Ingestion of a protein hydrolysate is accompanied by an accelerated in vivo digestion and absorption rate when compared with its intact protein

MURAMYL DIPEPTIDE CAUSES MITOCHONDRIAL DYSFUNCTION AND INTESTINAL INFLAMMATORY CYTOKINE RESPONSES IN RATS

ABSTRACT

Introduction: Intestinal flora and the translocation of its products, such as muramyl dipeptide (MDP), are common causes of sepsis. MDP is a common activator of the intracellular pattern recognition receptor NOD2, and MDP translocation can cause inflammatory damage to the small intestine and systemic inflammatory responses in rats. Therefore, this study investigated the effects of MDP on the intestinal mucosa and distant organs during sepsis and the role of the NOD2/AMPK/LC3 pathway in MDP-induced mitochondrial dysfunction in the intestinal epithelium. Methods: Fifty male Sprague Dawley rats were randomly divided into five treatment groups: lipopolysaccharide (LPS) only, 1.5 and 15 mg/kg MDP+LPS, and 1.5 and 15 mg/kg MDP+short-peptide enteral nutrition (SPEN)+LPS. The total caloric intake was the same per group. The rats were euthanized 24 h after establishing the model, and peripheral blood and small intestinal mucosal and lung tissues were collected. Results: Compared to the LPS group, both MDP+LPS groups had aggravated inflammatory damage to the intestinal mucosal and lung tissues, increased IL-6 and MDP production, increased NOD2 expression, decreased AMPK and LC3 expression, increased mitochondrial reactive oxygen species production, and decreased mitochondrial membrane potential. Compared to the MDP+LPS groups, the MDP+SPEN+LPS groups had decreased IL-6 and MDP production, increased AMPK and LC3 protein expression, and protected mitochondrial and organ functions. Conclusions: MDP translocation reduced mitochondrial autophagy by regulating the NOD2/AMPK/LC3 pathway, causing mitochondrial dysfunction. SPEN protected against MDP-induced impairment of intestinal epithelial mitochondrial function during sepsis.

Reconsidering the pre-eminence of dietary leucine and plasma leucinemia for predicting the stimulation of postprandial muscle protein synthesis rates

The regulation of postprandial muscle protein synthesis (MPS) with or without physical activity has been an intensely studied area within nutrition and physiology. The leucine content of dietary protein and the subsequent plasma leucinemia it elicits postingestion is often considered the primary drivers of the postprandial MPS response. This concept, generally known as the leucine "trigger" hypothesis, has also been adopted within more applied aspects of nutrition. Our view is that recent evidence is driving a more nuanced picture of the regulation of postprandial MPS by revealing a compelling dissociation between ingested leucine or plasma leucinemia and the magnitude of the postprandial MPS response. Much of this lack of coherence has arisen as experimental progress has demanded relevant studies move beyond reliance on isolated amino acids and proteins to use increasingly complex protein-rich meals, whole foods, and mixed meals. Our overreliance on the centrality of leucine in this field has been reflected in 2 recent systematic reviews. In this perspective, we propose a re-evaluation of the pre-eminent role of these leucine variables in the stimulation of postprandial MPS. We view the development of a more complex intellectual framework now a priority if we are to see continued progress concerning the mechanistic regulation of postprandial muscle protein turnover, but also consequential from an applied perspective when evaluating the value of novel dietary protein sources.

The impact of heat treatment of bovine milk on gastric emptying and nutrient appearance in peripheral circulation in healthy females: a randomized controlled trial comparing pasteurized and ultra-high temperature milk

BACKGROUND

Heat treatments of dairy, including pasteurization and ultra-high temperature (UHT) processing, alter milk macromolecular structures, and ultimately affect digestion. In vitro, animal, and human studies show faster nutrient release or circulating appearance after consuming UHT milk (UHT-M) compared with pasteurized milk (PAST-M), with a faster gastric emptying (GE) rate proposed as a possible mechanism.

OBJECTIVES

To investigate the impact of milk heat treatment on GE as a mechanism of faster nutrient appearance in blood. We hypothesized that GE and circulating nutrient delivery following consumption would be faster for UHT-M than PAST-M.

METHODS

In this double-blind randomized controlled cross-over trial, healthy female (n = 20; 27.3 ± 1.4 y, mean ± SD) habitual dairy consumers, consumed 500 mL of either homogenized bovine UHT-M or PAST-M (1340 compared with 1320 kJ). Gastric content volume (GCV) emptying half-time (T50) was assessed over 3 h by magnetic resonance imaging subjective digestive symptoms, plasma amino acid, lipid and B vitamin concentrations, and gastric myoelectrical activity were measured over 5 h.

RESULTS

Although GCV T50 did not differ (102 ± 7 min compared with 89 ± 8 min, mean ± SEM, UHT-M and PAST-M, respectively; P = 0.051), GCV time to emptying 25% of the volume was 31% longer following UHT-M compared with PAST-M (42 ± 2 compared with 32 ± 4 min, P = 0.004). Although GCV remained larger for a longer duration following UHT-M (treatment × time interaction, P = 0.002), plasma essential amino acid AUC was greater following UHT-M than PAST-M (55,324 ± 3809 compared with 36,598 ± 5673 μmol·min·L-1, P = 0.006). Heat treatment did not impact gastric myoelectrical activity, plasma appetite hormone markers or subjective appetite scores.

CONCLUSIONS

Contrary to expectations, GE was slower with UHT-M, yet, as anticipated, aminoacidemia was greater. The larger GCV following UHT-M suggests that gastric volume may poorly predict circulating nutrient appearance from complex food matrices. Dairy heat treatment may be an effective tool to modify nutrient release by impacting digestion kinetics.

CLINICAL TRIAL REGISTRY

www.anzctr.org.au (ACTRN12620000172909).

Whey protein hydrolysates and infant formulas: Effects on physicochemical and biological properties

Whey protein hydrolysates are recognized for their substantial functional and biological properties. Their high digestibility and amino acid composition make them a valuable ingredient to hydrolyzed whey infant formulas, enhancing both product functionality and nutritional values for infant growth. It is important to understand the functional and biological properties of whey protein hydrolysates for their applications in infant formula systems. This review explored preparation methods of whey protein hydrolysates for infant formula-based applications. The effects of whey protein hydrolysate on the physicochemical and biological properties of hydrolyzed whey infant formulas were summarized. The influences of whey protein hydrolysates on the functional and nutritional properties of formulas from manufacturing to infant consumption were discussed. Whey protein hydrolysates are crucial components in the preparation of infant formula, tailored to meet the functional and nutritional demands of the product. The selection of enzyme types and hydrolysis parameters is decisive for obtaining "optimal" whey protein hydrolysates that match the intended characteristics. "Optimal" whey protein hydrolysates offer diverse functionalities, including solubility, emulsification and production stability to hydrolyzed whey infant formulas during manufacturing processes and formulations. They simultaneously promote protein digestibility, infant growth and other potential health benefits, including reduced allergenic potential, as supported by in vitro, in vivo and clinical trials. Overall, the precise selection of enzymes and hydrolysis parameters in the production of whey protein hydrolysates is crucial in achieving the desired characteristics and functional benefits for hydrolyzed whey infant formulas, making them critical in the development of infant nutrition products.

Do high-protein diets have the potential to reduce gut barrier function in a sex-dependent manner?

PURPOSE

Impaired gut barrier function is associated with systemic inflammation and many chronic diseases. Undigested dietary proteins are fermented in the colon by the gut microbiota which produces nitrogenous metabolites shown to reduce barrier function in vitro. With growing evidence of sex-based differences in gut microbiotas, we determined whether there were sex by dietary protein interactions which could differentially impact barrier function via microbiota modification.

METHODS

Fermentation systems were inoculated with faeces from healthy males (n = 5) and females (n = 5) and supplemented with 0.9 g of non-hydrolysed proteins sourced from whey, fish, milk, soya, egg, pea, or mycoprotein. Microbial populations were quantified using fluorescence in situ hybridisation with flow cytometry. Metabolite concentrations were analysed using gas chromatography, solid phase microextraction coupled with gas chromatography-mass spectrometry and ELISA.

