient increase in the expression levels of myogenesis regulating genes was detected at D1 (p < 0.05) in FA group. Most of the expression of muscle protein synthesis regulating genes were comparable (p > 0.05) between FA and CON groups at D1 and D21. The significant increase in MHC4, and IGF-1 was not linked to increased muscle mass. A persistent increase in ISR expression (p < 0.05) but not in GLUT-4 (p > 0.05) was detected in offspring. Up-regulation of adipogenesis regulating genes was accompanied by increasing intramuscular fat accumulation in the offspring of FA group. Considerable increase in transcripts of genes regulating lipid catabolism and thermogenesis in liver (p < 0.05) was noticed in FA group at D21; whereas, only the levels of carnitine palmitoyl transferase 1A (Cpt1α) and Enoyl-CoA Hydratase And 3-Hydroxyacyl CoA Dehydrogenase (Ehhadh) increased at D1. Similarly, genes regulating lipolysis were highly expressed at D21 in FA group. EPA and DHA treatment promoted BAT development and activity by increasing the expression of BAT signature genes (p < 0.05). Also, maternal intake of EPA and DHA enriched diet enhanced browning of sWAT. Taken together, maternal ingestion of EPA/DHA may be suggested as a therapeutic option to improve body composition and counteract childhood obesity- related metabolic disorders and confer lifelong positive metabolic impact on offspring.

Transitioning to sustainable healthy diets: A model-based and conceptual system thinking approach to optimized sustainable diet concepts in the United States.

Food production and consumption are essential in human existence, yet they are implicated in the high occurrences of preventable chronic diseases and environmental degradation. Although healthy food may not necessarily be sustainable and vice versa, there is an opportunity to make our food both healthy and sustainable. Attempts have been made to conceptualize how sustainable healthy food may be produced and consumed; however, available data suggest a rise in the prevalence of health-related and negative environmental consequences of our food supply. Thus, the transition from conceptual frameworks to implementing these concepts has not always been effective. This paper explores the relative environmental and health risks associated with highly consumed food groups and develops a methodological workflow for evaluating the sustainability of diet concepts in the context of different health, socio-economic and environmental indicators. In addition, we apply the multi-criteria decision-making techniques (an integrated Analytic Hierarchy Process- Technique for order preference by similarity to ideal solution (AHP-TOPSIS) model) to examine the health and environmental impact of selected sustainable healthy diet concepts implemented in the United States. The principal findings indicate that adopting plant-based diet patterns would benefit the environment and the population's health. However, the up-scale, broad adoption and implementation of these concepts are hindered by critical bottlenecks. Hence we propose potential modification strategies through a conceptual system thinking approach to deliver optimized sustainable diet concepts to aid in the realization of the anticipated benefits of adoption/implementation.

The Effects of Blueberry Phytochemicals on Cell Models of Inflammation and Oxidative Stress.

Blueberries have been extensively studied for the health benefits associated with their high phenolic content. The positive impact of blueberry consumption on human health is associated in part with modulation of proinflammatory molecular pathways and oxidative stress. Here, we review in vitro studies examining the anti-inflammatory and antioxidant effects of blueberry phytochemicals, discuss the results in terms of relevance to disease and health, and consider how different blueberry components modulate cellular mechanisms. The dampening effects of blueberry-derived molecules on inflammation and oxidative stress in cell models have been demonstrated through downregulation of the NF-κB pathway and reduction of reactive oxygen species (ROS) and lipid peroxidation. The modulatory effects of blueberry phytochemicals on the mitogen-activated protein kinase (MAPK) pathway and antioxidant system are not as well described, with inconsistent observations reported on immune cells and between models of endothelial, dermal, and ocular inflammation. Although anthocyanins are often reported as being the main bioactive compound in blueberries, no individual phytochemical has emerged as the primary compound when different fractions are compared; rather, an effect of whole blueberry extracts or synergy between different phenolic and nonphenolic extracts seems apparent. The major molecular mechanisms of blueberry phytochemicals are increasingly defined in cell models, but their relevance in more complex human systems needs further investigation using well-controlled clinical trials, in which systemic exposures to blueberry-associated molecules are measured concurrently with physiologic indices of inflammation and oxidative stress.

The potential role of beef and nutrients found in beef on outcomes of wellbeing in healthy adults 50 years of age and older: A systematic review of randomized controlled trials.

