Re-print of "Intestinal luminal nitrogen metabolism: role of the gut microbiota and consequences for the host"

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.

Amino Acids during Pregnancy and Offspring Cardiovascular-Kidney-Metabolic Health

Amino acids are essential for normal pregnancy and fetal development. Disruptions in maternal amino acid metabolism have been associated with various adult diseases later in life, a phenomenon referred to as the developmental origins of health and disease (DOHaD). In this review, we examine the recent evidence highlighting the significant impact of amino acids on fetal programming, their influence on the modulation of gut microbiota, and their repercussions on offspring outcomes, particularly in the context of cardiovascular-kidney-metabolic (CKM) syndrome. Furthermore, we delve into experimental studies that have unveiled the protective effects of therapies targeting amino acids. These interventions have demonstrated the potential to reprogram traits associated with CKM in offspring. The discussion encompasses the challenges of translating the findings from animal studies to clinical applications, emphasizing the complexity of this process. Additionally, we propose potential solutions to overcome these challenges. Ultimately, as we move forward, future research endeavors should aim to pinpoint the most effective amino-acid-targeted therapies, determining the optimal dosage and mode of administration. This exploration is essential for maximizing the reprogramming effects, ultimately contributing to the enhancement of cardiovascular-kidney-metabolic health in offspring.

Modeling Dynamics of Human Gut Microbiota Derived from Gluten Metabolism: Obtention, Maintenance and Characterization of Complex Microbial Communities

Western diets are rich in gluten-containing products, which are frequently poorly digested. The human large intestine harbors microorganisms able to metabolize undigested gluten fragments that have escaped digestion by human enzymatic activities. The aim of this work was obtaining and culturing complex human gut microbial communities derived from gluten metabolism to model the dynamics of healthy human large intestine microbiota associated with different gluten forms. For this purpose, stool samples from six healthy volunteers were inoculated in media containing predigested gluten or predigested gluten plus non-digested gluten. Passages were carried out every 24 h for 15 days in the same medium and community composition along time was studied via V3-V4 16S rDNA sequencing. Diverse microbial communities were successfully obtained. Moreover, communities were shown to be maintained in culture with stable composition for 14 days. Under non-digested gluten presence, communities were enriched in members of Bacillota, such as Lachnospiraceae, Clostridiaceae, Streptococcaceae, Peptoniphilaceae, Selenomonadaceae or Erysipelotrichaceae, and members of Actinomycetota, such as Bifidobacteriaceae and Eggerthellaceae. Contrarily, communities exposed to digested gluten were enriched in Pseudomonadota. Hence, this study shows a method for culture and stable maintenance of gut communities derived from gluten metabolism. This method enables the analysis of microbial metabolism of gluten in the gut from a community perspective.

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.

Next-generation prebiotics: Maillard-conjugates of 2'-fucosyllactose and lactoferrin hydrolysates beneficially modulate gut microbiome composition and health promoting activity in a murine model

Current prebiotics are predominantly carbohydrates. However, great competition exists among gut microbes for the scarce protein in the colon, as most consumed protein is digested and absorbed in the small intestine. Herein we evaluated in-vivo novel next-generation prebiotics: protein-containing-prebiotics, for selectively-targeted delivery of protein to colonic probiotics, to boost their growth. This system is based on micellar-particles, composed of Maillard-glycoconjugates of 2'-Fucosyllactose (2'-FL, human-milk-oligosaccharide) shell, engulfing lactoferrin peptic-then-tryptic hydrolysate (LFH) core. This core-shell structure lowers protein-core digestibility, while the prebiotic glycans are hypothesized to serve as molecular-recognition ligands for selectively targeting probiotics. To study the efficacy of this novel prebiotic, we fed C57BL/6JRccHsd mice with either 2'-FL-LFH Maillard-glycoconjugates, unconjugated components (control), or saline (blank). Administration of 2'-FL-LFH significantly increased the levels of short-chain-fatty-acids (SCFAs)-producing bacterial families (Ruminococcaceae, Lachnospiraceae) and genus (Odoribacter) and the production of the health-related metabolites, SCFAs, compared to the unconjugated components and to saline. The SCFAs-producing genus Prevotella significantly increased upon 2'-FL-LFH consumption, compared to only moderate increase in the unconjugated components. Interestingly, the plasma-levels of inflammation-inducing lipopolysaccharides (LPS), which indicate increased gut-permeability, were significantly lower in the 2'-FL-LFH group compared to the unconjugated-components and the saline groups. We found that Maillard-glycoconjugates of 2'-FL-LFH can serve as novel protein-containing prebiotics, beneficially modulating gut microbial composition and its metabolic activity, thereby contributing to host health more effectively than the conventional carbohydrate-only prebiotics.

Values for the Digestibility of Pea Protein Isolate or Casein Amino Acids Determined using the Dual Isotope Method Are Not Similar to Those Derived with the Standard Ileal Balance Method in Healthy Volunteers

BACKGROUND

The measurement of ileal amino acid (AA) digestibility is invasive and inappropriate when applied to vulnerable populations. The dual isotope method has been developed over the past 5 y as an alternative method.

OBJECTIVE

The aim of this work was to compare the indispensable amino acid (IAA) digestibility values of 2 different proteins obtained using the dual isotope and the standard ileal balance methods in the same subjects.

METHODS

Fifteen healthy adults completed the study. Over 4 h, they ingested 9 successive portions of mashed potatoes containing the test protein (pea protein or casein) labeled intrinsically with 15N and 2H, and a 13C-free AA mixture as a reference for the dual isotope method. Plasma was sampled regularly over the 8-h postprandial period, whereas the ileal digesta was collected continuously via a naso-ileal tube. Isotopic enrichments (15N and 13C) were measured in the digesta for the direct determination of ileal IAA digestibility, whereas plasma enrichments (2H and 13C) were measured to determine IAA digestibility using the dual isotope method.

RESULTS

The 4-h repeated meal procedure enabled the almost complete digestion of test proteins at 8 h and the attainment of a plasma isotopic plateau between 2.5 and 4 h. These conditions were necessary to perform the ileal balance and dual isotope methods simultaneously. For pea protein, the mean IAA digestibility was similar between the 2 methods, but significant differences (from 10% to 20%) were observed for individual IAA values. For casein, IAA digestibility was significantly lower with the dual isotope method for all the IAA analyzed.

CONCLUSIONS

Under our experimental conditions, the degree of agreement between the dual isotope and ileal balance methods varied among AAs and depended on the protein source. Further research is needed to validate the dual isotope method. This study was registered at clinicaltrials.gov as NCT04072770.

