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

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

Water-Soluble Coffee Melanoidins Inhibit Digestive Proteases.

Coffee is one of the most popular beverages around the world and its consumption contributes to the daily intake of dietary melanoidins. Despite the emerging physiological role of food melanoidins, their effect on digestive processes has not been studied so far. In this study, the activity of the gastrointestinal enzymes pepsin and trypsin was investigated in the presence of water-soluble coffee melanoidins. The gastric enzyme pepsin is only slightly affected, whereas the intestinal enzyme trypsin is severely inhibited by coffee melanoidins. The intestinal digestibility of casein was significantly inhibited by coffee melanoidins at a concentration achievable by regular coffee consumption. The inhibition of proteolytic enzymes by coffee melanoidins might decrease the nutritional value of dietary proteins.

Effects of Dietary Colostrum Basic Protein on Bone Growth and Calcium Absorption in Mice.

Colostrum basic protein (CBP) is a trace protein extracted from bovine colostrum. Previous studies have shown that CBP can promote bone cell differentiation and increase bone density. However, the mechanism by which CBP promotes bone activity remains unclear. This study investigated the mechanism of the effect of CBP on bone growth in mice following dietary supplementation of CBP at doses that included 0.015%, 0.15%, 1.5%, and 5%. Compared with mice fed a normal diet, feeding 5% CBP significantly enhanced bone rigidity and improved the microstructure of bone trabeculae. Five-percent CBP intake triggered significant positive regulation of calcium metabolism in the direction of bone calcium accumulation. The expression levels of paracellular calcium transport proteins CLDN2 and CLDN12 were upregulated nearly 1.5-fold by 5% CBP. We conclude that CBP promotes calcium absorption in mice by upregulating the expression of the calcium-transporting paracellular proteins CLND2 and CLND12, thereby increasing bone density and promoting bone growth. Overall, CBP contributes to bone growth by affecting calcium metabolism.

Novel dietary strategies to manage sarcopenia.

PURPOSE OF REVIEW: Sarcopenia is a wasting disease, mostly age-related in which muscle strength and mass decline, such as physical performance. With aging, both lower dietary protein intake and anabolic resistance lead to sarcopenia. Moreover, aging and sarcopenia display low-grade inflammation, which also worsen muscle condition. In this review, we focused on these two main targets to study dietary strategies. RECENT FINDINGS: The better understanding in mechanisms involved in sarcopenia helps building combined dietary approaches including physical activity that would slow the disease progression. New approaches include better understanding in the choice of quality proteins, their amount and schedule and the association with antioxidative nutrients. SUMMARY: First, anabolic resistance can be countered by increasing significantly protein intake. If increasing amount remains insufficient, the evenly delivery protein schedule provides interesting results on muscle strength. Quality of protein is also to consider for decreasing risk for sarcopenia, because varying sources of proteins appears relevant with increasing plant-based proteins ratio. Although new techniques have been developed, as plant-based proteins display a lower availability, we need to ensure an adapted overall amount of proteins. Finally, specific enrichment with leucine from whey protein remains the dietary combined approach most studied and studies on citrulline provide interesting results. As cofactor at the edge between anabolic and antioxidative properties, vitamin D supplementation is to recommend. Antioxidative dietary strategies include both fibers, vitamins, micronutrients and polyphenols from various sources for positive effects on physical performance. The ω 3 -polyunsaturated fatty acids also display positive modifications on body composition. Gut microbiota modifiers, such as prebiotics, are promising pathways to improve muscle mass and function and body composition in sarcopenic patients. Nutritional interventions could be enhanced by combination with physical activity on sarcopenia. In healthy older adults, promoting change in lifestyle to get near a Mediterranean diet could be one of the best options. In sarcopenia adults in which lifestyle changes appears unprobable, specific enrichement potentialized with physical activity will help in the struggle against sarcopenia. Longitudinal data are lacking, which makes it hard to draw strong conclusions. However, the effects of a physical activity combined with a set of nutrition interventions on sarcopenia seems promising.

Interactive effects of dietary protein and nano-chitosan on growth performance, immune response, and histological aspects of lymphoid organs in broiler chickens.

