Microbial Fermentation of Dietary Protein: An Important Factor in Diet⁻Microbe⁻Host Interaction

Modulation of gut-microbiota through probiotics and dietary interventions to improve host health

Dietary patterns play an important role in regards to the modulation and control of the gut microbiome composition and function. The interaction between diet and microbiota plays an important role in order to maintain intestinal homeostasis, which ultimately affect the host's health. Diet directly impacts the microbes that inhabit the gastrointestinal tract (GIT), which then contributes to the production of secondary metabolites, such as short-chain fatty acids, neurotransmitters, and antimicrobial peptides. Dietary consumption with genetically modified probiotics can be the best vaccine delivery vector and protect cells from various illnesses. A holistic approach to disease prevention, treatment, and management takes these intrinsically linked diet-microbes, microbe-microbe interactions, and microbe-host interactions into account. Dietary components, such as fiber can modulate beneficial gut microbiota, and they have resulting ameliorative effects against metabolic disorders. Medical interventions, such as antibiotic drugs can conversely have detrimental effects on gut microbiota by disputing the balance between Bacteroides and firmicute, which contribute to continuing disease states. We summarize the known effects of various dietary components, such as fibers, carbohydrates, fatty acids, vitamins, minerals, proteins, phenolic acids, and antibiotics on the composition of the gut microbiota in this article in addition to the beneficial effect of genetically modified probiotics and consequentially their role in regards to shaping human health. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Unveiling the persistent threat: recent insights into Listeria monocytogenes adaptation, biofilm formation, and pathogenicity in foodborne infections

Listeriosis is a severe disease caused by the foodborne pathogen Listeria monocytogenes, posing a significant risk to vulnerable populations such as the elderly, pregnant women, and newborns. While relatively uncommon, it has a high global mortality rate of 20-30%. Recent research indicates that smaller outbreaks of the more severe, invasive form of the disease occur more frequently than previously thought, despite the overall stable infection rates of L. monocytogenes over the past 10 years. The ability of L. monocytogenes to form biofilm structures on various surfaces in food production environments contributes to its persistence and challenges in eradication, potentially leading to contamination of food and food production facilities. To address these concerns, this review focuses on recent developments in epidemiology, risk evaluations, and molecular mechanisms of L. monocytogenes survival in adverse conditions and environmental adaptation. Additionally, it covers new insights into strain variability, pathogenicity, mutations, and host vulnerability, emphasizing the important events framework that elucidates the biochemical pathways from ingestion to infection. Understanding the adaptation approaches of L. monocytogenes to environmental stress factors is crucial for the development of effective and affordable pathogen control techniques in the food industry, ensuring the safety of food production.

Gastrointestinal digestion of food proteins: Anticancer, antihypertensive, anti-obesity, and immunomodulatory mechanisms of the derived peptides

Food proteins and their peptides play a significant role in the important biological processes and physiological functions of the body. The peptides show diverse biological benefits ranging from anticancer to antihypertensive, anti-obesity, and immunomodulatory, among others. In this review, an overview of food protein digestion in the gastrointestinal tract and the mechanisms involved was presented. As some proteins remain resistant and undigested, the multifarious factors (e.g. protein type and structure, microbial composition, pH levels and redox potential, host factors, etc.) affecting their colonic fermentation, the derived peptides, and amino acids that evade intestinal digestion are thus considered. The section that follows focuses on the mechanisms of the peptides with anticancer, antihypertensive, anti-obesity, and immunomodulatory effects. As further considerations were made, it is concluded that clinical studies targeting a clear understanding of the gastrointestinal stability, bioavailability, and safety of food-based peptides are still warranted.

Digesting the complex metabolic effects of diet on the host and microbiome

The past 50 years of interdisciplinary research in humans and model organisms has delivered unprecedented insights into the mechanisms through which diet affects energy balance. However, translating these results to prevent and treat obesity and its associated diseases remains challenging. Given the vast scope of this literature, we focus this Review on recent conceptual advances in molecular nutrition targeting the management of energy balance, including emerging dietary and pharmaceutical interventions and their interactions with the human gut microbiome. Notably, multiple current dietary patterns of interest embrace moderate-to-high fat intake or prioritize the timing of eating over macronutrient intake. Furthermore, the rapid expansion of microbiome research findings has complicated multiple longstanding tenets of nutrition while also providing new opportunities for intervention. Continued progress promises more precise and reliable dietary recommendations that leverage our growing knowledge of the microbiome, the changing landscape of clinical interventions, and our molecular understanding of human biology.