Effects of dietary protein level on intestinal function and inflammation in nursery pigs

High crude protein (CP; 21% to 26%) diets fed during the first 21 to 28 d postweaning are viewed negatively because of a perceived increase in the incidence rates of diarrhea due to increased intestinal protein fermentation and/or augmented enteric pathogen burden. This is thought to antagonize nursery pig health and growth performance. Therefore, our objective was to evaluate the impact of low vs. high dietary CP on 21-day postweaned pig intestinal function. Analyzed parameters included ex vivo intestinal barrier integrity (ileum and colon), ileal nutrient transport, tissue inflammation, and fecal DM. One hundred and twenty gilts and barrows (average body weight) were randomly assigned to one of two diets postweaning. Diets were fed for 21 d, in two phases. Phase 1 diets: low CP (17%) with a 1.4% standardized ileal digestible (SID) Lys (LCP), or high CP (24%) with a 1.4% SID Lysine (HCP). Phase 2: LCP (17%) and a 1.35% SID lysine, or HCP (24%) formulated to a 1.35% SID lysine. Pig growth rates, feed intakes, and fecal consistency did not differ (P > 0.05) due to dietary treatment. Six animals per treatment were euthanized for additional analyses. There were no differences in colonic epithelial barrier function as measured by transepithelial electrical resistance (TER) and fluorescein isothiocyanate (FITC)-dextran transport between treatments (P > 0.05). Interleukins (IL)-1α, IL-1β, IL-1ra, IL-2 IL-4, IL-6, and IL-12 were not different between treatments (P > 0.05). However, IL-8 and IL-18 were higher in HCP- vs. LCP-fed pigs (P < 0.05). There were no differences in fecal dry matter (DM; P > 0.05) between treatments. In the ileum, there was a tendency (P = 0.06) for TER to be higher in HCP-fed pigs, suggesting a more robust barrier. Interestingly, glucose and glutamine transport were decreased in HCP- vs. LCP-fed pigs (P < 0.05). FITC-dextran transport was not different between treatments (P > 0.05). There were also no differences in ileal cytokine concentrations between diets (P > 0.05). Taken together, the data show that low CP does not negatively impact colonic barrier function, fecal DM, or inflammation. In contrast, ileal barrier function and nutrient transport were altered, suggesting a regional effect of diet on overall intestinal function.

Standardisation of the C:N ratio in ileal digesta changes relationships among fermentation end-products during in vitro hindgut fermentation in pigs

Undigested proteins that become available for the microbiota in the hindgut can be used as building blocks for bacterial cells, or can enter various catabolic pathways. Degradation via protein fermentation pathways is least preferred, as several fermentation end-products released can be toxic for the host. Directing microbial protein metabolism towards protein synthesis or degradative pathways that result in less toxic end-products, for example through nutritional interventions, is an interesting strategy for improving health. We studied variation in protein fermentation patterns, resulting from variation in substrate composition. Ileal digesta, obtained from cannulated pigs fed different protein sources, were subjected to fermentation in vitro under different conditions; (1) ileal digesta were fermented as-is, (2) ileal digesta were fermented after standardisation to a constant high C:N ratio, by addition of high fermentable carbohydrates and (3) ileal digesta samples were incubated under limiting N concentrations. Gas production was monitored as an indirect measure of microbial activity, and fermentation end-products at different points in time were analysed by gas chromatography and high resolution mass spectrometry. Using principal component analysis, we identified patterns in protein fermentation end-products and related them to the composition of ileal digesta. Protein-associated fermentation end-product concentrations of e.g. isovaleric-, isobutyric-, phenylacetic acid and p-cresol were negatively affected by the available amount of high fermentable carbohydrates combined with a high C:N ratio. The aforementioned fermentation end-products positively correlated with NH3 concentrations and negatively with short-chain fatty acid (SCFA) concentrations. Standardisation to a constant high C:N ratio changed their relationship; isovaleric-, isobutyric-, phenylacetic acid and p-cresol lost their correlation with NH3 concentrations, became positively correlated with SCFA concentrations, and now showed a positive correlation with available amounts of high fermentable carbohydrates. Our observations demonstrate an important role of the C:N ratio in the relationship between fermentation end-products. At constant C:N, protein fermentation end-products correlate with end-products of carbohydrate fermentation and NH3, often considered as a proxy for protein fermentation, loses its predictive power.

Comparative analysis of gut bacteria of silkworm Bombyx mori L. on exposure to temperature through 16S rRNA high throughput metagenomic sequencing

Global warming is one of the serious threats that adversely affects the development and reproduction of silkworms. The ideal temperature for silkworms to carryout normal life activities is 20-30 °C. Certain bivoltine silkworms that are raised in tropical regions are thermotolerant. But, prolonged exposure to high temperatures may be fatal. In the present study, fifth instar larvae of bivoltine silkworm were exposed to heat shock at 40 ± 2 °C for a short period of one hour per day to examine the changes in the gut microflora. The study used high throughput sequencing to evaluate the impact of intestinal microbes of silkworms in response to high temperature. The findings demonstrated that elevated temperature has a negative impact on the intestinal microbes of silkworm compared to the control which were reared under the optimum temperature (25 ± 3° C). Four hundred and fifty eight (458) species of microbes were reported in the control group whereas only 434 species were reported in the temperature exposed group. The digestive process of silkworms may also be impaired by heat shock due to their effect on digestive enzymes. So, the results indicated that heat shock has an impact on the intestinal microflora of silkworms that control the activity of associated digestive enzymes which affects the digestion and nutritional intake, eventually impacting the growth and development of silkworm larvae and cocoons produced. The morphometric parameters of silkworm larvae and cocoons also showed a considerable drop when exposed to heat shock.

Harnessing actinobacteria potential for cancer prevention and treatment

Actinobacteria are gram-positive bacteria with high G:C ratio in their genetic makeup. They have been noted and studied for their capacity to produce bioactive substances with a range of uses in human health, and they also exhibit a unique property of adapting to extreme environments quite well. Actinobacteria may play an essential role in cancer prevention and treatment due to their synthesis of anticancer compounds, as indicated by recent studies. The aim of this review is to give a summary of what is currently known about the connection between actinobacteria and different types of cancer. This paper delineates the diverse array of actinobacterial bioactive compounds possessing anticancer properties, elucidates their mechanisms of action and explores potential applications in cancer treatment. Furthermore, this review highlights how the microbiome influences the onset and progression of cancer, as well as the discussing the potential benefits that actinobacteria may bring in terms of controlling the microbiome and contributing to the regulation of the tumour microenvironment to cure or prevent cancer.

Chinese Herbal Extracts Mitigate Ammonia Generation in the Cecum of Laying Hens: An In Vitro Study

The objectives of the study were to screen one or several Chinese herbal extracts with good ammonia emission reduction effects using an in vitro gas production study. The study consisted of a control (without Chinese herbal extract), and 11 experimental groups with added cinnamon extract (CE), Osmanthus extract (OE), tangerine peel extract (TPE), dandelion extract (DE), Coptis chinensis extract (CCE), honeysuckle extract (HE), Pulsatilla root extract (PRE), yucca extract (YE), licorice extract (LE), Ginkgo biloba extract (GBE), or astragalus extract (AE). The results showed that HE, PRE, YE, LE, GBE, and AE significantly reduced ammonia production (p ≤ 0.05). The most significant ammonia inhibition was achieved via AE, resulting in a 26.76% reduction. In all treatments, Chinese herbal extracts had no significant effect on pH, conductivity, or uric acid, urea, and nitrate-nitrogen concentrations (p > 0.05). However, AE significantly reduced urease activity and the relative activity of uricase (p ≤ 0.05). AE significantly increased the relative abundance of Bacteroides and decreased the relative abundance of Clostridium, Desulfovibrio, and Prevotell (p ≤ 0.05). Astragalus extract inhibited ammonia emission from laying hens by changing the gut microbial community structure, reducing the relative abundance of ammonia-producing bacteria, and reducing microorganisms' uricase and urease activities.

Recent Advances in Microbiota-Associated Metabolites in Heart Failure

Heart failure is a risk factor for adverse events such as sudden cardiac arrest, liver and kidney failure and death. The gut microbiota and its metabolites are directly linked to the pathogenesis of heart failure. As emerging studies have increased in the literature on the role of specific gut microbiota metabolites in heart failure development, this review highlights and summarizes the current evidence and underlying mechanisms associated with the pathogenesis of heart failure. We found that gut microbiota-derived metabolites such as short chain fatty acids, bile acids, branched-chain amino acids, tryptophan and indole derivatives as well as trimethylamine-derived metabolite, trimethylamine N-oxide, play critical roles in promoting heart failure through various mechanisms. Mainly, they modulate complex signaling pathways such as nuclear factor kappa-light-chain-enhancer of activated B cells, Bcl-2 interacting protein 3, NLR Family Pyrin Domain Containing inflammasome, and Protein kinase RNA-like endoplasmic reticulum kinase. We have also highlighted the beneficial role of other gut metabolites in heart failure and other cardiovascular and metabolic diseases.