A feeding trial was conducted to assess the effect of partial replacement of dietary soybean meal by three plant protein sources: coconut, rocket seed, and black cumin meals with their combination in the presence or absence of nano-chitosan (NCH) on growth performance and immune response in broiler chickens. Five starter and grower diets were formulated and used from 1 to 42 days of age. The NCH was added to starter and grower diets at 1.0 g/kg. Five-hundred-fifty-day-old Arbor Acres Plus broiler chicks were randomly divided into ten treatments with five equal replications. Final body weight (FBW), body weight gain (BWG), feed intake (FI), feed conversion ratio (FCR), and blood plasma parameters were investigated. Histological aspects of lymphoid organs (thymus: T, bursa of Fabricius: B, and spleen: S) were characterized. Apart from added NCH, the FBW, BWG, and FCR of broilers fed the diets containing the tested plant proteins were significantly superior to the control ones. However, FI of birds fed the diets containing CM alone or combined with RSM plus BCM was significantly reduced. All experimental broilers displayed high plasma levels of IgG compared with the control group. There were significant increases in plasma concentrations of IgM, IgA, and T4 for groups that fed the diets containing RSM, BCM, and mixture of CM, RSM, and BCM compared with their controls. The T3 levels of broilers fed the tested plant proteins were significantly increased compared with the controls. Aside from plant protein source, broilers fed the NCH-enriched diets achieved significant increases in levels of IgM, TAC, and FSH and activities of CAT and SOD but reduced the MDA level compared with control. The interactions between plant protein source and added nano-chitosan were not interrelated. Furthermore, CM, RSM, and BCM can be used as complementary dietary proteins singly or combined with NCH with no adverse effects on growth performance. Addition of NCH molecules has a positive effect on live body weight and increases feed intake compared with control chicks.

The effect of sex and dietary crude protein level on nutrient transporter gene expression and cecal microbiota populations in broiler chickens.

It is well known that male and female broilers differ in their growth performance and that many physiological factors contribute to this difference. The aim of this experiment is to investigate if there are differences between male and female broilers in cecal microbiota and nutrient transporter gene expression and if these differences play a role in the growth performance of broilers. The possible effect of protein level and its interaction with sex on microbiota and expression of the nutrient transporters were also investigated. Samples were collected from male and female birds fed either standard crude protein (SCP) or reduced crude protein diets (RCP) at the age of d 35. The experiment was designed as a 2 × 2 factorial arrangement of treatments consisting of 448 Cobb 500 broilers assigned to 32-floor pens with 4 treatments, 8 replicates, and 14 birds per pen for performance measurements. The factors were sex (male or female) and dietary crude protein (CP) level (standard or reduced). Body weight gain (BWG), feed intake and feed conversion ratio were recorded for each pen. Sex had a significant effect on BWG and FCR (P < 0.001) where males had a significantly higher BWG and better FCR compared to females. There was a significant interaction between sex and protein level on feed intake (FI) (P < 0.05), where male birds had a higher FI compared to female birds only when the birds were fed SCP but not RCP diets. There was a significant interaction between CP level and sex on the expression of CAT2 (P = 0.02) and PEPT2 (P = 0.026) where the genes were significantly upregulated in females but only when the RCP diet was fed. The RCP diet upregulated the expression of BoAT (P = 0.03) as a main effect. Female birds had significantly higher expression of the PepT-2 gene compared to the males. The alpha diversity of the cecal microbiota showed differences among the treatments. The Shannon diversity index was statistically higher (P = 0.036) for males fed the SCP diet and the Chao1 index for evenness was statistically higher (P = 0.027) in females fed the SCP diet. There was also a difference in the relative abundance of the 15 most common genera found in the cecal content of the broilers in this experiment and lastly, the differential composition of microbiota between the different treatments was also significantly different. This study suggests that chickens are able to compensate for a reduction in AA substrates when fed a low CP diet through the upregulation of certain AA transporters, females may adapt to low CP diets better by such upregulation compared to males, and lastly, sex has an effect on the cecal microbial population and these differences contribute towards the performance differences between male and female broilers.

Using low-protein diet in egg production for win-win of productivity and environmental benefits should be prudent: Evidence from pilot test.