RESULTS

Increased protein availability resulted in increased proteolytic Bacteroides spp (p < 0.01) and Clostridium coccoides (p < 0.01), along with increased phenol (p < 0.01), p-cresol (p < 0.01), indole (p = 0.018) and ammonia (p < 0.01), varying by protein type. Counts of Clostridium cluster IX (p = 0.03) and concentration of p-cresol (p = 0.025) increased in males, while females produced more ammonia (p = 0.02), irrespective of protein type. Further, we observed significant sex-protein interactions affecting bacterial populations and metabolites (p < 0.005).

CONCLUSIONS

Our findings suggest that protein fermentation by the gut microbiota in vitro is influenced by both protein source and the donor's sex. Should these results be confirmed through human studies, they could have major implications for developing dietary recommendations tailored by sex to prevent chronic illnesses.

Metabolic Syndrome and Biotherapeutic Activity of Dairy (Cow and Buffalo) Milk Proteins and Peptides: Fast Food-Induced Obesity Perspective-A Narrative Review

Metabolic syndrome (MS) is defined by the outcome of interconnected metabolic factors that directly increase the prevalence of obesity and other metabolic diseases. Currently, obesity is considered one of the most relevant topics of discussion because an epidemic heave of the incidence of obesity in both developing and underdeveloped countries has been reached. According to the World Obesity Atlas 2023 report, 38% of the world population are presently either obese or overweight. One of the causes of obesity is an imbalance of energy intake and energy expenditure, where nutritional imbalance due to consumption of high-calorie fast foods play a pivotal role. The dynamic interactions among different risk factors of obesity are highly complex; however, the underpinnings of hyperglycemia and dyslipidemia for obesity incidence are recognized. Fast foods, primarily composed of soluble carbohydrates, non-nutritive artificial sweeteners, saturated fats, and complexes of macronutrients (protein-carbohydrate, starch-lipid, starch-lipid-protein) provide high metabolic calories. Several experimental studies have pointed out that dairy proteins and peptides may modulate the activities of risk factors of obesity. To justify the results precisely, peptides from dairy milk proteins were synthesized under in vitro conditions and their contributions to biomarkers of obesity were assessed. Comprehensive information about the impact of proteins and peptides from dairy milks on fast food-induced obesity is presented in this narrative review article.

Administration of Free Amino Acids Improves Exogenous Amino Acid Availability when Compared with Intact Protein in Critically Ill Patients: A Randomized Controlled Study

BACKGROUND

Protein digestion and amino acid absorption appear compromised in critical illness. The provision of enteral feeds with free amino acids rather than intact protein may improve postprandial amino acid availability.

OBJECTIVE

Our objective was to quantify the uptake of diet-derived phenylalanine after the enteral administration of intact protein compared with an equivalent amount of free amino acids in critically ill patients.

METHODS

Sixteen patients who were mechanically ventilated in intensive care unit (ICU) at risk of malabsorption received a primed continuous infusion of L-[ring-2H5]-phenylalanine and L-[ring-3,5-2H2]-tyrosine after an overnight fast. Patients were randomly allocated to receive 20 g intrinsically L-[1-13C]-phenylalanine-labeled milk protein or an equivalent amount of amino acids labeled with free L-[1-13C]-phenylalanine via a nasogastric tube over a 2-h period. Protein digestion and amino acid absorption kinetics and whole-body protein net balance were assessed throughout a 6-h period.

RESULTS

After enteral nutrient infusion, both plasma phenylalanine and leucine concentrations increased (P-time < 0.001), with a more rapid and greater rise after free amino acid compared with intact protein administration (P-time × treatment = 0.003). Diet-derived phenylalanine released into the circulation was 25% greater after free amino acids compared with intact protein administration [68.7% (confidence interval {CI}: 62.3, 75.1%) compared with 43.8% (CI: 32.4, 55.2%), respectively; P < 0.001]. Whole-body protein net balance became positive after nutrient administration (P-time < 0.001) and tended to be more positive after free amino acid in provision (P-time × treatment = 0.07).

CONCLUSIONS

The administration of free amino acids as opposed to intact protein further increases postprandial plasma amino acid availability in critically ill patients, allowing more diet-derived phenylalanine to become available to peripheral tissues. This trial was registered at clinicaltrials.gov as NCT04791774.

Improved digestibility and bioavailability of pea protein following enzymatic treatment and fermentation by lactic acid bacteria

Peas (Pisum sativum L.) have a potential commercial value because of their high protein content, non-GMO status, low allergenicity. This study examined changes in the digestion and absorption properties of enzyme-modified and fermented pea protein (EFPP) produced through enzymatic treatment of pea protein and fermentation with lactic acid bacteria. EFPP was digested 22.50% more than isolated pea protein (IPP) during the first 15 min in vitro digestion model. Based on the Caco-2 cell monolayer model, EFPP showed 38.40% higher bioavailability than IPP. Gel Permeation Chromatography showed that the average molecular weight of EFPP was 98.79% lower than that of IPP. The secondary structure of protein was analyzed by Fourier transform infrared spectrometry and it showed a 53.92% reduction in β-sheet of EFPP than IPP. These results indicate that enzyme treatment and fermentation of pea protein reduced the molecular weight, modified the secondary structure, and improved digestibility and bioavailability.

Protein Hydrolysates and Bioactive Peptides as Mediators of Blood Glucose-A Systematic Review and Meta-Analysis of Acute and Long-Term Studies

Type 2 diabetes mellitus (T2DM) is a major public health concern associated with high mortality and reduced life expectancy. Since diabetes is closely linked with lifestyle, not surprisingly, nutritional intervention and increased physical activity could play a vital role in attenuating the problems related to diabetes. Protein hydrolysates (PHs) and their bioactive peptides (BP) have been shown to exert a wide range of biological effects, including antioxidative, antihypertensive, and in particular, hypoglycaemic activities. To better understand the efficacy of such interventions, a systematic review and meta-analysis of randomised controlled trials (RCTs) were performed concerning the influence of protein hydrolysates on glycaemic biomarkers in subjects with and without hyperglycaemia. Five different databases were used to search for RCTs. In total, 37 RCTs were included in the systematic review and 29 RCTs in the meta-analysis. The meta-analysis revealed a significant reduction in postprandial blood glucose response (PPGR) in normoglycaemic (-0.22 mmol/L; 95% CI -0.43, -0.01; p ≤ 0.05) and in hyperglycaemic adults (-0.88 mmol/L; 95% CI -1.37, -0.39; p ≤ 0.001) compared with the respective control groups. A meta-regression analysis revealed a dose-dependent response for PPGR following PH consumption in normoglycaemic adults, specifically for doses ≤ 30 g. The postprandial blood insulin responses (PPIR) were significantly higher after the ingestion of PHs in both the group with and the group without hyperglycaemia, respectively (23.05 mIU/L; 95% CI 7.53, 38.57; p ≤ 0.01 and 12.57 mIU/L; 95% CI 2.72, 22.41; p ≤ 0.01), compared with controls. In terms of long-term responses, there was a small but significant reduction in both fasting blood glucose (FBG) and fasting glycated haemoglobin (HbA1c) in response to PH compared with the control group (p < 0.05). The PHs significantly improved the parameters of glycaemia in adults and, hence, it may contribute to the management and regulation of the future risk of developing T2DM.

Nasogastric bolus administration of a protein-rich drink augments insulinaemia and aminoacidaemia but not whole-body protein turnover or muscle protein synthesis versus oral administration

Nasogastric feeding of protein-rich liquids is a nutritional support therapy that attenuates muscle mass loss. However, whether administration via a nasogastric tube per se augments whole-body or muscle protein anabolism compared with oral administration is unknown. Healthy participants were administered a protein-rich drink (225 ml containing 21 g protein) orally (ORAL; n=13; age 21 ± 1 year; BMI 22.2 ± 0.6 kg·m-2) or via a nasogastric tube (NG; n=13; age 21 ± 1 yr; BMI 23.9 ± 0.9 kg·m-2) in a parallel group design, balanced for sex. L-[ring-2H5]-phenylalanine and L-[3,3-2H2]-tyrosine were infused to measure postabsorptive and postprandial whole-body protein turnover. Skeletal muscle biopsies were collected at -120, 0, 120 and 300 min relative to drink administration to quantify temporal myofibrillar fractional synthetic rates (myoFSR). Drink administration increased serum insulin and plasma amino acid concentrations, and to a greater extent and duration in NG versus ORAL (all interactions P<0.05). Drink administration increased whole-body protein synthesis (P<0.01), suppressed protein breakdown (P<0.001), and created positive net protein balance (P<0.001), but to a similar degree in ORAL and NG (interactions P>0.05). Drink administration increased myoFSR from the postabsorptive state (P<0.01), regardless of route of administration in ORAL and in NG (interaction P>0.05). Nasogastric bolus administration of a protein-rich drink induces insulinaemia and aminoacidaemia to a greater extent than oral administration, but the postprandial increase in whole-body protein turnover and muscle protein synthesis was equivalent between administration routes. Nasogastric administration is a potent intervention to increase postprandial amino acid availability. Future work should assess its utility in overcoming impaired sensitivity to protein feeding, such as that seen in ageing, disuse, and critical care.