Role of the gut microbiota in nutrient competition and protection against intestinal pathogen colonization

The human gut microbiota can restrict the growth of pathogens to prevent them from colonizing the intestine ('colonization resistance'). However, antibiotic treatment can kill members of the gut microbiota ('gut commensals') and reduce competition for nutrients, making these nutrients available to support the growth of pathogens. This disturbance can lead to the growth and expansion of pathogens within the intestine (including antibiotic-resistant pathogens), where these pathogens can exploit the absence of competitors and the nutrient-enriched gut environment. In this review, we discuss nutrient competition between the gut microbiota and pathogens. We also provide an overview of how nutrient competition can be harnessed to support the design of next-generation microbiome therapeutics to restrict the growth of pathogens and prevent the development of invasive infections.

Multispecies probiotic supplementation in diet with reduced crude protein levels altered the composition and function of gut microbiome and restored microbiome-derived metabolites in growing pigs

Both crude protein (CP) and probiotics can modulate the gut microbiome of the host, thus conferring beneficial effects. However, the benefits of low CP diet supplemented with multispecies probiotics on gut microbiome and its metabolites have not been investigated in pigs. Thus, we investigated the combinatory effects of low CP diet supplemented with multispecies probiotics on gut microbiome composition, function, and microbial metabolites in growing pigs. In total, 140 6 week-old piglets (Landrace × Yorkshire × Duroc) were used in this study. The pigs were divided into four groups with a 2 × 2 factorial design based on their diets: normal-level protein diet (16% CP; NP), low-level protein diet (14% CP; LP), NP with multispecies probiotics (NP-P), and LP with multispecies probiotics (LP-P). After the feeding trial, the fecal samples of the pigs were analyzed. The fecal scores were improved by the probiotic supplementation, especially in LP-P group. We also observed a probiotic-mediated alteration in the gut microbiome of pigs. In addition, LP-P group showed higher species richness and diversity compared with other groups. The addition of multispecies probiotics in low CP diet also enhanced gut microbiota metabolites production, such as short-chain fatty acids (SCFAs) and polyamines. Correlation analysis revealed that Oscillospiraceae UCG-002, Eubacterium coprostanoligenes, Lachnospiraceae NK4A136 group, and Muribaculaceae were positively associated with SCFAs; and Prevotella, Eubacterium ruminantium, Catenibacterium, Alloprevotella, Prevotellaceae NK3B31 group, Roseburia, Butyrivibrio, and Dialister were positively correlated with polyamines. Supplementation with multispecies probiotics modulated the function of the gut microbiome by upregulating the pathways for protein digestion and utilization, potentially contributing to enriched metabolite production in the gut. The results of this study demonstrate that supplementation with multispecies probiotics may complement the beneficial effects of low CP levels in pig feed. These findings may help formulate sustainable feeding strategies for swine production.

Effects of Food Factors and Processing on Protein Digestibility and Gut Microbiota

Protein is an essential macronutrient. The nutritional needs of dietary proteins are met by digestion and absorption in the small intestine. Indigestible proteins are further metabolized in the gut and produce metabolites via protein fermentation. Thus, protein indigestibility exerts a wide range of effects on gut microbiota composition and function. This review aims to discuss protein digestibility, the effects of food factors, such as protein sources, intake level, and amino acid composition, and making meat analogues. Besides, it provides an inventory of antinutritional factors and processing techniques that influence protein digestibility and, consequently, the diversity and composition of intestinal microbiota. Future studies are warranted to understand the implication of plant-based analogues on protein digestibility and gut microbiota and to elucidate the mechanisms concerning protein digestibility to host gut microbiota using various omics techniques.

Association of Gut Lachnospiraceae and Chronic Spontaneous Urticaria

(1) Background: Chronic spontaneous urticaria (CSU) has been linked to the dysbiosis of the gut microbiota. Furthermore, various studies have highlighted the anti-inflammatory properties of short-chain fatty acids (SCFAs), whose production is primarily regulated by the gut microbiota. However, only a few studies have investigated the role of major SCFA producers, such as Lachnospiraceae, in skin inflammatory diseases. (2) Goal: This study aimed to compare the abundance of Lachnospiraceae between CSU patients and healthy controls (HCs). (3) Material and methods: In this case-control study, 16S rRNA sequencing was performed to compare the composition of the gut microbiome between 22 CSU patients and 23 HCs. (4) Results: Beta-diversity revealed significant clustering (p < 0.05) between the CSU patients and HCs. Alpha diversity in the CSU group was significantly decreased according to the Evenness index (p < 0.05). The linear discriminant analysis effect size (LEfSe) identified the significant depletion of the Lachnospiraceae family in CSU patients. (5) Conclusion: Our study revealed the dysbiosis of the gut microbiota in CSU patients, including decreased levels of Lachnospiraceae members, responsible for SCFA production, suggesting that SCFAs may contribute to immune dysfunction in the pathogenesis of CSU. We speculate that the modulation of SCFAs could serve as a prospective additional option in CSU treatment.

Association of Gut Lachnospiraceae and Chronic Spontaneous Urticaria

(1) Background: Chronic spontaneous urticaria (CSU) has been linked to the dysbiosis of the gut microbiota. Furthermore, various studies have highlighted the anti-inflammatory properties of short-chain fatty acids (SCFAs), whose production is primarily regulated by the gut microbiota. However, only a few studies have investigated the role of major SCFA producers, such as Lachnospiraceae, in skin inflammatory diseases. (2) Goal: This study aimed to compare the abundance of Lachnospiraceae between CSU patients and healthy controls (HCs). (3) Material and methods: In this case–control study, 16S rRNA sequencing was performed to compare the composition of the gut microbiome between 22 CSU patients and 23 HCs. (4) Results: Beta-diversity revealed significant clustering (p < 0.05) between the CSU patients and HCs. Alpha diversity in the CSU group was significantly decreased according to the Evenness index (p < 0.05). The linear discriminant analysis effect size (LEfSe) identified the significant depletion of the Lachnospiraceae family in CSU patients. (5) Conclusion: Our study revealed the dysbiosis of the gut microbiota in CSU patients, including decreased levels of Lachnospiraceae members, responsible for SCFA production, suggesting that SCFAs may contribute to immune dysfunction in the pathogenesis of CSU. We speculate that the modulation of SCFAs could serve as a prospective additional option in CSU treatment.

Marine Fish Protein Peptide Regulating Potassium Oxonate-Induced Intestinal Dysfunction in Hyperuricemia Rats Helps Alleviate Kidney Inflammation

The metabolic disease hyperuricemia (HUA) is characterized by a disturbance in purine metabolism. Peptides, such as marine fish-derived peptides, have previously been shown to be effective in alleviating HUA. In this study, HUA rats were induced by potassium oxonate with 100 mg/kg (L), 200 mg/kg (M), and 400 mg/kg (H) of marine fish protein peptide (MFPP). The results showed that MFPP could effectively reduce the serum uric acid (SUA) levels compared with the model group rats; kidney histopathology and the levels of inflammatory factors (TNF-α, IL-6, and IL-10) indicated that MFPP attenuated HUA-induced kidney inflammation. Meanwhile, MFPP restored the abundance of beneficial bacteria, including Lactobacillus, Blautia, Colidextribacter, and Intestinimonas. MFPP further repaired the intestinal barrier by recovering the expression of gene Ildr2 encoding the tricellular tight junction protein ILDR2 and the immune-related genes Ccr7 and Nr4a3 and also regulated the expression of Entpd8 and Cyp27b1 to restore kidney function and uric acid metabolism. MFPP was proved to have potential as a therapeutic strategy to be included in dietary intervention to relieve HUA.