Shifts in wellbeing and health occur as we age. As life expectancy increases, maintenance of wellbeing and health becomes increasingly important. Nutrients found in beef are associated with outcomes of wellbeing such as physical and cognitive function, lean body mass, and mood in older adults and individuals with chronic disease. However, it is unclear how beef and nutrients found in beef impact wellbeing in healthy adults ≥50 years of age. This study systematically reviewed evidence linking the intake of beef and nutrients found in beef to markers of wellbeing in healthy adults. PubMed, CINAHL, and Web of Science were searched up to August 31, 2021 for eligible randomized controlled trials (RCTs). Nutrients included in the analysis were beef, red meat, dietary protein, essential amino acids, branched chain amino acids, tryptophan, arginine, cysteine, glycine, glutamate, vitamin B6, vitamin B12, choline, zinc, and iron. We identified nine RCTs with results from 55 measurements of markers of wellbeing. An overall positive effect was found of beef and beef's nutrients on wellbeing. There was an overall positive effect of amino acids and protein on wellbeing, with no effect of arginine, vitamin B-12, leucine, and zinc. Physical function was also influenced by beef and nutrients found in beef. Eight of the studies found focused on specific nutrients found in beef, and not beef itself in older adults with one or more chronic diseases. This study identified a need for further research regarding the effect of beef and nutrients found in beef on defined functional outcomes of wellbeing in healthy adults ≥50 years of age.

Dietary Protein Requirements in Children: Methods for Consideration.

The current protein requirement estimates in children were largely determined from studies using the nitrogen balance technique, which has been criticized for potentially underestimating protein needs. Indeed, recent advances in stable isotope techniques suggests protein requirement as much as 60% higher than current recommendations. Furthermore, there is not a separate recommendation for children who engage in higher levels of physical activity. The current evidence suggests that physical activity increases protein requirements to support accretion of lean body masses from adaptations to exercise. The indicator amino acid oxidation and the 15N-end product methods represent alternatives to the nitrogen balance technique for estimating protein requirements. Several newer methods, such as the virtual biopsy approach and 2H3-creatine dilution method could also be deployed to inform about pediatric protein requirements, although their validity and reproducibility is still under investigation. Based on the current evidence, the Dietary Reference Intakes for protein indicate that children 4-13 years and 14-18 years require 0.95 and 0.85 g·kg-1·day-1, respectively, based on the classic nitrogen balance technique. There are not enough published data to overturn these estimates; however, this is a much-needed area of research.

Net protein balance correlates with expression of autophagy, mitochondrial biogenesis, and fat metabolism-related genes in skeletal muscle from older adults.

The mechanisms leading to sarcopenia, the main cause for frailty in older adults, are still unclear. Autophagy and the ubiquitin-proteasome system (UPS) may play a role in mediating muscle protein breakdown related to sarcopenia. In addition to loss of muscle mass, compromised muscle performance observed in sarcopenic patients has been linked to muscle mitochondria dysfunction. Increased fat deposition and fat cell infiltration in muscle frequently seen in skeletal muscle of older adults may play an additional role for the pathogenesis of sarcopenia. Therefore, the first objective of this study was to understand differences in expression of genes related to autophagy, UPS, mitochondrial biogenesis, and fat metabolism in skeletal muscle of older adults compared with young adults. Our second objective was to determine the correlation between whole body protein kinetics (WBPK) and gene expression with age. Real-time quantitative PCR was used to determine the relative expression of targeted genes, and hierarchical regression analysis was used to determine if age had a moderating effect on the correlation between expression of targeted genes and WBPK. Increases in the expression of autophagy-related genes and fat metabolism-related genes were observed in muscle of older adults compared with young adults. In addition, age enhanced the negative correlations between mitochondrial biogenesis genes and net protein balance. These results suggest that dysregulated gene expression of mitochondrial biogenesis could play a role in muscle loss in older adults.

The Short-Term Effect of Whey Compared with Pea Protein on Appetite, Food Intake, and Energy Expenditure in Young and Older Men.

BACKGROUND: Diets higher in protein have been reported to improve age-related changes in body composition via increased energy expenditure, shifts in substrate oxidation (SO), and decreased appetite. However, how protein source (e.g., animal compared with plant protein) affects energy expenditure, appetite, and food intake as we age is unknown. OBJECTIVES: The objective of this study was to evaluate the effect of protein source as part of a high-protein breakfast on appetite, food intake, energy expenditure, and fat oxidation in young men (YM) compared with older men (OM). METHODS: This study used a randomized, single-blinded crossover design, with a 1-wk washout period between testing days. Fifteen YM (mean ± SD age: 25.2 ± 2.8 y) and 15 OM (67.7 ± 4.5 y), healthy adults, participated in the study. Participants arrived fasted and consumed an isocaloric, volume-matched, high-protein (40-g) test beverage made with either an animal [whey protein isolate (WPI)] or plant [pea protein isolate (PPI)] protein isolate source. Markers of appetite and energy expenditure were determined at baseline and over 4 h postprandial. RESULTS: There was a significant effect of time, age, and protein source on appetite (P < 0.05). There was no effect of protein source on plasma markers of appetite, food intake, energy expenditure, and SO. After controlling for body weight, OM had decreased energy expenditure (P < 0.05) and lower fat oxidation (P < 0.001) compared with YM. CONCLUSIONS: This study indicates that a high-protein breakfast containing WPI or PPI exerts comparable effects on appetite, energy expenditure, and 24-h energy intake in both young and older healthy adult men.This trial was registered at clinicaltrials.gov as NCT03399812.