The Severity of DSS-Induced Colitis Is Independent of the SCFA-FFAR2/3-GLP-1 Pathway Despite SCFAs Inducing GLP-1 Secretion via FFAR2/3

Short-chain fatty acids (SCFAs) are the major microbial metabolites produced from the fermentation of dietary fiber in the gut. They are recognised as secretagogues of the glucagon-like peptides, GLP-1 and GLP-2, likely mediated by the activation of free fatty acid receptors 2 and 3 (FFAR2 and 3) expressed on enteroendocrine L-cells. Fiber-deficient diets are associated with decreased intestinal function and decreased colonic GLP-1 and GLP-2 content. Here, we speculated that the lowered colonic GLP-1 observed following a fiber-free diet was a consequence of decreased SCFA production and a subsequent decrease in FFAR2/3 activation. Furthermore, we explored the consequences of a fiber-free diet followed by intestinal injury, and we mechanistically explored the SCFA-FFAR2/3-GLP-1 pathway to explain the increased severity. Colonic luminal content from mice fed either a fiber-free or chow diet were analysed for SCFA content by LC-MS. FFAR2/3 receptor contributions to SCFA-mediated colonic GLP-1 secretion were assessed in isolated perfused preparations of the colon from FFAR2/3 double knockout (KO) and wild-type (WT) mice. Colitis was induced by the delivery of 3% dextran sulfate sodium (DSS) for 4 days in the drinking water of mice exposed to a fiber-free diet for 21 days. Colitis was induced by the delivery of 3% DSS for 7 days in FFAR2/3 KO mice. The removal of dietary fiber significantly decreased SCFA concentrations in the luminal contents of fiber-free fed mice compared to chow-fed mice. In the perfused colon, luminal SCFAs significantly increased colonic GLP-1 secretion in WT mice but not in FFAR2/3 KO mice. In the DSS-induced colitis model, the removal of dietary fiber increased the severity and prevented the recovery from intestinal injury. Additionally, colitis severity was similar in FFAR2/3 KO and WT mice after DSS application. In conclusion, the results confirm that the removal of dietary fiber is sufficient to decrease the colonic concentrations of SCFAs. Additionally, we show that a fiber-free diet predisposes the colon to increased intestinal injury, but this effect is independent of FFAR2 and FFAR3 signalling; therefore, it is unlikely that a fiber-free diet induces a decrease in luminal SCFAs and sensitivity to intestinal disease involves the SCFA-FFAR2/3-GLP-1 pathway.

Fructooligosaccharides Ameliorate Renal Injury and Dysfunction Through the Modulation of Gut Dysbiosis, Inhibition of Renal Inflammation, Oxidative Stress, Fibrosis, and Improve Organic Anion Transporter 3 Function in an Obese Rat Model

SCOPE

High-fat diet (HFD) consumption causes obesity and gut dysbiosis which induces kidney injury. It has been reported that prebiotics improve gut dysbiosis and insulin sensitivity and decelerate the progression of kidney disease. This study investigates the impact of fructooligosaccharides (FOS) on renoprotection and the prevention of gut dysbiosis and intestinal barrier injury in obese rats.

METHODS AND RESULTS

Wistar rats are treated with HFD for 16 weeks. Then, the HFD fed rats (HF) are given FOS 1 g day-1 (HFFOS1), 2 g day-1 (HFFOS2), or metformin 30 mg kg-1 day-1 (HFMET), by intragastric feeding for 8 weeks. Blood, urine, feces, kidney, and intestine are collected to determine the metabolic changes, gut dysbiosis, and the expression of proteins involved in kidney and intestinal injury. FOS can attenuate insulin resistance and hypercholesterolemia concomitant with the inhibition of renal inflammation, oxidative stress, fibrosis, and apoptosis, which are related to the deceleration of the overexpression of renal Toll-like receptor 4 (TLR4) and NADPH oxidase (NOX4). Moreover, FOS shows a greater efficacy than metformin in the reduction of the intestinal injury and loss of tight junction proteins induced by HFD.