Impact of ileal indigestible protein on fecal nitrogen excretion and fecal microbiota may be greater compared with total protein concentration of diets in growing pigs

In the current study, we hypothesized that an increase in dietary ileal indigestible protein concentration induces an increase in hindgut nitrogen utilization and nitrogen excretion and a shift in fecal microbiota in growing pigs, when compared to pigs given a high total protein diet. Three diets were prepared: 1) standard protein diet based on corn and soybean meal, 2) high-indigestible protein diet in which autoclaved, low-digestible soybean meal replaced soybean meal in the first diet, and 3) high protein diet where the inclusion rate of soybean meal was greater than that of the other diets. The 3 diets were fed to 18 barrows that were fitted with T-cannula at the ileo-cecal junction (initial body weight = 63.4 ± 8.0 kg) in a randomized complete block design with body weight as a blocking factor. Pigs were individually housed in pens and the experiment lasted for 23 d. On days 7 and 21, fecal samples were collected by rectal massage for microbiota analysis. Grab samples of feces were collected on days 20 and 21, and ileal digesta were collected on days 22 and 23 for the determination of energy and nitrogen utilization. Lower apparent ileal digestibility of nitrogen in the high-indigestible protein diet containing autoclaved soybean meal resulted in greater ileal indigestible nitrogen concentration (P < 0.05). Apparent total tract digestibility of nitrogen was lower (P < 0.05), and correspondingly nitrogen concentration and daily fecal nitrogen output were greater (P < 0.05) in the high-indigestible protein diet compared with the other diets. Apparent post-ileal digestibility and hindgut disappearance of nitrogen and gross energy were the greatest (P < 0.05) in the high protein diet, whereas a statistical difference was not observed in those variables between the standard protein diet and the high-indigestible protein diet. Beta diversity metrics of feces in the high-indigestible protein diet on day 21 were different (q < 0.05) from those in the other two diets, which indicates a shift in microbial communities. According to the results of the DESeq2, the direction of microbiota shift induced by the high-indigestible protein diet may have reduced fiber utilization in the hindgut. In conclusion, an increase in dietary ileal indigestible protein concentration increased fecal nitrogen excretion and shifted fecal microbial communities but did not increase nitrogen utilization in the hindgut.

Amino acid utilization allows intestinal dominance of Lactobacillus amylovorus

The mammalian intestine harbors heterogeneous distribution of microbes among which specific taxa (e.g. Lactobacillus) dominate across mammals. Deterministic factors such as nutrient availability and utilization may affect microbial distributions. Due to physiological complexity, mechanisms linking nutrient utilization and the dominance of key taxa remain unclear. Lactobacillus amylovorus is a predominant species in the small intestine of pigs. Employing a pig model, we found that the small intestine was dominated by Lactobacillus and particularly L. amylovorus, and enriched with peptide-bound amino acids (PBAAs), all of which were further boosted after a peptide-rich diet. To investigate the bacterial growth dominance mechanism, a representative strain L. amylovorus S1 was isolated from the small intestine and anaerobically cultured in media with free amino acids or peptides as sole nitrogen sources. L. amylovorus S1 grew preferentially with peptide-rich rather than amino acid-rich substrates, as reflected by enhanced growth and PBAA utilization, and peptide transporter upregulations. Utilization of free amino acids (e.g. methionine, valine, lysine) and expressions of transporters and metabolic enzymes were enhanced simultaneously in peptide-rich substrate. Additionally, lactate was elevated in peptide-rich substrates while acetate in amino acid-rich substrates, indicating distinct metabolic patterns depending on substrate forms. These results suggest that an increased capability of utilizing PBAAs contributes to the dominance of L. amylovorus, indicating amino acid utilization as a deterministic factor affecting intestinal microbial distribution. These findings may provide new insights into the microbe-gut nutrition interplay and guidelines for dietary manipulations toward gut health especially small intestine health.

Digestion Profiles of Protein in Edible Pork By-Products

Edible pork by-products are widely consumed in many areas, whereas their digestion characteristics have rarely been evaluated. This work compared the digestibility of protein in boiled pork liver, heart, tripe and skin with tenderloin as a control. Cooked skin showed the highest digestibility in the simulated gastric digestion, whereas its gastric digests were less digested in the simulated intestinal stage. In contrast, cooked tripe showed the lowest gastric digestibility but relatively higher intestinal digestibility. All the edible by-products showed lower digestibility than tenderloin, especially for pork liver, in which large undigested fractions (>300 μm) could be observed. Corresponding to these results, larger amount of bigger peptides was found in the digests of pork liver and skin. In addition, peptides in tripe (average bioactive probability = 0.385) and liver digests (average bioactive probability = 0.386) showed higher average bioactive probability than other samples. Tripe digests contained the highest level of free Asp, Gln, Cys, Val, Phe, Pro, Ser, Thr, Ile and Asn, whereas heart digests contained the highest level of free Leu, Met and Arg. These results could help to reveal the nutrition value of pork by-products.

Polysaccharides from fermented coix seed modulates circulating nitrogen and immune function by altering gut microbiota

Coix lachryma-jobi L. seed is an important food item in Asia with culinary and medicinal values. The effects of non-fermented coix seed (NFC), fermented coix seed with Lactobacillus plantarum NCU137 (FC) and polysaccharides from NFC, FC (FCP) on mice circulating nitrogen and immune disorder induced by high relative humidity (RH, 90 ± 2%) exposure were compared. All the treatments reduced circulating nitrogen (BUN and ammonia) might via increasing excretion of fecal nitrogen induced by altering gut microbiota. In comparison, FC and FCP restored erythrocyte morphology by promoting erythrocyte Na⁺/K⁺ ATPase activity more effectively, and immune function was modulated by reducing plasma IgM and IFN-γ levels, up-regulating IL-4 and IL-6 levels. Herein, these results indicated that FCP, as the main active ingredient in FC, modulated circulating nitrogen through altering gut microbiota, and restored immune homeostasis by regulating Th1/Th2 cytokines in mice receiving high RH exposure.

Characterization of diet-dependent temporal changes in circulating short-chain fatty acid concentrations: A randomized crossover dietary trial

BACKGROUND

Production of SCFAs from food is a complex and dynamic saccharolytic fermentation process mediated by both human and gut microbial factors. Knowledge of SCFA production and of the relation between SCFA profiles and dietary patterns is lacking.

OBJECTIVES

Temporal changes in SCFA concentrations in response to 2 contrasting diets were investigated using a novel GC-MS method.

METHODS

Samples were obtained from a randomized, controlled, crossover trial designed to characterize the metabolic response to 4 diets. Participants (n = 19) undertook these diets during an inpatient stay (of 72 h). Serum samples were collected 2 h after breakfast (AB), after lunch (AL), and after dinner (AD) on day 3, and a fasting sample (FA) was obtained on day 4. The 24-h urine samples were collected on day 3. In this substudy, samples from the 2 extreme diets representing a diet with high adherence to WHO healthy eating recommendations and a typical Western diet were analyzed using a bespoke GC-MS method developed to detect and quantify 10 SCFAs and precursors in serum and urine samples.