A shortage of feed protein resources restricts poultry productivity. Key strategies to alleviate this problem include improvements to the structure of the gut microbiota by the appropriate intake of high-quality protein, improvements to the comprehensive protein utilization rate, and reducing the consumption of protein raw materials. In addition, damage to the environment caused by nitrogen emissions needs to be reduced. The aim of the study was to evaluate the effects of dietary protein levels on laying performance, host metabolism, ovarian health, nitrogen emissions, and the gut microbial structure and function of laying hens. In total, 360 hens at the age of 38 weeks were randomly allotted four treatments. Each of the groups consisted of nine replicates, with 10 birds per replicate, used for 12 weeks of study. Dietary protein levels of the four groups were 13.85 %, 14.41 %, 15.63 %, and 16.30 %. Results revealed that, compared with the 13.85 % crude protein (CP) group, the 15.63 % CP group experienced significantly enhanced final body weight, average daily gain, egg production, and egg mass. Compared with the 16.30 % CP group, the other groups' serum concentrations of immunoglobulin G (IgG) and immunoglobulin M (IgM) were significantly reduced. Compared with the 16.30 % CP group, the 13.85 % and 15.63 % groups had increased CP utilization rates but reduced nitrogen emission rate, and daily per egg and per kilogram egg nitrogen emissions rose with increased dietary protein levels. Compared to the 13.85 % and 14.41 % CP groups, the 16.30 % CP group exhibited a significant increase in the expression of genes related to amino acids and carbohydrate metabolic pathways. According to the linear discriminant analysis effect size diagram, the predominant bacteria in the 15.63 % CP group (e.g., Subdoligranulum, and Ruminococcaceae_UCG-013) were significantly related to CP utilization. The results of this study emphasize that production performance is significantly reduced when protein levels are too low, whereas too high protein levels lead to gut microbiota imbalance and a reduction in the utilization efficiency of nutrients. Therefore, on the premise of ensuring the health of hens, the structure of the gut microbiota can be improved by appropriately reducing protein levels, which helps to balance the relationships among host health, productivity, resources, and the environment.

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).

Regression equation for predicting dietary phosphorus intake based on estimated dietary protein intake: A multicenter cross-sectional study in China.

BACKGROUND: Protein and phosphorus intake, which affect chronic kidney disease (CKD), is assessed using cumbersome food diaries. Therefore, more straightforward and accurate methods of assessing protein and phosphorus intake are needed. We decided to investigate the nutrition status and dietary protein and phosphorus intake of patients with stages 3, 4, 5, or 5D CKD. METHODS: This cross-sectional survey included outpatients with CKD at seven class A tertiary hospitals in Beijing, Shanghai, Sichuan, Shandong, Liaoning, and Guangdong in China. Protein and phosphorus intake levels were calculated using 3-day food records. Protein levels and calcium and phosphorus serum concentrations were measured; urinary urea nitrogen was determined using a 24-h urine test. Protein and phosphorus intakes were calculated using the Maroni and Boaz formulas, respectively. The calculated values were compared with the recorded dietary intakes. An equation that regressed phosphorus intake on protein intake was constructed. RESULTS: The average recorded energy and protein intake was 1637.5 ± 595.74 kcal/day and 56.97 ± 25.25 g/day, respectively. Overall, 68.8% of patients had a good nutrition status (grade A on the Subjective Global Assessment). The correlation coefficient between protein intake and calculated intake was 0.145 (P = 0.376) and that between phosphorus intake and calculated intake was 0.713 (P < 0.001). CONCLUSION: Protein and phosphorus intakes correlated linearly. Chinese patients with stage 3-5 CKD had low daily energy intake but high protein intake. Malnutrition was present in 31.2% of patients with CKD. The phosphorus intake could be estimated from the protein intake.

Oilseed meal proteins: From novel extraction methods to nanocarriers of bioactive compounds.