Enteral feeding strategies in patients with acute gastrointestinal injury: From limited to progressive to open feeding

Acute gastrointestinal injury (AGI) is very common in critically ill patients, and its severity is positively correlated with mortality. Critically ill patients with digestive and absorption dysfunction caused by AGI face higher nutritional risks, making nutritional support particularly important. Early enteral nutrition (EN) support is extremely important because it can promote the recovery of intestinal function, protect the intestinal mucosal barrier, reduce microbiota translocation, reduce postoperative complications, shorten hospital stay, and improve clinical prognosis. In recent years, many nutritional guidelines have been proposed for critically ill patients; however, there are few recommendations for the implementation of EN in patients with AGI, and their quality of evidence is low. The use of EN feeding strategies in critically ill patients with AGI remains controversial. The aim of this review was to elaborate on how EN feeding strategies should transition from limited to progressive to open feeding and explain the time window for this transition.

The effect of pre-exercise protein intake on substrate metabolism, energy expenditure, and energy intake: a dose-response study

BACKGROUND

Pre-exercise protein consumption does not seem to influence substrate metabolism during exercise compared to fasted exercise, however it is unclear if the protein dose impacts on this effect.

METHODS

In a randomized, double-blinded within-subject design trial, healthy, active males and females (n = 15, 25 ± 5 yrs, O2peak: 47.5 ± 8.8 ml/kg/min) completed 1 h of cycling exercise at 60% peak power output 30 min after having consumed either 0, 20, or 40 g of whey protein. Indirect calorimetry was used to measure substrate oxidation during exercise and baseline and post-exercise resting energy expenditure. Blood samples were taken throughout the trials to measure metabolic responses. Free-living food intake post-trial was collected using food diaries.

RESULTS

Fat oxidation rates during exercise did not differ between the three conditions (p = 0.19) with small effect sizes between conditions (Cohen's dz: 0 vs. 20 g = 0.22, 0 vs. 40 g = 0.47, 20 vs. 40 g = 0.27). Serum insulin was higher in the protein groups vs. 0 g (p < 0.05), whereas non-esterified fatty acids were higher in the 0 g compared to 20 and 40 g (p < 0.05). Glucose was significantly lower after 15 min of exercise in 20 and 40 g vs. 0 g (p = 0.01). Resting energy expenditure was elevated post-exercise (p < 0.001), without an interaction for protein dose (p = 0.90). Post-trial free-living energy intake was not different between conditions (p = 0.31), but 24-h energy intake was significantly higher in 40 vs. 0 g (p = 0.04).

CONCLUSION

Protein doses up to 40 g do not seem to impair fat oxidation rates during exercise compared to fasted exercise and could be considered as a nutritional strategy for exercising individuals who struggle to include fasted exercise in their training.

Protein digestion and absorption: the influence of food processing

The rates of dietary protein digestion and absorption can be significantly increased or decreased by food processing treatments such as heating, gelling and enzymatic hydrolysis, with subsequent metabolic impacts, e.g. on muscle synthesis and glucose homeostasis.This review examines in vivo evidence that industrial and domestic food processing modify the kinetics of amino acid release and absorption following a protein-rich meal. It focuses on studies that used compositionally-matched test meals processed in different ways.Food processing at extremely high temperature at alkaline pH and/or in the presence of reducing sugars can modify amino acid sidechains, leading to loss of bioavailability. Some protein-rich food ingredients are deliberately aggregated, gelled or hydrolysed during manufacture. Hydrolysis accelerates protein digestion/absorption and increases splanchnic utilisation. Aggregation and gelation may slow or accelerate proteolysis in the gut, depending on the aggregate/gel microstructure.Milk, beef and eggs are heat processed prior to consumption to eliminate pathogens and improve palatability. The temperature and time of heating affect protein digestion and absorption rates, and effects are sometimes non-linear. In light of a dietary transition away from animal proteins, more research is needed on how food processing affects digestion and absorption of non-animal proteins.Food processing modifies the microstructure of protein-rich foods, and thereby alters protein digestion and absorption kinetics in the stomach and small intestine. Exploiting this principle to optimise metabolic outcomes requires more human clinical trials in which amino acid absorption rates are measured and food microstructure is explicitly considered, measured and manipulated.

Behaviour of texture-modified meats using proteolytic enzymes during gastrointestinal digestion simulating elderly alterations

This study aimed to apply different proteolytic enzymes (bromelain, papain, and flavourzyme) to develop texture-modified meats suitable for people with chewing or swallowing problems. The samples were categorised at level 6 (soft and bite-sized food) of the dysphagia diet, characterised in terms of physicochemical and textural parameters, and evaluated for their behaviour during gastrointestinal digestion simulating elderly alterations. In general, the enzyme-treated samples had lower moisture content, weight, and diameter of the piece of meat, and presented colour differences compared to the control samples. Textural analyses did not show significant differences in terms of hardness and cohesiveness for the texture-modified meats, while flavourzyme-treated samples presented less elasticity. Instrumental mastication assay showed the breakdown of samples' structure mainly during the first mastication cycles, with flavourzyme-treated samples presenting slightly higher consistency. The protein digestibility of the meats greatly increased after simulated gastrointestinal digestion, but a decrease in proteolysis for the control and papain-treated samples in the altered gastric model and an increase for flavourzyme-treated samples in the altered both gastric and intestinal model were shown compared to standard conditions. These results allow integrating knowledge to design foods that better meet the requirements of dysphagics or elderly people.

Algae Ingestion Increases Resting and Exercised Myofibrillar Protein Synthesis Rates to a Similar Extent as Mycoprotein in Young Adults

BACKGROUND

Spirulina [SPIR] (cyanobacterium) and chlorella [CHLO] (microalgae) are foods rich in protein and essential amino acids; however, their capacity to stimulate myofibrillar protein synthesis (MyoPS) in humans remains unknown.

OBJECTIVES

We assessed the impact of ingesting SPIR and CHLO compared with an established high-quality nonanimal-derived dietary protein source (fungal-derived mycoprotein [MYCO]) on plasma amino acid concentrations, as well as resting and postexercise MyoPS rates in young adults.

METHODS

Thirty-six healthy young adults (age: 22 ± 3 y; BMI: 23 ± 3 kg·m-2; male [m]/female [f], 18/18) participated in a randomized, double-blind, parallel-group trial. Participants received a primed, continuous infusion of L-[ring-2H5]-phenylalanine and completed a bout of unilateral-resistance leg exercise before ingesting a drink containing 25 g protein from MYCO (n = 12; m/f, 6/6), SPIR (n = 12; m/f, 6/6), or CHLO (n = 12; m/f, 6/6). Blood and bilateral muscle samples were collected at baseline and during a 4-h postprandial and postexercise period to assess the plasma amino acid concentrations and MyoPS rates in rested and exercised tissue.

RESULTS

Protein ingestion increased the plasma total and essential amino acid concentrations (time effects; all P < 0.001), but most rapidly and with higher peak responses following the ingestion of SPIR compared with MYCO and CHLO (P < 0.05), and MYCO compared with CHLO (P < 0.05). Protein ingestion increased MyoPS rates (time effect; P < 0.001) in both rested (MYCO, from 0.041 ± 0.032 to 0.060 ± 0.015%·h-1; SPIR, from 0.042 ± 0.030 to 0.066 ± 0.022%·h-1; and CHLO, from 0.037 ± 0.007 to 0.055 ± 0.019%·h-1, respectively) and exercised tissue (MYCO, from 0.046 ± 0.014 to 0.092 ± 0.024%·h-1; SPIR, from 0.038 ± 0.011 to 0.086 ± 0.028%·h-1; and CHLO, from 0.048 ± 0.019 to 0.090 ± 0.024%·h-1, respectively), with no differences between groups (interaction effect; P > 0.05), but with higher rates in exercised compared with rested muscle (time × exercise effect; P < 0.001).