RESULTS

Considerable interindividual variation in serum SCFA concentrations was observed across all time points, and temporal fluctuations were observed for both diets. Although the sample collection timing exerted a greater magnitude of effect on circulating SCFA concentrations, the unhealthy diet was associated with a lower concentration of acetic acid (FA: coefficient: -17.0; SE: 5.8; P-trend = 0.00615), 2-methylbutyric acid (AL: coefficient: -0.1; SE: 0.028; P-trend = 4.13 × 10-4 and AD: coefficient: -0.1; SE: 0.028; P-trend = 2.28 × 10-3), and 2-hydroxybutyric acid (FA: coefficient: -15.8; SE: 5.11; P-trend: 4.09 × 10-3). In contrast, lactic acid was significantly higher in the unhealthy diet (AL: coefficient: 750.2; SE: 315.2; P-trend = 0.024 and AD: coefficient: 1219.3; SE: 322.6; P-trend: 8.28 × 10-4).

CONCLUSIONS

The GC-MS method allowed robust mapping of diurnal patterns in SCFA concentrations, which were affected by diet, and highlighted the importance of standardizing the timing of SCFA measurements in dietary studies. This trial was registered on the NIHR UK clinical trial gateway and with ISRCTN as ISRCTN43087333.

Resistant Protein: Forms and Functions

Several global health risks are related to our dietary lifestyle. As a consequence of the overconsumption of ultra-processed and highly digestible protein (150–200% of the recommended value), excess dietary proteins reach the colon, are hydrolysed to peptides and amino acids by bacterial proteases and fermented to various potentially toxic end products. A diet reformulation strategy with reduced protein content in food products appears to be the most effective approach. A potential approach to this challenge is to reduce food digestibility by introducing resistant protein into the diet that could positively influence human health and gut microbiome functionality. Resistant protein is a dietary constituent not hydrolysed by digestive enzymes or absorbed in the human small intestine. The chemical conformation and the amino acid composition strictly influence its structural stability and resistance to in vivo proteolysis and denaturation. Responding to the important gap in our knowledge regarding the digestibility performance of alternative proteins, we hypothesise that resistant proteins can beneficially alter food functionality via their role in improving metabolic properties and health benefits in human nutrition, similar to fibres and resistant starches. A multidisciplinary investigation of resistant protein will generate tremendous scientific impact for other interlinked societal, economic, technological and health and wellbeing aspects of human life.

Relationship between Changes in Intestinal Microorganisms and Effect of High Temperature on the Growth and Development of Bombyx mori Larvae

Temperature is an important environmental factor affecting the growth and development of silkworm (Bombyx mori). To analyze the effect of intestinal microbes on silkworm in response to a high-temperature environment, this study used a combination of high throughput sequencing and biochemical assays to detect silkworm intestinal microbes treated with high temperature for 72 h. The results show that high temperature affects the intestinal microbes of silkworm and that there are sex differences, specifically, females were more sensitive. The changes in the metabolism and transport ability of silkworm intestinal tissues under high temperature are related to the intestinal microbes. High temperatures may affect the intestinal microbes of silkworms, regulating the activity of related digestive enzymes and substance transport in the intestine, thereby affecting the silkworm’s digestion and absorption of nutrients, and ultimately affecting growth and development.

Tissue-wide metabolomics reveals wide impact of gut microbiota on mice metabolite composition

The essential role of gut microbiota in health and disease is well recognized, but the biochemical details that underlie the beneficial impact remain largely undefined. To maintain its stability, microbiota participates in an interactive host-microbiota metabolic signaling, impacting metabolic phenotypes of the host. Dysbiosis of microbiota results in alteration of certain microbial and host metabolites. Identifying these markers could enhance early detection of certain diseases. We report LC-MS based non-targeted metabolic profiling that demonstrates a large effect of gut microbiota on mammalian tissue metabolites. It was hypothesized that gut microbiota influences the overall biochemistry of host metabolome and this effect is tissue-specific. Thirteen different tissues from germ-free (GF) and conventionally-raised (MPF) C57BL/6NTac mice were selected and their metabolic differences were analyzed. Our study demonstrated a large effect of microbiota on mammalian biochemistry at different tissues and resulted in statistically-significant modulation of metabolites from multiple metabolic pathways (p ≤ 0.05). Hundreds of molecular features were detected exclusively in one mouse group, with the majority of these being unique to specific tissue. A vast metabolic response of host to metabolites generated by the microbiota was observed, suggesting gut microbiota has a direct impact on host metabolism.

Dysbiosis and Migraine Headaches in Adults With Celiac Disease

One of the most significant illnesses associated with gluten is celiac disease, which encompasses many conditions. It is generally recognized that neurological manifestations can occur either at the time of the disease onset or as the illness continues to develop. One of the main clinical presentations of celiac disease is headache, either in the form of migraine or in an unspecific form. Migraine pathophysiology is intricate and still poorly understood. Several mechanisms involving the gut-brain axis have been proposed to explain this association. These include the interaction of chronic inflammation with inflammatory and vasoactive mediators, the modulation of the intestinal immune environment of the microbiota, and the dysfunction of the autonomic nervous system. However, further research is required to fully comprehend the fundamental mechanisms and pathways at play. This review aims to give a narrative summary of the literature on celiac disease's neurological symptoms, particularly migraines, and to assess any potential associations to dysbiosis, an imbalance in the microbiome.

Analyzing macromolecular composition of E. Coli O157:H7 using Raman-stable isotope probing

Metabolic dynamics of bacterial cells is needed for understanding the correlation between changes in environmental conditions and cell metabolic activity. In this study, Raman spectroscopy combined with deuterium labelling was used to analyze the metabolic activity of a single Escherichia coli O157:H7 cell. The incorporation of deuterium from heavy water into cellular biomolecules resulted in the formation of carbon-deuterium (CD) peaks in the Raman spectra, indicating the cell metabolic activity. The broad vibrational peaks corresponding to CD and CH peaks encompassed different specific shifts of macromolecules such as protein, lipids, and nucleic acid. The utilization of tryptophan and oleic acid by the cell as the sole carbon source led to changes in cell lipid composition, as indicated by new peaks in the second derivative spectra. Thus, the proposed method could semi-quantitatively determine total metabolic activity, macromolecule specific identification, and lipid and protein metabolism in a single cell.

Special Diets in Infants and Children and Impact on Gut Microbioma

Gut microbiota is a complex system that starts to take shape early in life. Several factors influence the rise of microbial gut colonization, such as term and mode of delivery, exposure to antibiotics, maternal diet, presence of siblings and family members, pets, genetics, local environment, and geographical location. Breastfeeding, complementary feeding, and later dietary patterns during infancy and toddlerhood are major players in the proper development of microbial communities. Nonetheless, if dysbiosis occurs, gut microbiota may remain impaired throughout life, leading to deleterious consequences, such as greater predisposition to non-communicable diseases, more susceptible immune system and altered gut–brain axis. Children with specific diseases (i.e., food allergies, inborn errors of metabolism, celiac disease) need a special formula and later a special diet, excluding certain foods or nutrients. We searched on PubMed/Medline, Scopus and Embase for relevant pediatric studies published over the last twenty years on gut microbiota dietary patterns and excluded case reports or series and letters. The aim of this review is to highlight the changes in the gut microbiota in infants and children fed with special formula or diets for therapeutic requirements and, its potential health implications, with respect to gut microbiota under standard diets.