The global demand for animal proteins is predicted to increase twofold by 2050. This has led to growing environmental and health apprehensions, thereby prompting the appraisal of alternative protein sources. Oilseed meals present a promising alternative due to their abundance in global production and inherent dietary protein content. The alkaline extraction remains the preferred technique for protein extraction from oilseed meals in commercial processes. However, the combination of innovative techniques has proven to be more effective in the recovery and functional modification of oilseed meal proteins (OMPs), resulting in improved protein quality and reduced allergenicity and environmental hazards. This manuscript explores the extraction of valuable proteins from sustainable sources, specifically by-products from the oil processing industry, using emerging technologies. Chemical structure, nutritional value, and functional properties of the main OMPs are evaluated with a particular focus on their potential application as nanocarriers for bioactive compounds.

Beta-hydroxy-ß-methyl butyrate-supplemented diet for broiler chickens is more conducive to dietary protein reduction than a leucine-supplemented diet until 21 days old.

BACKGROUND: Dietary l-leucine or its metabolite 𝛽-hydroxy-𝛽-methylbutyrate (HMB) has a crucial role in the muscle protein metabolism of broilers during the first few-week growing period. The present study aimed to evaluate the effects of l-leucine (LLPD) or HMB (HLPD) supplementation in a low-protein diet (20%, LPD) until 21 days old on performance, carcass weight, muscle yield and meat quality, as well as intestinal morphometry, in broiler chickens. RESULTS: From days 1-42, LPD decreased body weight gain and feed intake (FI) and increased feed conversion ratio compared to a standard protein diet (22%, SPD). The LLPD and HLPD did not affect FI, but the LLPD decreased the body weight gain and increased the feed conversion ratio compared to the SPD. The LPD group had lower body and muscle weights than other groups. Compared to LPD, HLPD increased dressing percentage. The LPD decreased the serum insulin-like growth factor-1 content compared to the SPD and LLPD. The duodenal villus height of the LPD and LLPD broilers was smaller than those of the SPD and HLPD birds. The HLPD broilers had lower duodenal villus width than the SPD birds. The duodenal crypt depth and ileal mucosal thickness were higher in the HLPD group than in other groups. The HLPD and LLPD enhanced the ileal villus height compared to the SPD. The LLPD and HLPD treatments did not affect meat quality traits compared to the SPD treatment. CONCLUSION: Dietary HMB could be a conducive approach to reducing dietary protein for broilers until 21 days old. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Effects of rumen-encapsulated methionine and lysine supplementation and low dietary protein on nitrogen efficiency and lactation performance of dairy cows.

Low crude protein (CP) diets might be fed to dairy cows without affecting productivity if the balance of absorbed AA were improved, which would decrease the environmental effect of dairy farms. The aim of this study was to investigate the effects of supplementing ruminally protected Lys (RPL) and Met (RPM) at 2 levels of dietary CP on nutrient intake, milk production, milk composition, milk N efficiency (MNE), and plasma concentrations of AA in lactating Holstein cows and to evaluate these effects against the predictions of the new NASEM (2021) model. Fifteen multiparous cows were used in a replicated 3 × 3 Latin square design with 21-d periods. The 3 treatments were (1) a high-protein (HP) basal diet containing 16.4% CP (metabolizable protein [MP] balance of -130 g/d; 95% of target values), (2) a medium-protein diet containing 15% CP plus RPL (60 g/cow per day) and RPM (25 g/cow per day; MPLM; MP balance of -314 g/d; 87% of target values), and (3) a low-protein diet containing 13.6% CP plus RPL (60 g/cow per day) and RPM (25 g/cow per day; LPLM; MP balance of -479 g/d; 80% of target values). Dry matter intake was less for cows fed MPLM and LPLM diets compared with those fed the HP diet. Compared with the HP diet, the intake of CP, neutral detergent fiber, acid detergent fiber, and organic matter, but not starch, was lower for cows fed MPLM and LPLM diets. Milk production and composition were not affected by MPLM or LPLM diets relative to the HP diet. Milk urea N concentrations were reduced for the MPLM and LPLM diets compared with the HP diet, indicating that providing a low-protein diet supplemented with rumen-protected AA led to greater N efficiency. There was no significant effect of treatment on plasma AA concentrations except for proline, which significantly increased for the MPLM treatment compared with the other 2 treatments. Overall, the results supported the concept that milk performance might be maintained when feeding lactating dairy cows with low CP diets if the absorbed AA balance is maintained through RPL and RPM feeding. Further investigations are needed to evaluate responses over a longer time period with consideration of all AA rather than on the more aggregated MP and the ratio between Lys and Met.