Glucagon acts in a dominant manner to repress insulin-induced mammalian target of rapamycin complex 1 signaling in perfused rat liver.

The opposing actions of insulin and glucagon on hepatic carbohydrate metabolism are well documented. In contrast, relatively little is known about how the two hormones interact to regulate hepatic protein metabolism. Previously, we reported that glucagon in the absence of insulin represses signaling through the mammalian target of rapamycin complex 1 (mTORC1). In the present study, we sought to determine whether or not the action of one hormone would dominate over the other in the regulation of mTORC1 signaling. Livers were perfused in situ with medium containing either no added hormones (control), 10 nM insulin, 100 nM glucagon, or a combination of the hormones. Compared with control livers, insulin stimulated Akt phosphorylation and mTORC1 signaling, as assessed by increased phosphorylation of the mTORC1 targets eIF4E-binding protein (4E-BP)1 and ribosomal protein S6 kinase (S6K)1, and promoted assembly of the eIF4G x eIF4E complex. Glucagon alone had no effect on mTORC1 signaling but stimulated the activity of protein kinase A (PKA). In the presence of a combination of insulin and glucagon, Akt and TSC2 phosphorylation and PKA activity were all increased compared with controls. However, mTORC1 signaling was repressed compared with livers perfused with medium containing insulin alone, and this effect was associated with reduced assembly of the mTORC1 x eIF3 complex. Overall, the results suggest that glucagon acts in a dominant manner to repress insulin-induced mTORC1 signaling, which is in contrast to previous studies showing a dominant action of insulin in the control of hepatic gluconeogenesis.

Effect of Eicosapentaenoic Acid and Docosahexaenoic Acid on Myogenesis and Mitochondrial Biosynthesis during Murine Skeletal Muscle Cell Differentiation.

Polyunsaturated fatty acids are important nutrients for human health, especially omega-3 fatty acids such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which have been found to play positive roles in the prevention of various diseases. However, previous studies have reported that excessive omega-3 fatty acids supplement during pregnancy caused side effects such as slower neural transmission times and postnatal growth restriction. In this study, we investigated the effect of EPA and DHA on mitochondrial function and gene expression in C2C12 myoblasts during skeletal muscle differentiation. C2C12 myoblasts were cultured to confluency and then treated with differentiation medium that contained fatty acids (50-µM EPA and DHA). After 72 h of myogenic differentiation, mRNA was collected, and gene expression was analyzed by real-time PCR. Microscopy was used to examine cell morphology following treatment with fatty acids. The effect of EPA and DHA on cellular oxygen consumption was measured using a Seahorse XF24 Analyzer. Cells treated with fatty acids had fewer myotubes formed (P ≤ 0.05) compared with control cells. The expression of the genes related to myogenesis was significantly lower (P ≤ 0.05) in cells treated with fatty acids, compared with control cells. Genes associated with adipogenesis had higher (P ≤ 0.05) expression after treatment with fatty acids. Also, the mitochondrial biogenesis decreased with lower (P ≤ 0.05) gene expression and lower (P ≤ 0.05) mtDNA/nDNA ratio in cells treated with fatty acids compared with control cells. However, the expression of genes related to peroxisome biosynthesis was higher (P ≤ 0.05) in cells treated with fatty acids. Moreover, fatty-acid treatment reduced (P ≤ 0.05) oxygen consumption rate under oligomycin-inhibited (reflecting proton leak) and uncoupled conditions. Our data imply that fatty acids might reduce myogenesis and increase adipogenesis in myotube formation. Fatty acids may also decrease cell metabolism by reducing mitochondrial biogenesis as well as respiration rate. This study suggests that the maternal overdosage of EPA and DHA may influence fetal muscle development, increase intramuscular adipose tissue deposition in offspring, and have a long-term effect on the development of metabolic diseases such as obesity and diabetes in adult offspring.

Factors contributing to the selection of dietary protein food sources.

Protein is the only dietary macronutrient required for life. As such, it is reasonable to consider dietary protein as the centerpiece of a healthy eating pattern. To do so requires consideration of what type of protein should be eaten. Account should be taken of the quality of the protein, the density of the protein in the protein food source, and the non-protein components of protein food source. The quality of protein can be quantified based on the amount and profile of essential amino acids (EAAs), as well as the true ileal digestibility of the EAAs in the protein. The density of protein in a food source can be quantified on the basis of the amount of total calories ingested to achieve intake of the daily requirement of all EAAs. Non-protein components of protein food sources can be considered in terms of the amount and nature of fat, carbohydrate and fiber, as well as the content of micronutrients. Potential beneficial effects of high-quality protein food sources should be balanced against any possible adverse effects. When all of these factors are considered we conclude that animal-based protein foods (e.g., eggs, dairy, meat, fish, poultry) occupy an important place in a healthy eating pattern.