Structural characteristics of sulfated polysaccharides from Sargassum horneri and immune-enhancing activity of polysaccharides combined with lactic acid bacteria

Sargassum horneri (SH), a marine brown alga, is known to contain a variety of bioactive ingredients and previous studies reported sulfated polysaccharides in SH as a potential candidate for a functional ingredient. However, immune-enhancing activity combined with Lactobacillus plantarum (LAB) is not yet studied. In the present study, we attempted to characterize sulfated polysaccharides (SHCPs) in SH by MALDI-TOF/TOF mass spectrometry and evaluate their immune-enhancing effect on macrophage cells. The main residue of SHCPs in SH is 2-sulfated 1,4-linked L-fucose and this epitope combined with LAB shows immune enhancement properties through cytokine production at the cellular level and increases the population of lymphocytes and myelomonocytes in the adult zebrafish kidney. These results indicate that SHCPs, along with LAB, have potent immune-enhancing activity and may be utilized as a potential immunomodulatory ingredient.

Resistant lactic acidemia due to accidental cheese starter culture ingestion: A case report

Lactic acid is the end-product of anaerobic glycolysis. It is generally believed that elevated blood lactate levels are associated with poor patient outcomes. Literature reports that lactic acidosis can be related to supplementary food intake in the pediatric age group however, in adult patients, it is not common to see lactic acidosis due to oral ingestion unless the patient has a history of short bowel syndrome or jejunoileal bypass surgery. With the current case presentation, we report an accidental cheese starter culture intake that resulted in resistant lactic acidosis with no signs of critical illnesses.

Metagenomic insights into the microbe-mediated B and K2 vitamin biosynthesis in the gastrointestinal microbiome of ruminants

BACKGROUND

B and K₂ vitamins, essential nutrients in host metabolism, can be synthesized by the rumen microbiome in ruminants and subsequently absorbed by the host. However, the B and K₂ vitamin biosynthesis by the whole gastrointestinal microbiome and their abundances in different dietary strategies are largely unknown. Here, we reanalyzed our previous large-scale metagenomic data on the gastrointestinal microbiome of seven ruminant species and recruited 17,425 nonredundant microbial genomes from published datasets to gain a comprehensive understanding of the microbe-mediated B and K₂ vitamin biosynthesis in ruminants.

RESULTS

We identified 1,135,807 genes and 167 enzymes involved in B and K₂ vitamin biosynthesis. Our results indicated that the total abundances of B and K₂ vitamin biosynthesis were dominant in the stomach microbiome, while the biosynthesis of thiamine, niacin, and pyridoxine was more abundant in the large intestine. By examining 17,425 nonredundant genomes, we identified 2366 high-quality genomes that were predicted to de novo biosynthesize at least one vitamin. Genomic analysis suggested that only 2.7% of these genomes can synthesize five or more vitamins, and nearly half of genomes can synthesize only one vitamin. Moreover, we found that most genomes possessed cobalamin transporters or cobalamin-dependent enzymes to consume cobalamin directly, and only a few microbial genomes possessed a complete cobalamin biosynthesis pathway. Based on these genomic data, we examined the effect of the high-grain (HG) diet on the vitamin biosynthesis of the rumen microbiome of dairy cattle. We revealed that most vitamin biosynthesis was enhanced in the HG group, while only cobalamin synthesis was inhibited in the HG group, indicating that dietary fiber is vital for cobalamin biosynthesis.

CONCLUSIONS

We primarily provided a gene catalog and 2366 microbial genomes involved in B and K₂ vitamin biosynthesis in ruminants. Our findings demonstrated the regional heterogeneity and dietary effect of vitamin biosynthetic potential in the ruminant gastrointestinal microbiome and interpreted the biosynthesis mechanisms of these microbes and their physiological adaptability. This study expands our understanding of microbe-mediated vitamin biosynthesis in ruminants and may provide novel targets for manipulation to improve the production of these essential vitamins. Video abstract.

Body weight index indicates the responses of the fecal microbiota, metabolome and proteome to beef/chicken-based diet alterations in Chinese volunteers

Relationships between meat consumption and gut diseases have been debated for decades, and the gut microbiota plays an important role in this interplay. It was speculated that the gut microbiota and relevant indicators of hosts with different body weight indexes (BMIs) might respond differentially to meat-based diet alterations, since lean and obese hosts have different gut microbiota composition. Forty-five young Chinese volunteers were recruited and assigned to high-, middle- and low-BMI groups. All of the volunteers were given a beef-based diet for 2 weeks and subsequently with a chicken-based diet for another 2 weeks. Body weight and blood indexes were measured, and fecal samples were obtained for 16S rRNA sequencing, metabolome and proteome analyses. The fecal metabolites of the low-BMI volunteers showed greater sensitivity to meat-based diet alterations. In contrast, the fecal proteome profiles and blood indexes of the high- and middle-BMI volunteers indicated greater sensitivity to meat-based diet alterations. Replacing the beef-based diet with the chicken-based diet largely changed operational taxonomic units of Bacteroides genus, and thus probably induced downregulation of immunoglobulins in feces. Compared with the beef-based diet, the chicken-based diet decreased inflammation-related blood indexes, especially in high- and middle-BMI volunteers. This work highlighted the role of BMI as an important factor predicting changes in gut homeostasis in response to meat consumption. Compared with the chicken-based diet, the beef-based diet may induce more allergic and inflammation-related responses in high- and middle- BMI Chinese at the current level.

High ambient humidity aggravates ammonia-induced respiratory mucosal inflammation by eliciting Th1/Th2 imbalance and NF-κB pathway activation in laying hens

Ammonia (NH₃) is an irritant and harmful gas. Its accumulation in the poultry house poses detrimental effects on the respiratory mucosal system of birds. In this process, the relative humidity of the poultry house also plays an important role in potentiating the adverse effects of NH₃ on the respiratory status of birds, causing severe physiological consequences. In this study, the combined effects of NH₃ and humidity on the respiratory mucosal barrier of laying hens was studied. The gene expression of tight junction proteins, mucin, inflammatory cytokines secreted by Th1/Th2 cells, and proteins related to the Nuclear factor-κB (NF-κB) signaling pathway were detected by qRT-PCR. In addition, the contents of mucin and secretory immunoglobulin A (SIgA) in bronchoalveolar lavage fluid (BALF) were determined. The results showed that treatment with NH₃ alone or NH₃ and humidity led to morphological changes in the respiratory tract, decreased the gene expressions of tight junction protein, and increased the expression of mucin. Also, the expression of interleukin-4 (IL-4) and IL-10 were increased, whereas, the expression of interferon-γ (IFN-γ) and IL-2 was decreased in laying hens treated with NH₃ and humidity. Furthermore, the activation of inhibitor kappa B kinase β (I-KK-β) and the degradation of inhibitor of NF-κB α (I-κB-α) contributed to the activation of the NF-κB pathway, such that the downstream genes, cycooxygenase 2 (COX2) and inducible nitric oxide synthase (iNOS) were significantly increased. In conclusion, NH₃ damaged the mucosal barrier and induced an imbalance in the mucosal immunity, leading to respiratory tract inflammation. Thus, the relative humidity of the environment aggravates the adverse effects of NH₃ in poultry.

Role of dietary amino acids and microbial metabolites in the regulation of pig intestinal health

With the rapid development of sequencing technology, research on pigs has focused on intestinal microbes. Accumulating evidence suggests that the metabolites of intestinal microbes are the key medium for interactions between microbes and the host. Amino acid metabolism is involved in the growth and immune processes of pigs. The gut microbes of pigs are heavily involved in the metabolism of amino acids in their hosts. Here, we review the latest relevant literature. Research findings show that microbial metabolites, such as indoles, short-chain fatty acids, and ammonia, play a key role in gut health. Moreover, we summarize the effects of amino acids on the structure of the gut microbial community and the metabolism of amino acids by pig gut microbes. Evidence shows that microbial amino acid metabolites act as signal molecules in the intestine and play an important role in the intestinal health of pigs.