CONCLUSION

FOS may be used as a supplement for therapeutic purposes in an obese condition to improve intestinal integrity and prevent renal complications.

Microbial Population and Physicochemical Properties of Miang Fermented in Bamboo Tubes by the Luar Ethnic Group in Lao PDR

Miang is a traditional fermented food made from Assam tea leaves and consumed as a snack. This study investigated the underground Miang fermentation process practiced by the Luar ethnic group in Laos, specifically examining the nutritional composition and microbial dynamics. Lactic acid bacteria and yeast were dominant in the fermentation process, reaching 8.43 and 8.50 log CFU/g after one week before gradually declining, while the coliform bacterial count was at 5.31 log CFU/g in the initial week but became undetectable in the later stages of fermentation. Next-generation sequencing identified Firmicutes (75.02%) and Proteobacteria (23.51%) as the primary phyla. Bacterial genera included Lactobacillus (73.36%) and Acetobacter (21.06%), with fungi mainly represented by Pichia (85.52%) and Candida (13.45%). Fundamental microbes such as Lactobacillus and Acetobacter were predominantly present, alongside Pichia and Candida, in the fungal communities. Microbial activities played a crucial role in generating essential enzymes for Miang's transformation. The nutritional transformation appears to be complete at 5 weeks of fermentation. The moisture content in the final products was approximately 74% and correlated with a change in nitrogen-free extract (NFE) and crude fiber. The fat content showed a slight increase from 1.3% to 2.52%, but protein content slightly declined from 17.21% to 16.05%, whereas ash content did not change significantly. Key polysaccharide-degrading enzymes, particularly pectinase and β-mannanase, were revealed and peaked at 48.32 and 25.32 U/g Miang, respectively. The total polyphenols increased from 103.54 mg/g dry Miang to 144.19-155.52 mg/g during fermentation. The lowered IC50 value indicated an increase in antioxidant activity. A fermentation period of at least 3 weeks proved to be optimal for enhancing antioxidant properties and bioactive compounds, and mitigating the risk of coliform bacteria.

The individual response to antibiotics and diet - insights into gut microbial resilience and host metabolism

Antibiotic use disrupts microbial composition and activity in humans, but whether this disruption in turn affects host metabolic health is unclear. Cohort studies show associations between antibiotic use and an increased risk of developing obesity and type 2 diabetes mellitus. Here, we review available clinical trials and show the disruptive effect of antibiotic use on the gut microbiome in humans, as well as its impact on bile acid metabolism and microbial metabolites such as short-chain fatty acids. Placebo-controlled human studies do not show a consistent effect of antibiotic use on body weight and insulin sensitivity at a population level, but rather an individual-specific or subgroup-specific response. This response to antibiotic use is affected by the resistance and resilience of the gut microbiome, factors that determine the extent of disruption and the speed of recovery afterwards. Nutritional strategies to improve the composition and functionality of the gut microbiome, as well as its recovery after antibiotic use (for instance, with prebiotics), require a personalized approach to increase their efficacy. Improved insights into key factors that influence the individual-specific response to antibiotics and dietary intervention may lead to better efficacy in reversing or preventing antibiotic-induced microbial dysbiosis as well as strategies for preventing cardiometabolic diseases.

In Vitro Fermentation of Animal and Plant Protein Isolates by the Human Gut Microbiota Under High and Low Carbohydrate Conditions

SCOPE

There is a lack of research comparing how different protein isolates influence the microbiome, especially when carbohydrate (CHO) availability is varied. The objective is to determine changes in gut microbiota composition and function during fermentation of digested protein isolates under high and low CHO conditions.

METHODS AND RESULTS

Protein isolates from beef, egg white, milk, pea, and soy are subjected to in vitro digestion and fermentation with human fecal microbiota. Under low CHO conditions, the microbiota is primarily proteolytic with decreased concentrations of peptides and increased variance among microbial taxa and production of ammonia and branched chain fatty acids by the microbiota. Milk protein not only results in the highest production of butyrate and p-hydroxyphenylacetate but also has high concentrations of deleterious fermentation metabolites. Amino acid composition of the protein isolates is significantly correlated with abundances of many microbial taxa and metabolites, but the correlations are stronger in the low CHO medium.