CONCLUSIONS

The ingestion of a single bolus of algae-derived SPIR and CHLO increases resting and postexercise MyoPS rates to a comparable extent as MYCO, despite divergent postprandial plasma amino acid responses.

Small peptide formulas versus standard polymeric formulas in critically ill patients with acute gastrointestinal injury: a systematic review and meta-analysis

Small peptide formulas versus standard polymeric formulas for enteral nutrition in critically ill patients with acute gastrointestinal injury (AGI) have been a topic of debate. A systematic review and meta-analysis were conducted to compare their clinical and nutritional outcomes. Relevant studies from January 1980 to June 2022 were searched in PubMed, Cochrane, and Embase databases. Randomized controlled trials involving AGI grade I-IV patients were included, while children, non-AGI patients, and non-critically ill patients were excluded. Results indicated no significant difference in all-cause mortality. Patients receiving small peptide formulas showed higher daily protein intake, greater albumin growth, and higher prealbumin levels. They also had shorter lengths of stay in the intensive care unit and hospital. Conversely, patients receiving standard polymeric formulas had a higher daily calorie intake. In conclusion, the choice of formula may not affect mortality in critically ill patients with AGI. Small peptide formulas were more conducive to increase daily protein intake, decrease intensive care unit and hospital length of stay. Further large-scale randomized controlled trials evaluating the effects of these two nutritional formulas on clinical and nutritional outcomes in critically ill patients with AGI are needed to confirm these results.

Protein-based nutritional strategies to manage the development of diabetes: evidence and challenges in human studies

Type 2 diabetes mellitus (T2DM) is one of the most prevalent diseases in modern society, governed by both genetic and environmental factors, such as nutritional habits. This metabolic disorder is characterized by insulin resistance, which is related to high blood glucose levels, implying negative health effects in humans, hindering the healthy ageing of people. The relationship between food and health is clear, and the ingestion of specific nutrients modulates some physiological processes, potentially implying biologically relevant changes, which can translate into a health benefit. This review aims to summarize human studies published in which the purpose was to investigate the effect of protein ingestion (in native state or as hydrolysates) on human metabolism. Overall, several studies showed how protein ingestion might induce a decrease of glucose concentration in the postprandial state (area under the curve), although it is highly dependent on the source and the dose. Other studies showed no biological effects upon protein consumption, mostly with fish-derived products. In addition, the major challenges and perspectives in this research field are highlighted, suggesting the future directions, towards which scientists should focus on. The dietary intake of proteins has been proven to likely exert a beneficial effect on diabetes-related parameters, which can have a biological relevance in the prevention and pre-treatment of diabetes. However, the number of well-designed human studies carried out to date to demonstrate the effects of specific proteins or protein hydrolysates in vivo is still scarce.

Digestion-resistant whey peptides promote antioxidant effect on Caco-2 cells

Enteric endothelial cells are the first structure to come in contact with digested food and may suffer oxidative damage by innumerous exogenous factors. Although peptides derived from whey digestion have presented antioxidant potential, little is known regarding antioxidant pathways activation in Caco-2 cell line model. Hence, we evaluated the ability to form whey peptides resistant to simulated gastrointestinal digestive processes, with potential antioxidant activity on gastrointestinal cells and associated with sequence structure and activity. Using the INFOGEST method of simulated static digestion, we achieved 35.2% proteolysis, with formation of peptides of low molecular mass (<600 Da) evaluated by FPLC. The digestion-resistant peptides showed a high proportion of hydrophobic and acidic amino acids, but with average surface hydrophobicity. We identified 24 peptide sequences, mainly originated from β-lactoglobulin, that exhibit various bioactivities. Structurally, the sequenced peptides predominantly contained the amino acids lysine and valine in the N-terminal region, and tyrosine in the C-terminal region, which are known to exhibit antioxidant properties. The antioxidant activity of the peptide digests was on average twice as potent as that of the protein isolates for the same concentration, as evaluated by ABTS, DPPH and ORAC. Evaluation of biological activity in Caco-2 intestinal cells, stimulated with hydrogen peroxide, showed that they attenuated the production of reactive oxygen species and prevented GSH reduction and SOD activity increase. Caco-2 cells were not responsive to nitric oxide secretion. This study suggests that whey peptides formed during gastric digestion exhibit biological antioxidant activity, without the need for previously hydrolysis with exogenous enzymes for supplement application. The study's primary contribution was demonstrating the antioxidant activity of whey peptides in maintaining the gastrointestinal epithelial cells, potentially preventing oxidative stress that affects the digestive system.

A focus on leucine in the nutritional regulation of human skeletal muscle metabolism in ageing, exercise and unloading states

Muscle protein synthesis (MPS) and muscle protein breakdown (MPB) are influenced through dietary protein intake and physical (in)activity, which it follows, regulate skeletal muscle (SKM) mass across the lifespan. Following consumption of dietary protein, the bio-availability of essential amino acids (EAA), and primarily leucine (LEU), drive a transient increase in MPS with an ensuing refractory period before the next MPS stimulation is possible (due to the "muscle full" state). At the same time, MPB is periodically constrained via reflex insulin actions. Layering exercise on top of protein intake increases the sensitivity of SKM to EAA, therefore extending the muscle full set-point (∼48 h), to permit long-term remodelling (e.g., hypertrophy). In contrast, ageing and physical inactivity are associated with a premature muscle full set-point in response to dietary protein/EAA and contractile activity. Of all the EAA, LEU is the most potent stimulator of the mechanistic target of rapamycin complex 1 (mTORC1)-signalling pathway, with the phosphorylation of mTORC1 substrates increasing ∼3-fold more than with all other EAA. Furthermore, maximal MPS stimulation is also achieved following low doses of LEU-enriched protein/EAA, negating the need for larger protein doses. As a result, LEU supplementation has been of long term interest to maximise muscle anabolism and subsequent net protein accretion, especially when in tandem with resistance exercise. This review highlights current knowledge vis-à-vis the anabolic effects of LEU supplementation in isolation, and in enriched protein/EAA sources (i.e., EAA and/or protein sources with added LEU), in the context of ageing, exercise and unloading states.

CCK and GLP-1 response on enteroendocrine cells of semi-dynamic digests of hydrolyzed and intact casein

A semi-dynamic gastrointestinal device was employed to explore the link between protein structure and metabolic response upon digestion for two different substrates, a casein hydrolysate and the precursor micellar casein. As expected, casein formed a firm coagulum that remained until the end of the gastric phase while the hydrolysate did not develop any visible aggregate. Each gastric emptying point was subjected to a static intestinal phase where the peptide and amino acid composition changed drastically from that found during the gastric phase. Gastrointestinal digests from the hydrolysate were characterized by a high abundancy of resistant peptides and free amino acids. Although all gastric and intestinal digests from both substrates induced the secretion of cholecystokinin (CCK) and glucagon-like peptide-1 (GLP-1) in STC-1 cells, GLP-1 levels were maximum in response to gastrointestinal digests from the hydrolysate. The enrichment of protein ingredients with gastric-resistant peptides by enzymatic hydrolysis is proposed as strategy to deliver protein stimuli to the distal gastrointestinal tract to control food intake or type 2 diabetes.

The role of human milk nutrients in preventing necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is an intestinal disease that primarily impacts preterm infants. The pathophysiology of NEC involves a complex interplay of factors that result in a deleterious immune response, injury to the intestinal mucosa, and in its most severe form, irreversible intestinal necrosis. Treatments for NEC remain limited, but one of the most effective preventative strategies for NEC is the provision of breast milk feeds. In this review, we discuss mechanisms by which bioactive nutrients in breast milk impact neonatal intestinal physiology and the development of NEC. We also review experimental models of NEC that have been used to study the role of breast milk components in disease pathophysiology. These models are necessary to accelerate mechanistic research and improve outcomes for neonates with NEC.