Reconsidering Meat Intake and Human Health: A Review of Current Research

Meat consumption is gradually increasing and its impact on health has attracted widespread attention, resulting in epidemiological studies proposing a reduction in meat and processed meat intake. This review briefly summarizes recent advances in understanding the effects of meat or processed meat on human health, as well as the underlying mechanisms. Meat consumption varies widely among individuals, populations, and regions, with higher consumption in developed countries than in developing countries. However, increasing meat consumption may not be the main cause of increasing incidence of chronic disease, since the development of chronic disease is a complex physiological process that involves many factors, including excessive total energy intake and changes in food digestion processes, gut microbiota composition, and liver metabolism. In comparison, unhealthy dietary habits and a sedentary lifestyle with decreasing energy expenditure are factors more worthy of reflection. Meat and meat products provide high-value protein and many key essential micronutrients. In short, as long as excessive intake and overprocessing of meats are avoided, meat remains an indispensable source of nutrition for human health.

What we know about protein gut metabolites: Implications and insights for human health and diseases

Gut microbiota is a complex ecosystem of symbiotic bacteria that contribute to human metabolism and supply intestinal metabolites, whose production is mainly influenced by the diet. Dietary patterns characterized by a high intake of protein promotes the growth of proteolytic bacteria's, which produce metabolites from undigested protein fermentation. Microbioal protein metabolites can regulate immune, metabolic and neuronal responses in different target organs. Metabolic pathways of these compounds and their mechanisms of action on different pathologies can lead to the discovery of new diagnostic techniques, drugs and the potential use as functional ingredients in food. This review discusses the potential mechanisms by which amino acid catabolism is involved in microbial protein metabolites. In addition, results from several studies on the association of products from the intestinal metabolism of indigestible proteins and the state of health or disease of the host are revised.

In Vitro Gut Fermentation of Whey Protein Hydrolysate: An Evaluation of Its Potential Modulation on Infant Gut Microbiome

Whey protein and its hydrolysate are ubiquitously consumed as nutritional supplements. This study aimed to evaluate the potential effect of whey protein hydrolysate (WPH) on the infant gut microbiome, which is more variable than that of adults. Colonic fermentation was simulated through a static digestion model and fecal culture fermentation, using feces from normal infants aged from 1−3 years old. During in vitro gut fermentation, measurements of short-chain fatty acids (SCFA) concentrations and 16S rRNA amplicon sequencing were performed. Additionally, the growth curves of cultivated probiotics were analyzed to evaluate the prebiotic potential of WPH. Besides the decline of pH in fermentation, the addition of WPH induced a significant increase in the SCFA production and also the relative abundance of Proteobacteria, Bacteroides, and Streptococcus (p < 0.05). The lower ratio of Firmicutes/Bacteroidetes in WPH-supplemented samples indicated the positive modulation of WPH on the gut microbiota, which could benefit the energy balance and metabolism of infants. The stimulation effect of WPH on the probiotics (particularly Lactobacillus acidophilus NCFM) during cultivation implied the prebiotic potential as well. Our findings shed light on WPH as a valuable dietary supplement with not only enriched resources of essential amino acids but also the potential to restore the infant gut microbiome.

The Macronutrient Composition of Infant Formula Produces Differences in Gut Microbiota Maturation That Associate with Weight Gain Velocity and Weight Status

This proof-of-principle study analyzed fecal samples from 30 infants who participated in a randomized controlled trial on the effects of the macronutrient composition of infant formula on growth and energy balance. In that study, infants randomized to be fed cow milk formula (CMF) had faster weight-gain velocity during the first 4 months and higher weight-for-length Z scores up to 11.5 months than those randomized to an isocaloric extensive protein hydrolysate formula (EHF). Here we examined associations among infant formula composition, gut microbial composition and maturation, and children’s weight status. Fecal samples collected before and monthly up to 4.5 months after randomization were analyzed by shotgun metagenomic sequencing and targeted metabolomics. The EHF group had faster maturation of gut microbiota than the CMF group, and increased alpha diversity driven by Clostridia taxa. Abundance of Ruminococcus gnavus distinguished the two groups after exclusive feeding of the assigned formula for 3 months. Abundance of Clostridia at 3–4 months negatively correlated with prior weight-gain velocity and body weight phenotypes when they became toddlers. Macronutrient differences between the formulas likely led to the observed divergence in gut microbiota composition that was associated with differences in transient rapid weight gain, a well-established predictor of childhood obesity and other comorbidities.

Different dietary protein sources influence growth performance, antioxidant capacity, immunity, fecal microbiota and metabolites in weaned piglets

The inclusion of high-quality proteins are commonly used in swine production. Our research investigated the effects of hydrolyzed wheat protein (HWP), fermented soybean meal (FSBM), and enzyme-treated soybean meal (ESBM) on growth performance, antioxidant capacity, immunity, fecal microbiota and metabolites of weaned piglets. A total of 144 piglets (weaned at 28 d) were allotted to 3 dietary treatments with 6 replicate pens per treatment and 8 piglets per pen. This study included 2 periods: d 0 to14 for phase 1 and d 15 to 28 for phase 2. Dietary treatments contained 15.90% HWP, 15.80% FSBM, and 15.10% ESBM in phase 1, and 7.90% HWP, 7.80% FSBM, and 7.50% ESBM in phase 2, respectively. The ADG of piglets in ESBM was increased (P < 0.05) compared with HWP and FSBM during d 1-28. Compared with HWP and FSBM, ESBM increased (P < 0.05) the ferric reducing ability of plasma (FRAP), and the serum level of superoxide dismutase (SOD) in piglets on d 14, as well as increased (P < 0.05) the serum FRAP level in piglets on d 28. ESBM decreased (P < 0.05) serum levels of DAO and IL-1β in piglets compared with HWP on d 28. ESBM enhanced (P < 0.05) the relative abundance of Bacteroidetes, Oscillospiraceae and Christensenellaceae, as well as reduced the relative abundance of Clostridiaceae in the feces compared with HWP and FSBM. The PICRUSt analysis revealed that the number of gene tags related to degradation of valine, leucine and isoleucine, as well as lysine degradation in ESBM were lower (P < 0.05) than that in HWP and FSBM. ESBM increased (P < 0.05) the fecal butyrate level in piglets compared with FSBM, and ESBM tended to decrease (P = 0.076) the fecal cadaverine level. Overall, ESBM had advantages over HWP and FSBM in improving antioxidant status, immune function, fecal bacteria and metabolites for weaned piglets.

In vitro gastrointestinal digestion of Lentinus squarrosulus powder and impact on human fecal microbiota

Humans have long-used mushrooms as food and medicine, but digestion and colonic fermentation of most mushrooms, including Lentinus squarrosulus is markedly unknown. Here, nutritional profile, digestion and colonic fermentation of L. squarrosulus powder (LP) were determined. The powder contained mainly carbohydrate and protein. SEM and F-TIR analysis of the resistant hydrolysate (RH) revealed that the structure and ratio of carbohydrate and protein components were altered, and released known immunomodulation agents; beta-glucans and mannose. Both LP and RH promoted selected probiotic bacteria, especially Bifidobacterium strains. Using fecal microbiota of five volunteers (V1, V2, V3, V4 and V5), RH stimulated the microbiota of all used volunteers, via decreasing the ratio of Firmicutes/Bacteroidetes ranging from 1.3 to 8.2 times. Also, RH increased the relative abundance of vital immunomodulators; Bacteroides, Bifidobacterium, Clostridium cluster XIVa and IV, and Sutterella. Additionally, RH fermentation enriched the content of branch-chain fatty acids (BCFA) and short-chain fatty acids (SCFA), indicating protein and carbohydrate usage. Notably, propionic and butyric acids were abundant in V1, V2 and V3, while in V4 and V5, acetic and butyric acids were most enriched. Suggesting L. squarrosulus as functional mushroom to improve health and prevent diseases by enhancing gut health.