CONCLUSION

This study shows that low CHO conditions increase proteolytic fermentation and result in increased differences in microbiota response to protein isolates. It also showed that amino acid composition is highly associated with microbiota composition and function especially under low CHO conditions.

Sustainable diets with plant-based proteins require considerations for prevention of proteolytic fermentation

The human diet requires a more plant-based approach due to the exhaustive effects animal-based foods have on the environment. However, plant-based proteins generally miss a few or have a lower variety in essential amino acids and are more difficult to digest. Subsequently they might be prone to fermentation by the microbiome in the proximal colon. Proteolytic fermentation can induce microbial-metabolites with beneficial and negative health effects. We review current insight into how balances in saccharolytic and proteolytic fermentation can be maintained when the diet consists predominantly of plant-based proteins. Some proteolytic fermentation metabolites may negatively impact balances in gut microbiota composition in the large intestine and influence immunity. However, proteolytic fermentation can potentially be prevented in the proximal colon toward more saccharolytic fermentation through the addition of non-digestible carbohydrates in the diet. Knowledge on this combination of plant-based proteins and non-digestible carbohydrates on colonic- and general health is limited. Current data suggest that transitioning toward a more plant-based protein diet should be accompanied with a consumption of increased quantities and more complex structures of carbohydrates or by application of technological strategies to enhances digestibility. This can reduce or prevent proteolytic fermentation which might consequently improve human health.

Feeling gutted in chronic kidney disease (CKD): Gastrointestinal disorders and therapies to improve gastrointestinal health in individuals CKD, including those undergoing dialysis

Chronic kidney disease (CKD) affects 9.1% of the population worldwide. CKD may lead to structural and functional gastrointestinal alterations, including impairment in the intestinal barrier, digestion and absorption of nutrients, motility, and changes to the gut microbiome. These changes can lead to increased gastrointestinal symptoms in people with CKD, even in early grades of kidney dysfunction. Gastrointestinal symptoms have been associated with lower quality of life and reduced nutritional status. Therefore, there has been considerable interest in improving gastrointestinal health in this clinical population. Gastrointestinal health can be influenced by lifestyle and medications, particularly in advanced grades of kidney dysfunction. Therapies focused on gastrointestinal health have been studied, including the use of probiotics, prebiotics, and synbiotics, yielding limited and conflicting results. This review summarizes the alterations in the gastrointestinal tract structure and function and provides an overview of potential nutritional interventions that kidney disease professionals can provide to improve gastrointestinal health in individuals with CKD.

Supplementing Monosodium Glutamate in Sow Diets Enhances Reproductive Performance in Lactating Sows and Improves the Growth of Suckling Piglets

In most current farm operations, lactating sows need to overcome reproductive and environmental stresses that have resulted in poor sow production performance and piglet growth. Therefore, this study aimed to investigate the effects of in-feed supplementation of monosodium glutamate (MSG) in sows during late gestation lactation in regard to litter performance. The study subjects were 12 multi-parity sows (Landrace × Large White), farrowing sows with an average parity of four (three with three parities, seven with four parities, and two with five parities). They were randomly divided into the following two diet groups: the basal diet as a control (CON) group based on corn and soybean meal; and the basal diet + 2% MSG group. The experimental time ranged from 109 days before delivery to 21 days after delivery. There were six sows in each group, and each sow served as the experimental unit. There were no significant differences (p > 0.05) in body weight (BW), back fat (BF) thickness and estrus interval between sows supplemented with 2% MSG in their diets before and after farrowing and during weaning (p > 0.05). However, MSG-treated sows tended to increase BW loss at farrowing more than the CON group (p = 0.093) but lost less weight during lactation than the CON group (p = 0.019). There were no significant differences in the body condition scores (BCSs) and BF loss of the two groups of sows before and after farrowing and at weaning (p > 0.05). There was no significant difference in the weight of newborn piglets between the two groups of sows (p > 0.05). The weaning weight (p = 0.020) and average daily gain (ADG) (p = 0.045) of suckling piglets were higher in the MSG treated group compared to the CON group. The daily milk production of sows in the MSG treatment group was higher compared to the CON group (p = 0.045). The protein concentration of milk at week 3 (p = 0.060) and fat concentration of milk at week 5 (p = 0.095) of the MSG-supplemented sows tended to increase more than the CON group. In summary, the dietary inclusion of MSG supplementation had a beneficial effect on the late gestating sows and their piglet's growth and milk production. Our research has shown that the addition of 2% MSG in late gestation and lactation diet would be beneficial for both sow and piglet production.