Evaluation of modified dried vinasse as an alternative dietary protein source for broilers.

The increase in poultry production and the high cost of soybean led to the search for alternative protein sources. One of these sources is vinasse, a by-product of the baker's yeast industry. Modified dried vinasse (MDV) can be produced for use in poultry nutrition by making some improvements in vinasse. Therefore, the present study aimed to examine the effect of the usage of MDV in broiler diets. A total of 192 daily male Ross 308 chicks were randomly assigned to four groups. MDV was included at the levels of 0%, 2%, 4%, and 6% in the diets for 42-day trial. Linear significant improvements in the final weight, body weight gain, feed efficiency, and digestibility were seen with increasing MDV levels. The use of MDV caused a significant reduction in feed consumption. The relative weight percentages of abdominal fat and serum cholesterol concentration were reduced linearly with increases in MDV levels. MDV inclusion linearly decreased the malondialdehyde concentration, but increased 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity in breast meat significantly. The protein content in breast meat was increased with MDV. Cecal beneficial microorganisms and serum IgG levels were increased linearly with MDV. In conclusion, results suggested that MDV could be a feasible option for alternative protein sources for broilers.

L-Lysine supplementation affects dietary protein quality and growth and serum amino acid concentrations in rats.

Single amino acid (AA) supplementations in foods are increasing, however their potential nutritional and physiological impacts are not fully understood. This study examined the effects of L-lysine (Lys) supplementation on protein quality of diets, serum AA concentrations and associations between the ratio of supplemental Lys to dietary protein (X) with body weight gain (BWG) in Sprague-Dawley male rats. Rats were fed one of 10 diets containing either 7% or 20% casein and supplemented with 0% (Control), 1.5%, 3%, 6% Lys or 6% Lys + 3% L-arginine (Arg) (8 rats/diet group) for 1 week. Lys supplementation reduced the protein quality of the casein-based diets (p < 0.01). BWG was reduced by supplemental Lys when X > 0.18. Free Lys supplementation dose-dependently increased serum Lys levels (p < 0.01), while increased protein-bound Lys (1.4% vs 0.52%) had little effect on serum Lys (p > 0.05). In the 7% casein diets, ≥ 1.5% supplemental Lys reduced serum alanine, asparagine, glycine, isoleucine, leucine, serine, tyrosine, valine, carnitine, ornithine, and increased urea. Supplementation of ≥ 3% Lys additionally reduced tryptophan and increased histidine, methionine and α-aminoadipic acid (α-AAA) compared to the Control (p < 0.05). In the 20% casein diets, addition of ≥ 1.5% Lys reduced serum asparagine and threonine, and ≥ 3% Lys reduced leucine, proline, tryptophan, valine, and ornithine, and 6% Lys reduced carnitine, and increased histidine, methionine, and α-AAA. Overall, this study showed that free Lys supplementation in a Lys-sufficient diet reduced the protein quality of the diets and modified the serum concentrations of many amino acids. Excess free Lys intake adversely affected growth and utilization of nutrients due to AA imbalance or antagonism. Overall lower protein intake increases susceptibility to the adverse effects of Lys supplementation.

Nutritional programming in Nile tilapia (Oreochromis niloticus): Effect of low dietary protein on growth and the intestinal microbiome and transcriptome.