Real ileal amino acid digestibility of pea protein compared to casein in healthy humans: a randomized trial

BACKGROUND

It is necessary to propose plant alternatives to animal proteins that are of good nutritional quality. Pea is a good candidate owing to its high protein content and its well-balanced amino acid (AA) profile.

OBJECTIVES

This study aimed to assess the real ileal AA and nitrogen digestibility (RIDAA and RIDN) of pea protein isolate as compared to milk casein in humans. It also aimed to evaluate their nutritional quality through calculation of the digestible indispensable amino acid score (DIAAS) and to determine the net postprandial protein utilization (NPPU).

METHODS

Fifteen healthy volunteers were included in a randomized, single-blinded, 2-arm, parallel-design trial. They were equipped with a naso-ileal tube. They ingested the test meals, which consisted of 9 successive portions of mashed potatoes containing either pea protein or casein, intrinsically labeled with nitrogen 15. Ileal content, plasma, and urine samples were collected regularly over an 8-h postprandial period.

RESULTS

The mean RIDAA values were 93.6% ± 2.9% for pea protein and 96.8% ± 1.0% for casein, with no difference between the sources (P = 0.22). Leucine, valine, lysine, and phenylalanine were significantly less digestible in pea than in casein. The RIDN values were 92.0% ± 2.7% and 94.0% ± 1.7% for pea protein and casein, respectively, and were not different (P = 0.11). The DIAAS was 1.00 for pea protein and 1.45 for casein. The NPPU was 71.6% ± 6.2% and 71.2% ± 4.9% for pea protein and casein, respectively (P = 0.88).

CONCLUSIONS

Although some AAs are less digestible in pea protein than in casein, the real ileal digestibility and the NPPU were not different. The DIAAS of 1.00 obtained for pea protein demonstrated its ability to meet all AA requirements. This study shows the potential of pea isolate as a high-quality protein. This study was registered at clinicaltrials.gov as NCT04072770.

Effect of Dietary Protein and Processing on Gut Microbiota—A Systematic Review

The effect of diet on the composition of gut microbiota and the consequent impact on disease risk have been of expanding interest. The present review focuses on current insights of changes associated with dietary protein-induced gut microbial populations and examines their potential roles in the metabolism, health, and disease of animals. Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) protocol was used, and 29 highly relevant articles were obtained, which included 6 mouse studies, 7 pig studies, 15 rat studies, and 1 in vitro study. Analysis of these studies indicated that several factors, such as protein source, protein content, dietary composition (such as carbohydrate content), glycation of protein, processing factors, and protein oxidation, affect the digestibility and bioavailability of dietary proteins. These factors can influence protein fermentation, absorption, and functional properties in the gut and, consequently, impact the composition of gut microbiota and affect human health. While gut microbiota can release metabolites that can affect host physiology either positively or negatively, the selection of quality of protein and suitable food processing conditions are important to have a positive effect of dietary protein on gut microbiota and human health.

Short-chain fatty acids-microbiota crosstalk in the coronavirus disease (COVID-19)

The novel coronavirus disease (COVID-19) still remains a major challenge to the health-care systems worldwide, inciting ongoing search for pharmaceutical and non-pharmaceutical interventions which could benefit patients already infected with SARS-CoV-2 or at increased risk thereof. Although SARS-CoV-2 primarily affects the respiratory system, it may also infect other organs and systems, including gastrointestinal tract, where it results in microbial dysbiosis. There is an emerging understanding of the role the gut microbiota plays in maintaining immune homeostasis, both inside the gastrointestinal tract and beyond (i.e. through gut-lung and gut-brain axes). One family of compounds with recognized immunomodulatory and anti-inflammatory properties are short chain fatty acids (SCFAs). SCFAs are believed that they have a protective effect in case of gastrointestinal diseases. Moreover, they are responsible for maintaining proper intestinal barrier and they take part in relevant immune functions. This review presents mechanisms of action and potential benefits of SCFA-based probiotics and direct SCFA supplementation as a strategy to support immune function amid the COVID-19 pandemic.

Gastrointestinal microbiome and gluten in celiac disease

Coeliac disease (CD), also known as gluten sensitive enteropathy, is an autoimmune intestinal disease induced by gluten in genetically susceptible individuals. Gluten is a common ingredient in daily diet and is one of the main environmental factors to induce coeliac disease. Adhering to gluten free diet (GFD) is an effective method for treating CD. Microbiota plays an extremely important role in maintaining human health, and diet is the main factor to regulate the composition and function of gut microbiota. Recent studies have shown that gluten metabolism is closely related to gastrointestinal tract (GIT) microbiota. With the increasing prevalence of coeliac disease, there is a need for alternative treatments to GFD. In this review, biological medication of gluten, relationship between gluten and gut microflora, effect of GFD on GIT microflora, and effect of probiotics on CD were reviewed. By analysing the research progress on relationship between gluten and gastrointestinal microbiome in coeliac disease, this review tried to explore the prospective and potential mechanism of microecological agents in treating coeliac disease.

Effects of Saccharomyces cerevisiae cell wall addition on feed digestibility, fecal fermentation and microbiota and immunological parameters in adult cats

Background

This study aimed to evaluate the effects of increasing dosages of a commercial product composed by Saccharomyces cerevisiae yeast (YAM), with active metabolites, which are beta glucans, nucleotides, organic acids, polyphenols, amino acids, vitamins and minerals (Original XPC^tm, Diamond V, IOWA, USA) added to a commercially available dry cat food. Apparent digestibility of dietary nutrients, fecal microbiota, fecal fermentation products and immunological parameters were evaluated. Twenty-seven healthy cats of mixed sexes, with a mean body weight of 4.19 ± 0.83 kg and a mean age of 9.44 ± 5.35 years were distributed by age in an unbalanced randomized block design, consisting of three experimental treatments: CD (control diet), YAM 0.3 (control diet with 0.3% yeast with active metabolites) and YAM 0.6 (control diet with 0.6% yeast with active metabolites).

Results

The inclusion of the additive elevated the apparent digestibility of crude fiber (p = 0.013) and ash (p < 0.001) without interfering feed consumption, fecal production and fecal characteristics. Regarding fermentation products present in the feces, prebiotic inclusion increased lactic acid concentration (p = 0.004) while reducing isovaleric acid (p = 0.014), only in the treatment YAM 0.3. No differences were noticed on biogenic amines (BA), fecal pH, ammonia concentration, total and individuals short-chain fatty acids (SCFA) and total and individuals branched-chain fatty acids (BCFA) (except isovaleric acid in YAM 0.3). As regards to fecal microbiota, prebiotic inclusion has resulted in the reduction of Clostridium perfringens (p = 0.023). No differences were found in the immunological parameters evaluated.

Conclusion

It can be concluded that the additive, at the levels of inclusion assessed shows prebiotic potential and it has effects on fecal fermentation products and microbiota without interfering on crude protein and dry matter digestibility. More studies evaluating grater inclusion levels of the prebiotic are necessary to determine optimal concentration.