Enzymatic Hydrolysis of Tenebrio molitor (Mealworm) Using Nuruk Extract Concentrate and an Evaluation of Its Nutritional, Functional, and Sensory Properties

Enzymatic protein hydrolysis is a well-established method for improving the quality of dietary proteins, including edible insects. Finding effective enzymes from natural sources is becoming increasingly important. This study used nuruk extract concentrate (NEC), an enzyme-rich fermentation starter, to produce protein hydrolysate from defatted Tenebrio molitor (also called mealworm, MW). The nutritional, functional, and sensorial properties of the hydrolysate were then compared to those obtained using commercial proteases (alcalase and flavourzyme). The protease activities of the crude nuruk extract (CNE), NEC, alcalase, and flavourzyme were 6.78, 12.71, 11.07, and 12.45 units/mL, respectively. The degree of hydrolysis and yield of MW hydrolysis by NEC were 15.10 and 35.92% (w/w), respectively. MW hydrolysate was obtained using NEC and had a significantly higher free amino acid content (90.37 mg/g) than alcalase (53.01 mg/g) and flavourzyme (79.64 mg/g) hydrolysates. Furthermore, the NEC hydrolysis of MW increased the antioxidant and angiotensin-converting enzyme inhibitory activity, with IC₅₀ values of 3.07 and 0.15 mg/mL, respectively. The enzymatic hydrolysis also improved sensory properties, including umaminess, sweetness, and saltiness. Overall, this study found that the NEC hydrolysis of MW outperformed commercial proteases regarding nutritional quality, sensory attributes, and biological activity. Therefore, nuruk could potentially replace commercial proteases, lowering the cost of enzymatic protein hydrolysis.

Effects of Oral Collagen for Skin Anti-Aging: A Systematic Review and Meta-Analysis

This paper presents a systematic review and meta-analysis of 26 randomized controlled trials (RCTs) involving 1721 patients to assess the effects of hydrolyzed collagen (HC) supplementation on skin hydration and elasticity. The results showed that HC supplementation significantly improved skin hydration (test for overall effect: Z = 4.94, p < 0.00001) and elasticity (test for overall effect: Z = 4.49, p < 0.00001) compared to the placebo group. Subgroup analyses demonstrated that the effects of HC supplementation on skin hydration varied based on the source of collagen and the duration of supplementation. However, there were no significant differences in the effects of different sources (p = 0.21) of collagen or corresponding measurements (p = 0.06) on skin elasticity. The study also identified several biases in the included RCTs. Overall, the findings suggest that HC supplementation can have positive effects on skin health, but further large-scale randomized control trials are necessary to confirm these findings.

Enteral formula compared to Nissen-Fundoplication: Data from a retrospective analysis on tolerance, utility, applicability, and safeness in children with neurological diseases

Objectives and study

Approximately 46–90% of children with neurological disorders (NDs) suffer from gastrointestinal diseases, such as gastro-esophageal reflux disease (GERD), constipation, or malnutrition. Therefore, enteral feeding is often necessary to achieve nutritional requirements. The treatment of GERD could be based on pharmacological therapy, nutritional treatment (changing the type of formula), or surgical treatment (Nissen Fundoplication, NF). The aim of this study was to describe and compare resource consumption between NE based on different formulas and NF in patients with ND.

Methods

We performed a retrospective analysis on all children with neurological damage (age: 29 days−17 years) treated from January 2009 to January 2019 due to nutritional problems and food and/or gastrointestinal intolerances. For all patients, demographic and anthropometric characteristics, symptoms, type of nutrition (formula and enteral access), and number and type of outpatient or emergency room visits were collected. Patients with &lt;24 months of age at the closing of the database and with &lt;24 months of follow-up were excluded.

Results

Out of 376 children, 309 children (M: 158; median age: 4 IQR 1–10) were enrolled, among which, 65 patients (NF group M: 33; median age: 5.3 IQR 1.8–10.7) underwent NF. Vomit, GERD, and dysphagia were more represented in the NF group (p &lt; 0.05). Our analysis shows that the NF group seems to present a lower number of hospitalization and a lower number of visits for non-GI disorders, but a higher number of visits for GI disorders compared to non-NF. In the NF group, a higher prevalence of the use of amino-acid-based formula and free diet is observed, with a trend for the lower prevalence of casein-based or whey+casein-based formula (Fisher test p = 0.072). The median cost of a patient enrolled in the database is € 19,515 ± 540 ($ 20,742.32 ± 573.96) per year, with no significant difference between the two groups. Regarding formula, at baseline, 76 children consumed a free diet, 24 a casein-based formula, 139 a whey+casein-based formula, 46 a whey-based formula, and 24 an amino-acid-based formula.

Conclusions

In conclusion, compared to EN, NF may not improve the clinical aspect and related costs in children with NDs. Considering the psychological and QoL burden for patients, in a “step-up” strategy, EN could be proposed as an efficient alternative to NF.

Unlocking the bioactivity of meat proteins: Comparison of meat and meat hydrolysate via simulated gastrointestinal digestion

Understanding the functional attributes of meat proteins is crucial for determining their nutritional benefits. Depending on the form in which meat proteins are available, the digestive process can release peptides which are valuable for nutrition and may also possess bioactive properties, affecting physiology. Liquid chromatography - mass spectrometry (LC-MS) was used to quantitatively compare the molecular peptide features (representing non-redundant peptides), during the different stages of a simulated gastrointestinal digestion process of a minimally processed powdered meat and its enzymatically produced hydrolysate. Results from a principal component analysis (PCA) indicated that the hydrolysate did not undergo extensive additional digestion whereas the powdered meat was digested both at the gastric and in the intestinal phases. Bioactive peptide sequence prediction identified the meat hydrolysate but not the meat powder as the only source of exact and partial bioactive matches in the angiotensin-I converting enzyme and dipeptidyl peptidase IV inhibition categories. Also, a higher source of cryptides (encrypted bioactive peptides), indicated that meat hydrolysates are potentially a better substrate for the release of these enzyme inhibitory peptides. These observations thus suggest that pre-digestion of a complex food matrix such as meat, may enhance its bioavailability following oral consumption early in the digestion process. SIGNIFICANCE: This work highlights enzymatic hydrolysis of meat proteins prior to ingestion allows for potentially higher bioavailability of bioactive peptides that inhibit angiotensin-I converting enzyme and dipeptidyl peptidase IV, thus possibly aiding high blood pressure and type 2 diabetes management.

Alternative dietary protein sources to support healthy and active skeletal muscle aging

To mitigate the age-related decline in skeletal muscle quantity and quality, and the associated negative health outcomes, it has been proposed that dietary protein recommendations for older adults should be increased alongside an active lifestyle and/or structured exercise training. Concomitantly, there are growing environmental concerns associated with the production of animal-based dietary protein sources. The question therefore arises as to where this dietary protein required for meeting the protein demands of the rapidly aging global population should (or could) be obtained. Various non-animal-derived protein sources possess favorable sustainability credentials, though much less is known (compared with animal-derived proteins) about their ability to influence muscle anabolism. It is also likely that the anabolic potential of various alternative protein sources varies markedly, with the majority of options remaining to be investigated. The purpose of this review was to thoroughly assess the current evidence base for the utility of alternative protein sources (plants, fungi, insects, algae, and lab-grown "meat") to support muscle anabolism in (active) older adults. The solid existing data portfolio requires considerable expansion to encompass the strategic evaluation of the various types of dietary protein sources. Such data will ultimately be necessary to support desirable alterations and refinements in nutritional guidelines to support healthy and active aging, while concomitantly securing a sustainable food future.

Feeding pigs amino acids as protein-bound or in free form influences postprandial concentrations of amino acids, metabolites, and insulin

Dietary proteins need to be digested first while free amino acids (AAs) and small peptides are readily available for absorption and rapidly appear in the blood. The rapid postprandial appearance of dietary AA in the systemic circulation may result in inefficient AA utilisation for protein synthesis of peripheral tissues if other nutrients implicated in AA and protein metabolism are not available at the same time. The objective of this experiment was to compare the postprandial concentrations of plasma AA and other metabolites after the ingestion of a diet that provided AA either as proteins or as free AA and small peptides. Twenty-four male growing pigs (38.8 ± 2.67 kg) fitted with a jugular catheter were assigned to one of three diets that provided AA either in protein form (INT), free AA and small peptides (HYD), or as free AA (FAA). After an overnight fast and initial blood sampling, a small meal was given to each pig followed by serial blood collection for 360 min. Postprandial concentrations of plasma AA, glucose, insulin, and urea were then measured from the collected blood. Non-linear regression was used to summarise the postprandial plasma AA kinetics. Fasting concentrations of urea and some AA were higher (P < 0.05) while postprandial plasma insulin and glucose were lower (P < 0.01) for INT than for HYD and FAA. The area under the curve of plasma concentration after meal distribution was lower for INT for most AAs (P < 0.05), resulting in a flatter curve compared to HYD and FAA. This was the result of the slower appearance of dietary AA in the plasma when proteins are fed instead of free AA and small peptides. The flatter curve may also result from more AAs being metabolised by the intestine and liver when INT was fed. The metabolism of AA of the intestine and liver was higher for HYD than FAA. Providing AA as proteins or as free AA and small peptides affected the postprandial plasma kinetics of AA, urea, insulin, and glucose. Whether the flat kinetics when feeding proteins has a positive or negative effect on AA metabolism still needs to be explored.