Nutritional programming is the idea that early nutrient contributions can influence organismal structure or function and is documented in a variety of vertebrates, yet studies in fish are largely lacking. Tilapia are an important foodfish, with global production having increased rapidly since the 1990s. They exhibit high disease-resistance and grow well on formulated feeds which makes them an ideal aquaculture species, however incorporating high quality proteins into feeds can be costly. As feed constitutes 50-70% of total production costs in aquaculture, reducing protein content could curb these costs and increase revenue. Thus, we examined the effects of feeding Nile tilapia (O. niloticus) fry a restricted protein diet for the first 7-21 days on growth, gut microbial flora, and the intestinal transcriptome. Fish were fed either a 25% restricted or 48% control crude protein starter (ST) diet for up to 21 days and then switched to a 25% or 38% control crude protein growout (GO) diet. Fish fed a 25% ST diet for 14 days followed by a 38% GO diet had significantly higher lengths and weights and better feed efficiency than fish fed the control 48% ST and 38% GO diet after 56 days of culture. Growth of fry on the 25% ST, 7-day/38% GO and the 25% ST,7-day/25% GO diets did not differ from the those fed the control protein diets, while fish fed the 25% ST diet for 21 days had significantly lower growth and survival rates. We observed no significant differences in either alpha or beta diversity of the gut microbial flora between diets, however species richness (Shannon Index) was higher in fry fed the 25% protein ST diet regardless of the GO diet. Similarly, fish fed the 25% ST diet for 14 days followed by the 38% GO diet had minimal changes to the intestinal transcriptome relative to fish fed the control 48% ST and 38% GO diet. However, those fed 25% ST and GO diets for the entire 56 days exhibited substantial differences in the gut transcriptome from other groups showing gene expression profiles characteristic of detrimental changes to gut physiology, protein metabolism and immune function. Results suggest protein restriction for up to 14 days early in development leads to enhanced growth and feed efficiency with minimal effects on gut microbes or intestinal function. Protein restriction beyond this period appears detrimental to fish growth and health as underscored by expression of disease related genes and higher mortality rates.

Microbial dietary protein metabolism regulates GLP-1 mediated intestinal transit.

Depletion of gut microbiota is associated with inefficient energy extraction and reduced production of short-chain fatty acids from dietary fibers, which regulates colonic proglucagon (Gcg) expression and small intestinal transit in mice. However, the mechanism by which the gut microbiota influences dietary protein metabolism and its corresponding effect on the host physiology is poorly understood. Enteropeptidase inhibitors block host protein digestion and reduce body weight gain in diet-induced obese rats and mice, and therefore they constitute a new class of drugs for targeting metabolic diseases. Enteroendocrine cells (EECs) are dispersed throughout the gut and possess the ability to sense dietary proteins and protein-derived metabolites. Despite this, it remains unclear if enteropeptidase inhibition affects EECs function. In this study, we fed conventional and antibiotic treated mice a western style diet (WSD) supplemented with an enteropeptidase inhibitor (WSD-ETPi), analyzed the expression of gut hormones along the length of the intestine, and measured small intestinal transit under different conditions. The ETPi-supplemented diet promoted higher Gcg expression in the colon and increased circulating Glucagon like peptide-1 (GLP-1) levels, but only in the microbiota-depleted mice. The increase in GLP-1 levels resulted in slower small intestinal transit, which was subsequently reversed by administration of GLP-1 receptor antagonist. Interestingly, small intestinal transit was normalized when an amino acid-derived microbial metabolite, p-cresol, was supplemented along with WSD-ETPi diet, primarily attributed to the reduction of colonic Gcg expression. Collectively, our data suggest that microbial dietary protein metabolism plays an important role in host physiology by regulating GLP-1-mediated intestinal transit.

Effects of dietary protein content and crystalline amino acid supplementation patterns in low protein diets on intestinal bacteria and their metabolites in weaned pigs raised under Different sanitary conditions.