Peripheral Amino Acid Appearance Is Lower Following Plant Protein Fibre Products, Compared to Whey Protein and Fibre Ingestion, in Healthy Older Adults despite Optimised Amino Acid Profile

Plant-based proteins are generally characterised by lower Indispensable Amino Acid (IAA) content, digestibility, and anabolic properties, compared to animal-based proteins. However, they are environmentally friendlier, and wider consumption is advocated. Older adults have higher dietary protein needs to prevent sarcopenia, a disease marked by an accelerated loss of muscle mass and function. Given the lower environmental footprint of plant-based proteins and the importance of optimising dietary protein quality among older adults, this paper aims to assess the net peripheral Amino Acid (AA) appearance after ingestion of three different plant protein and fibre (PPF) products, compared to whey protein with added fibre (WPF), in healthy older adults. In a randomised, single-blind, crossover design, nine healthy men and women aged ≥65 years consumed four test meals balanced in AA according to the FAO reference protein for humans, matched for leucine, to optimally stimulate muscle protein synthesis in older adults. A fasted blood sample was drawn at each visit before consuming the test meal, followed by postprandial arterialise blood sampling every 30 min for 3 h. The test meal was composed of a soup containing either WPF or PPF 1-3. The PPF blends comprised pea proteins with varying additional rice, pumpkin, soy, oat, and/or almond protein. PPF product ingestion resulted in a lower maximal increase of postprandial leucine concentration and the sum of branched-chain AA (BCAA) and IAA concentrations, compared to WPF, with no effect on their incremental area under the curve. Plasma methionine and cysteine, and to a lesser extent threonine, appearance were limited after consuming the PPF products, but not WPF. Despite equal leucine doses, the WPF induced greater postprandial insulin concentrations than the PPF products. In conclusion, the postprandial appearance of AA is highly dependent on the protein source in older adults, despite providing equivalent IAA levels and dietary fibre. Coupled with lower insulin concentrations, this could imply less anabolic potential. Further investigation is required to understand the applicability of plant-based proteins in healthy older adults.

Effect of preoperative predigested formula vs. polymeric formula on bowel function recovery after definitive surgery for small intestinal entero-atmospheric fistula in patients with chyme reinfusion

Purpose

The purpose of this study is to compare the effect of preoperative predigested formula vs. polymeric formula on bowel function recovery following definitive surgery (DS) for small intestinal enteroatmospheric fistula (EAF).

Methods

In this retrospective study, from January 2005 to December 2019, the patients with small intestinal EAF and receiving a DS were enrolled. During the preoperative treatment, each patient received enteral nutrition via nasojejunal feeding and chyme reinfusion. The enrolled subjects were classified into two groups, based on their formula type: polymeric formula and predigested formula. Then, propensity scores matching (PSM) was used to further divide these patients into PSM polymeric formula group or PSM predigested formula group. The clinical characteristics of the groups were analyzed.

Result

A total of 137 patients were finally enrolled, with 72 patients in the polymeric formula group and 65 patients in predigested formula group. The postoperative ileus was manifested in a total of 61 (44.5%) cases, with 27 (37.5%) in the polymeric formula group and 34 (52.3%) in the predigested formula group (P = 0.04). It was predicted that the polymeric formula could result in a reduction in postoperative ileus (OR = 0.47; 95% CI: 0.21–0.95; P = 0.04). After 1:1 PSM, there were 110 patients included. The postoperative ileus was observed in 47 patients, with 18 (32.7%) in the polymeric formula group and 29 (52.7%) in the predigested formula group (P = 0.03). After PSM, the polymeric formula demonstrated a reduction in the incidence of postoperative ileus (OR = 0.42; 95% CI: 0.19–0.92; P = 0.03).

Conclusion

Compared with predigested formula, the preoperative polymeric formula appears to be associated with earlier recovery of bowel function after DS for EAF.

Bioactive peptides in the pancreatin-hydrolysates of whey protein support cell proliferation and scavenge reactive oxygen species

Whey protein (WP) in milk shows physiologically active functions such as cholesterol control and immune system strengthening. In this study, we performed hydrolysis and peptide polarity fractionation to enhance the efficacy and diversity of its physiological activities, using the digesting enzyme, pancreatin. Our results indicate that hydrolysis significantly increased the cell proliferation of the WP fractions, with the lower-polarity fractions showing greater efficacy in this regard. Our results indicate that hydrolysis significantly increases cell proliferation of the WP fractions. Additionally, we confirmed differences in the antioxidant activity of the WP fractions as a function of polarity was confirmed via scavenging 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay in vitro. WP itself did not show anti-inflammatory efficacy. However, all the hydrolyzed fractions downregulated the mRNA expression levels of inflammatory cytokines in all treated cell lines and, based on a senescence-associated (SA)-β-galactosidase assay, the fraction with the lowest polarity (F6) inhibited cellular senescence to the greatest extent. Furthermore, we identified the peptide sequences with various physiological activities from whey protein hydrolysates through mass spectrometry. Taken together, our results indicate that the fractionation of WP via hydrolysis generates novel functions including promoting cellular cell proliferation, anti-inflammatory effects, and enhancing antioxidant and anti-cellular senescence.

Early Enteral Nutrition with High-Protein Whey Peptide Digestive Nutrients May Improve Prognosis in Subarachnoid Hemorrhage Patients

Background and Objectives: Nutritional management in patients with subarachnoid hemorrhage (SAH) during the acute phase is important; however, there is no proper evidence or recommendations on the appropriate nutrients for early enteral nutrition. This study compared the influence the two different tube-feeding liquid diets for early enteral nutrition might have on the prognosis of patients with SAH. Materials and Methods: In a seven-year period, this single-center retrospective study included 245 patients with aneurysmal SAH who underwent craniotomy and aneurysm neck clipping and received enteral nutrition. The patients were divided into two groups according to the nutrient received: (1) high-protein whey peptide oligomeric formula diet (oligomeric group, 109 patients); and (2) high eicosapentaenoic acid-containing polymeric formula diet (polymeric group, 136 patients). The modified Rankin Scale (mRS) score at discharge was evaluated as the primary outcome. The presence or absence of diarrhea (watery stool and mushy stool) during the period from initiation of enteral nutrition to discharge from the stroke unit was also evaluated. Results: There were no significant differences in patient characteristics between groups. The time until initiation of enteral feeding in the oligomeric and polymeric groups was 2.8 ± 2.3 and 2.9 ± 2.2 days, respectively. The proportion of patients with mRS scores of 0–1 was significantly higher in the oligomeric group (25.7%) than in the polymeric group (14.7%) (p = 0.036), while the incidence of watery stool was significantly lower in the oligomeric group (15.8% to 34.3% in the polymeric group) (p = 0.003). Multivariate analyses confirmed that the oligomeric diet and the presence or absence of diarrhea significantly affected the mRS scores. Conclusions: The adoption of early enteral nutrition with high-protein whey peptide digestive nutrients might be associated with superior mRS scores at discharge and decreased diarrhea in patients with SA, indicating that the choice of nutrients might affect the outcome and prognosis.

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).

Comparative Efficacy of Fish Meal Replacement With Enzymatically Treated Soybean Meal on Growth Performance, Immunity, Oxidative Capacity and Fecal Microbiota in Weaned Pigs

This study investigated the growth performance, immunity, antioxidant capacity and fecal microbiota of weaned pigs by partially or completely replacing dietary fish meal with enzymatically treated soybean meal. A total of 144 piglets (initial body weight of 7.19 ± 0.11 kg) weaned at 28 d were allotted to 3 dietary treatments (6 replicates per treatment): 4% fish meal diet (FM); 2% fishmeal plus 6% enzymatically treated soybean meal (ESBM1); and 6% enzymatically treated soybean meal without fish meal (ESBM2). The experimental period was 28 d, serum was collected at day 14 and day 28 for biochemical parameters analysis, feces was obtained for microbiota analysis at 28d. The body weight, average daily gain and average daily feed intake of piglets in the ESBM2 group were significantly increased compared with those in the FM and ESBM1 groups from 0 to 28 d, respectively (P < 0.05). The diets with enzymatically treated soybean meal in ESBM1 and ESBM2 groups decreased the diarrhea rate (P < 0.05). Compared with FM, ESBM1 and ESBM2 decreased 5-hydroxytryptamine (5-HT) (P < 0.05). ESBM1 decreased diamine oxidase (DAO) and Interleukin 6 (IL-6) compared with FM and ESBM2 (P < 0.05). ESBM1 decreased serum Interleukin 1β (IL-1β) compared with FM at d 14 (P < 0.05). The serum Immunoglobulin E (IgE), secretory curl associated protein 5 (sFRP-5) were higher in ESBM1 compared with FM and ESBM2 (P < 0.05). ESBM2 increased super oxidase dismutase (SOD) level and decreased malondialdehyde (MDA) content compared with FM and ESBM1, the concentration of SOD in ESBM1was higher than that in FM (P < 0.05). ESBM1 decreased cortisol and caspase 3 (Casp-3) (P < 0.05). FM showed a higher content of tri-iodothyronine (T3) (P < 0.05) and a lower thyroxine/ tri-iodothyronine ratio compared with those in the other two groups (P < 0.05). The concentration of leptin was lower in ESBM2 (P < 0.05). ESBM1 had a higher α-diversity than ESBM2 (P < 0.05). The microbiota composition was different among three treatments (difference between FM and ESBM1, p = 0.005; FM and ESBM2, p = 0.009; ESBM1 and ESBM2, p = 0.004). ESBM2 tend to increase the abundance of Firmicutes (P = 0.070) and decrease Bacteroidetes (P = 0.069). ESBM2 decreased the abundance of Parabacteroides and increased SMB53 compared with FM (P < 0.05). The spearman correlation analysis revealed that the abundance of Parabacteroides enriched in FM group was negatively correlated with SOD, Megasphaera enriched in ESBM2 group were positively correlated with SOD. The abundance of Lachnospira enriched in ESBM2 group were negatively correlated with serum concentration of D-lactate, DAO, IL-6, and NO. In conclusion, under the conditions of this study, diet with only ESBM demonstrate the beneficial impact on intestinal microbiota developments, antioxidant capacity as well as growth performance for weaned pigs.

Different dietary starch patterns in low-protein diets: effect on nitrogen efficiency, nutrient metabolism, and intestinal flora in growing pigs

Background

Protein releases amino acids faster than starch releases glucose in digestive tract of pigs fed low-protein (LP) diets. Poor synchronization of dietary glucose and amino acids supply leads to compromised nitrogen efficiency. Dietary starch patterns modulation may improve this situation.

Methods

Growing barrows (29.7 ± 2.0 kg) were randomly allotted into 5 dietary treatments with LP diets consisting of different purified starches. Treatments included: waxy corn starch (W LP), corn starch + waxy corn starch (C + W LP), corn starch (C LP), pea starch + waxy corn starch (P + W LP) and pea starch (P LP). In the experiment, growth performance, protein deposition, nutrient metabolism, and fecal microbial community of pigs were investigated. In vitro starch digestion was used for predicting the in vivo glucose response.

Results

Dietary starch in vitro glucose release profile was determined by starch source and the ratio of amylopectin and amylose. C + W LP treatment showed decreased total nitrogen excretion and plasma citrulline concentration and improved plasma leptin concentration among treatments (P < 0.05). Besides, the highest nitrogen apparent biological value, whole-body protein deposition and growth performance and lowest urinary nitrogen excretion were also observed in C + W LP treatment. Compared with the other groups, C + W LP and C LP showed increased plasma pyruvate, IGF-1, and lipase concentrations (P < 0.05). The W LP group presented dramatically increased plasma alanine and urea nitrogen concentration and decreased aldolase and leptin concentrations (P < 0.05). Dietary starch patterns did not make an impact on bacterial richness and diversity, but changed the taxonomic and functional structures of the microbial communities. Microbial protein fermentation product (isobutyrate and isovalerate) presented increased in P LP treatments compared with the other treatments (P < 0.05).

Conclusions

Dietary starch patterns modulation can regulate dietary glucose release profile, nutrient metabolism, protein turnover, and fecal microbial fermentation in pigs. The optimal dietary glucose release profile effectively strengthened whole-body protein deposition and improve nitrogen efficiency and growth performance in growing pigs fed LP diets.

Milk proteins: Processing, gastric coagulation, amino acid availability and muscle protein synthesis

It is well-known that the postprandial muscle protein synthetic response to protein ingestion is regulated on various levels, including dietary protein digestion and amino acid (AA) absorption, splanchnic AA retention, the availability of dietary protein-derived AA in the circulation, delivery of AA to the muscle, uptake of AA by the muscle, and intramuscular signaling. AA availability after consumption of dairy products is primarily determined by the rate of gastric emptying of milk proteins, which is mainly linked to coagulation of milk proteins in the stomach. Caseins form gastric coagula, which make their gastric emptying and subsequent postprandial aminoacidemia notably slower than that of whey proteins. Only recently, the role of processing, food structure, preservation and matrix on coagulation herein has been getting attention. In this review we describe various processes, that affect gastric coagulation of caseins and therewith control gastric emptying, such as the conversion to caseinate, heat treatment in the presence of whey proteins, conversion to stirred yoghurt and enzymatic hydrolysis. Modulating product characteristics by processing can be very useful to steer the gastric behavior of protein, and the subsequent digestion and AA absorption and muscle anabolic response to maintain or increase muscle mass.

The acute effects of insect vs. beef-derived protein on postprandial plasma aminoacidemia, appetite hormones, appetite sensations, and energy intake in healthy young men

BACKGROUND/OBJECTIVES

The purpose of this study was to evaluate the acute effects of ingesting beef- and insect-derived protein on postprandial plasma amino acid and appetite hormone concentrations, appetite sensations, and ad libitum energy intake.

SUBJECTS/METHODS

In a randomized, double-blind, crossover study, 20 young men (23 (SD: 4) y) completed two trials during which arterialized blood samples and VAS questionnaires were collected at baseline, and over 300-min after ingestion of beverages with similar energy and macronutrient content containing 25 g beef- or insect-derived (cricket) protein. Blood samples were analyzed for plasma amino acid and appetite hormone concentrations, while VAS questionnaires were applied to assess appetite sensations. After each trial, an ad libitum meal was immediately provided to assess energy intake.

RESULTS

Adjusted mean postprandial incremental area under the curve (iAUC) was greater for cricket vs. beef-derived protein for plasma leucine, branched-chain amino acid, and essential amino acid concentrations (all P < 0.0001). Adjusted mean postprandial iAUC for hunger was lower following beef (-3030 (SE: 860)) vs. cricket-derived (-1197 (SE: 525)) protein (Difference: -1833 (95% CI: -3358, -308); P = 0.02), but was not different for other appetite sensations or appetite hormones (all P > 0.05). Adjusted mean ad libitum energy intake was 4072 (SE: 292) and 4408 (SE: 316) kJ following beef- and cricket-derived protein (Difference: -336 (95% CI: -992, 320); P = 0.30).

CONCLUSION

Acute ingestion of cricket and beef-derived protein leads to differences in postprandial plasma amino acid concentrations, but elicits similar effects on appetite hormones, appetite sensations, and ad libitum energy intake in young men.

Plasma Amino Acid Appearance and Status of Appetite Following a Single Meal of Red Meat or a Plant-Based Meat Analog: A Randomized Crossover Clinical Trial

Background

Red meat is a nutrient-dense food and a dietary staple. A new generation of plant-based meat analogs (PBMAs) have been designed to mimic the experience of eating meat, but there is limited evidence about their digestive efficacy and nutritional quality.

Objectives

We compared the postprandial digestive response of a single meal containing meat commercially raised in New Zealand, including lamb, on-farm pasture-raised beef (Pasture), or grain-finished beef (Grain) with a PBMA (Beyond Burger; Beyond Meat) sold through consumer retail. The primary outcome was the appearance of amino acids in plasma. Secondary outcomes included glucose and insulin, appetite assessment, and anthropometry.