The objective of this experiment was to investigate the effects of dietary crude protein (CP) content and crystalline amino acids (CAA) supplementation patterns in low CP (LCP) diets on intestinal bacteria and their metabolites in weaned pigs raised under clean (CSC) or unclean sanitary conditions (USC). One hundred forty-four piglets (6.35 ±â€…0.63 kg) were assigned to one of six treatments in a 3 × 2 factorial arrangement based on CP content and sanitary conditions in a randomized complete block design to give eight replicates with three pigs per pen over a 21-d period. Diets consisted of a high CP (HCP; 21%) and two LCP (18%) diets supplemented with 9 CAA (Lys, Met, Thr, Trp, Val, Ile, Leu, His, and Phe) or only six CAA (Lys, Met, Thr, Trp, Val, and Ile) to meet the requirements. The CSC room was washed weekly, whereas the USC room had sow manure spread in the pens from the beginning of the study and was not washed throughout the experiment. Jejunum and colon digesta were sampled on day 21. Both jejunum and colon digesta were analyzed for ammonia nitrogen, short-chain fatty acids, and biogenic amines but only colon digesta was analyzed for microbiome composition (16s rRNA sequencing on MiSeq). Data were analyzed using R software for 16S rRNA and the MIXED procedure of SAS for microbial metabolites. Sanitation, CP content, and CAA supplementation patterns did not affect the diversity of colonic bacterial composition in weaned pigs. Pigs raised under USC had greater (P < 0.05) jejunal ammonia nitrogen concentration than those raised under CSC. Pigs fed LCP diets had reduced (P < 0.05) jejunal ammonia nitrogen concentration compared to those fed the HCP diet. Interactions between sanitation and dietary CP content were observed (P < 0.05) for: (1) jejunal acetate and (2) colonic spermidine and spermine, whereby (1) acetate concentrations decreased from NCP to LCP in pigs raised under the CSC but those concentrations increased under the USC, and (2) spermidine and spermine concentrations increased in LCP diets compared to HCP diet under USC, unlike CSC which did not show any difference between HCP and LCP. In conclusion, reducing dietary CP lowered ammonia nitrogen content regardless of sanitation and increased microbial metabolites in weaned pigs raised under USC. However, LCP diets with different CAA supplementation patterns did not affect bacterial diversity in weaned pigs, regardless of the hygienic conditions where the animals were housed.

Lowering dietary crude protein concentration by 3% to 4% units has been used as one of the strategies to promote growth and improve the gut health of weaned pigs. Undigested and endogenous protein could be available for microbial fermentation, and protein fermentation is considered detrimental to the gut health of the host animal. The unclean sanitary condition model mimics commercial raising conditions and stimulates a low-grade inflammatory and immune response. Ammonia nitrogen is one of the harmful metabolites derived by protein fermentation and pigs fed low-protein diets had decreased ammonia nitrogen than those fed high-protein diets. Also, pigs raised under unclean sanitation had greater ammonia nitrogen than those raised under clean sanitation. However, sanitation, protein content, and crystalline amino acids supplementation patterns did not affect the diversity of colonic bacterial composition in weaned pigs. The results obtained from the present study showed that a low protein diet could be used to improve gut health in weaned pigs.

Growth performance, hematology parameters and Aeromonas hydrophila challenge of pirarucu (Arapaima gigas) in response to dietary protein levels.

The pirarucu (Arapaima gigas) is a fast-growing Amazonian species of high commercial value. The present study aimed to determine the dietary crude protein (CP) level to promote maximum zootechnical performance for pirarucu fingerlings and as their resistance to Aeromonas hydrophila, as well as evaluate their hematological parameters. Pirarucu fingerlings (2.4 ± 0.08 g, 6.8 ± 0.52 cm) were distributed in 18 tanks (140 L, 40 fish per tank, n = 3) and fed six experimental diets consisting of increasing levels of CP: 300, 400, 450, 500, 550 and 650 g kg-1 in a completely randomized design. Data were submitted to one-way ANOVA (p < 0.05) and the ideal CP level for weight gain was determined using polynomial regression analysis. The dietary CP levels were evaluated using a quadratic polynomial regression and the level of 595 g kg-1 was determined for the best weight gain. The hematocrit of fish fed 300 g kg-1 was higher than in the other groups. No mortalities were observed after the 15-day bacterial challenge; however, number of pirarucu with bacterial damage on the pirarucu caudal fin was higher in the group that was fed the diet with 300 g kg-1. A dietary protein level of 618 g kg-1 is therefore recommended for providing maximum weight gain and immunological resistance in pirarucu fingerlings weighing 2.4-112.5 g.

Low-protein diet supplemented with inulin lowers protein-bound toxin levels in patients with stage 3b-5 chronic kidney disease: a randomized controlled study.

Introduction: Objective: this study aimed to evaluate whether low-salt low-protein diet (LPD) supplemented with 10 g of inulin could lower serum toxin levels in patients with chronic kidney disease (CKD), thereby providing evidence for adjusting dietary prescriptions of inhospital patients and outpatient nutrition consultants. Methods: we randomized 54 patients with CKD into two groups. Dietary protein intake compliance was evaluated using a 3-day dietary diary and 24-h urine nitrogen levels. The primary outcomes were indoxyl sulfate (IS) and p-cresyl sulfate (PCS), and secondary outcomes included inflammation marker levels, nutritional status, and renal function. We assessed 89 patients for eligibility, and a total of 45 patients completed the study, including 23 and 22 in the inulin-added and control groups, respectively. Results: PCS values decreased in both groups after intervention: inulin-added group, ∆PCS -1.33 (-4.88, -0.63) µg/mL vs. LPD group, -4.7 (-3.78, 3.69) µg/mL (p = 0.058). PCS values reduced from 7.52 to 4.02 µg/mL (p < 0.001) in the inulin-added group (p < 0.001). Moreover, IS decreased from 3.42 (2.53, 6.01) µg/mL to 2.83 (1.67, 4.74) µg/mL after adding inulin; ∆IS was -0.64 (-1.48, 0.00) µg/mL, and a significant difference was observed compared with the control group (p = 0.004). The inflammation index decreased after intervention. Conclusion: dietary fiber supplementation may reduce serum IS and PCS levels and modulate their inflammatory status in predialysis CKD patients.

Introducción: Objetivo: este ensayo aleatorizado doble ciego comparó el efecto de una dieta baja en proteínas (LPD) con o sin suplementos orales de 10 g de inulina en los niveles de PBUT en pacientes con ERC en prediálisis durante 12 semanas. Métodos: clasificamos aleatoriamente a 54 pacientes con ERC en dos grupos. El cumplimiento de la ingesta dietética de proteínas se evaluó utilizando un diario dietético de 3 días y nitrógeno en orina de 24 horas. Los resultados primarios fueron IS y PCS y los resultados secundarios incluyeron niveles de marcadores de inflamación, estado nutricional y función renal. Evaluamos la elegibilidad de 89 pacientes y 45 completaron la intervención, incluidos 23 y 22 en los grupos de inulina añadida y de control, respectivamente. Resultados: el sodio urinario promedio de 24 horas fue de 86 mmol/día y la ingesta promedio de proteínas fue de ~0,7 g/kg/día. Los valores de PCS exhibieron una tendencia decreciente en ambos grupos después de la intervención: grupo con inulina añadida, ∆PCS -1.33 (-4.88, -0.63) µg/mL vs. grupo LPD, -4.7 (-3.78, 3.69) µg/mL) (p =0,058). Los valores de PCS se redujeron de 7,52 a 4,02 µg/mL (p < 0,001) con inulina (p < 0,001). Además, IS disminuyó de 3,42 (2,53, 6,01) µg/mL a 2,83 (1,67, 4,74) µg/mL después de agregar inulina; El ∆IS fue -0,64 (-1,48; 0,00) µg/mL y se observó una diferencia significativa en comparación con el grupo control (p =0,004). Conclusión: la suplementación con fibra dietética puede reducir las toxinas de unión a proteínas séricas en pacientes con ERC en prediálisis y modular su estado inflamatorio.

Impact of Dietary Protein on the Management of Pediatric Short Bowel Syndrome.

Essential amino acids (AAs) play a key role in stimulating intestinal adaptation after massive small gut resection. The nutritional effect of dietary amino acids during intestinal regrowth has received considerable attention in recent years. This review explores the significance of dietary amino acids in the nutritional management of infants and children with intestinal failure and short bowel syndrome (SBS) as reported in the medical literature over the last three decades. A literature search was conducted using electronic databases. Breast milk emerged as the first-line enteral regimen recommended for infants with SBS. Hydrolyzed formulas (HFs) or amino acid formulas (AAFs) are recommended when breast milk is not available or if the infant cannot tolerate whole protein milk. The superiority of AAFs over HFs has never been demonstrated. Although glutamine (GLN) is the main fuel for enterocytes, GLN supplementation in infants with SBS showed no difference in the child's dependence upon parenteral nutrition (PN). Circulating citrulline is considered a major determinant of survival and nutritional prognosis of SBS patients. Early enteral nutrition and dietary supplementation of AAs following bowel resection in children are essential for the development of intestinal adaptation, thereby eliminating the need for PN.