Methods

Thirty healthy men (20-34 y) participated in a double-blinded randomized crossover trial. Each consumed 1 of the 4 test meals on 4 occasions separated by a washout period of at least 1 wk, following an overnight fast. The meal was a burrito-style wrap containing meat or PBMAs, vegetables, salsa, and seasonings in a flour tortilla. The amount of Pasture, Grain, Lamb, or BB was 220 g raw (∼160 g cooked). Venous blood samples were collected over 4 h. Appetite and hunger status was scored with visual analog scales.

Results

Pre-meal amino acid concentrations in plasma did not differ by group (P > 0.9), although several nonessential amino acids differed strongly according to participant BMI. Postprandial amino acids peaked at 2-3 h in all groups. The BB meal produced significantly lower plasma concentrations of total, essential, branched-chain, and non-proteogenic amino acids than the Lamb, Pasture, or Grain meals, based on AUC. There were no significant differences between meal groups in scores for hunger, fullness, or cravings.

Conclusions

Red meat meals exhibited greater bioavailability of amino acids compared with the PBMA (BB). Pasture versus Grain origins of the beef had little influence on participants' responses. This trial was registered at ClinicalTrials.gov as NCT04545398.

Bioactive Peptides: From Basic Research to Clinical Trials and Commercialization

Chronic diseases, including metabolic diseases, have become a worldwide public health issue. Research regarding the use of bioactive peptides or protein hydrolysates derived from food, as the diet-based strategies for the prevention and mitigation of chronic diseases, has increased exponentially in the past decades. Numerous in vitro and in vivo studies report the efficacy and safety of food-derived bioactive peptides and protein hydrolysates as antihypertensive, anti-inflammatory, antidiabetic, and antioxidant agents. However, despite promising preclinical results, an inadequate understanding of their mechanisms of action and pharmacokinetics restrict their clinical translation. Commercialization of bioactive peptides can be further hindered due to scarce information regarding their efficacy, safety, bitter taste, as well as the lack of a cost-effective method of production. This review provides an overview of the current clinical evidence and challenges to commercial applications of food-derived bioactive peptides and protein hydrolysates for the prevention and alleviation of chronic diseases.

Perspective: Vegan Diets for Older Adults? A Perspective On the Potential Impact On Muscle Mass and Strength

Consumers are increasingly encouraged to consume more plant-based foods and lower their consumption of foods from animal origin. Concurrently, older adults are recommended to consume an adequate amount of high-quality dietary protein for the prevention of age-related muscle loss. In the current Perspective article, we discuss why it may not be preferred to consume a vegan diet at an older age. Our perspective is based on the proposed lower bioavailability and functionality of proteins in a vegan diet due to the matrix of the whole-food protein sources, the lower essential amino acid (EAA) content, and specific EAA deficiencies in proteins derived from plant-based foods. We propose that a vegan diet increases the risk of an inadequate protein intake at an older age and that current strategies to improve the anabolic properties of plant-based foods are not feasible for many older adults. We provide recommendations for further research to substantiate the remaining knowledge gaps regarding the consequences of a vegan diet on skeletal muscle mass and strength at an older age.

A complete workflow for discovering small bioactive peptides in foods by LC-MS/MS: A case study on almonds

Identification of bioactive peptides is an increasingly important target for food chemists, particularly in consideration of the widespread application of proteolytic enzymes in food processing. Because the characterization of small peptides by LC-MS/MS is challenging, we optimized a dimethyl labeling technique to facilitate small peptide identification, using almond proteins as a model. The method was validated by comparing the MS/MS spectra of standards and almond-derived peptides in their nonderivatized and derivatized forms. Signal enhancement of a₁ ions was proved to effectively aid in the full-length sequencing of small peptides. We further validated this method using two industrially-relevant protein-rich extracts from almond flour: 1737 medium-sized peptides (5-39 amino acids) and 843 small peptides (2-4 amino acids) were identified. The use of an online bioactive peptide database, complemented by the existing literature, allowed the discovery of 208 small bioactive peptides, whereas for medium-sized peptides, only one was reported being bioactive.

Feeding intact proteins, peptides, or free amino acids to monogastric farm animals

For terrestrial farm animals, intact protein sources like soybean meal have been the main ingredients providing the required amino acids (AA) to sustain life. However, in recent years, the availability of hydrolysed protein sources and free AA has led to the use of other forms of AA to feed farm animals. The advent of using these new forms is especially important to reduce the negative environmental impacts of animal production because these new forms allow reducing the dietary crude protein content and provide more digestible materials. However, the form in which dietary AA are provided can have an effect on the dynamics of nutrient availability for protein deposition and tissue growth including the efficiency of nutrient utilization. In this literature review, the use of different forms of AA in animal diets is explored, and their differences in digestion and absorption rates are focused on. These differences affect the postprandial plasma appearance of AA, which can have metabolic consequences, like greater insulin response when free AA or hydrolysates instead of intact proteins are fed, which can have a profound effect on metabolism and growth performance. Nevertheless, the use and application of the different AA forms in animal diets are important to achieve a more sustainable and efficient animal production system in the future, as they allow for a more precise diet formulation and reduced negative environmental impact. It is, therefore, important to differentiate the physiological and metabolic effects of different forms of AA to maximize their nutritional value in animal diets.

Solid-Phase Extraction Approaches for Improving Oligosaccharide and Small Peptide Identification with Liquid Chromatography-High-Resolution Mass Spectrometry: A Case Study on Proteolyzed Almond Extract

Reverse-phase solid-phase extraction (SPE) is regularly used for separating and purifying food-derived oligosaccharides and peptides prior to liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. However, the diversity in physicochemical properties of peptides may prevent the complete separation of the two types of analytes. Peptides present in the oligosaccharide fraction not only interfere with glycomics analysis but also escape peptidomics analysis. This work evaluated different SPE approaches for improving LC-MS/MS analysis of both oligosaccharides and peptides through testing on peptide standards and a food sample of commercial interest (proteolyzed almond extract). Compared with conventional reverse-phase SPE, mixed-mode SPE (reverse-phase/strong cation exchange) was more effective in retaining small/hydrophilic peptides and capturing them in the high-organic fraction and thus allowed the identification of more oligosaccharides and dipeptides in the proteolyzed almond extract, with satisfactory MS/MS confirmation. Overall, mixed-mode SPE emerged as the ideal method for simultaneously improving the identification of food-derived oligosaccharides and small peptides using LC-MS/MS analysis.

Cheese Ingestion Increases Muscle Protein Synthesis Rates Both at Rest and During Recovery from Exercise in Healthy, Young Males: A Randomized Parallel-group Trial

Background

Protein ingestion increases muscle protein synthesis rates. The food matrix in which protein is provided can strongly modulate the postprandial muscle protein synthetic response. So far, the muscle protein synthetic response to the ingestion of whole foods remains largely unexplored.

Objectives

To compare the impact of ingesting 30 g protein provided as milk protein or cheese on postprandial plasma amino acid concentrations and muscle protein synthesis rates at rest and during recovery from exercise in vivo in young males.

Methods

In this randomized, parallel-group intervention trial, 20 healthy males aged 18–35 y ingested 30 g protein provided as cheese or milk protein concentrate following a single-legged resistance-type exercise session consisting of 12 sets of leg press and leg extension exercises. Primed, continuous intravenous L-[ring-¹³C₆]-phenylalanine infusions were combined with the collection of blood and muscle tissue samples to assess postabsorptive and 4-h postprandial muscle protein synthesis rates at rest and during recovery from exercise. Data were analyzed using repeated measures Time × Group (× Leg) ANOVA.

Results

Plasma total amino acid concentrations increased after protein ingestion (Time: P < 0.001), with 38% higher peak concentrations following milk protein than cheese ingestion (Time × Group: P < 0.001). Muscle protein synthesis rates increased following both cheese and milk protein ingestion from 0.037 ± 0.014 to 0.055 ± 0.018%·h^–1 and 0.034 ± 0.008 to 0.056 ± 0.010%·h^–1 at rest and even more following exercise from 0.031 ± 0.010 to 0.067 ± 0.013%·h^–1 and 0.030 ± 0.008 to 0.063 ± 0.010%·h^–1, respectively (Time: all P < 0.05; Time × Leg: P = 0.002), with no differences between cheese and milk protein ingestion (Time × Group: both P > 0.05).

Conclusion

Cheese ingestion increases muscle protein synthesis rates both at rest and during recovery from exercise. The postprandial muscle protein synthetic response to the ingestion of cheese or milk protein does not differ when 30 g protein is ingested at rest or during recovery from exercise in healthy, young males.