Summatory Effects of Anaerobic Exercise and a 'Westernized Athletic Diet' on Gut Dysbiosis and Chronic Low-Grade Metabolic Acidosis

Anaerobic exercise decreases systemic pH and increases metabolic acidosis in athletes, altering the acid-base homeostasis. In addition, nutritional recommendations advising athletes to intake higher amounts of proteins and simple carbohydrates (including from sport functional supplements) could be detrimental to restoring acid-base balance. Here, this specific nutrition could be classified as an acidic diet and defined as 'Westernized athletic nutrition'. The maintenance of a chronic physiological state of low-grade metabolic acidosis produces detrimental effects on systemic health, physical performance, and inflammation. Therefore, nutrition must be capable of compensating for systemic acidosis from anaerobic exercise. The healthy gut microbiota can contribute to improving health and physical performance in athletes and, specifically, decrease the systemic acidic load through the conversion of lactate from systemic circulation to short-chain fatty acids in the proximal colon. On the contrary, microbial dysbiosis results in negative consequences for host health and physical performance because it results in a greater accumulation of systemic lactate, hydrogen ions, carbon dioxide, bacterial endotoxins, bioamines, and immunogenic compounds that are transported through the epithelia into the blood circulation. In conclusion, the systemic metabolic acidosis resulting from anaerobic exercise can be aggravated through an acidic diet, promoting chronic, low-grade metabolic acidosis in athletes. The individuality of athletic training and nutrition must take into consideration the acid-base homeostasis to modulate microbiota and adaptive physiological responses.

Dietary nutrition, intestinal microbiota dysbiosis and post-weaning diarrhea in piglets

Weaning is a critical transitional point in the life cycle of piglets. Early weaning can lead to post-weaning syndrome, destroy the intestinal barrier function and microbiota homeostasis, cause diarrhea and threaten the health of piglets. The nutritional components of milk and solid foods consumed by newborn animals can affect the diversity and structure of their intestinal microbiota, and regulate post-weaning diarrhea in piglets. Therefore, this paper reviews the effects and mechanisms of different nutrients, including protein, dietary fiber, dietary fatty acids and dietary electrolyte balance, on diarrhea and health of piglets by regulating intestinal function. Protein is an essential nutrient for the growth of piglets; however, excessive intake will cause many harmful effects, such as allergic reactions, intestinal barrier dysfunction and pathogenic growth, eventually aggravating piglet diarrhea. Dietary fiber is a nutrient that alleviates post-weaning diarrhea in piglets, which is related to its promotion of intestinal epithelial integrity, microbial homeostasis and the production of short-chain fatty acids. In addition, dietary fatty acids and dietary electrolyte balance can also facilitate the growth, function and health of piglets by regulating intestinal epithelial function, immune system and microbiota. Thus, a targeted control of dietary components to promote the establishment of a healthy bacterial community is a significant method for preventing nutritional diarrhea in weaned piglets.

Dietary crude protein time-dependently modulates the bacterial community and metabolites and changes dietary nutrient efficiency in growing pigs

The reduced nutrient digestibility of low-protein (LP) diets has been shown to be caused by the weakened fermentative capacity of the post-gut flora. The dynamic regulation of dietary protein contents on post-gut microbial population and fermentative metabolism is unclear. Twelve growing barrows (19.9 ± 0.8 kg) fitted with a T-cannula at the blind end of the cecum were randomly administered a high-protein (HP, 21.5% crude protein [CP]) diet or an LP (15.5% CP) diet for 28 d. The cecal content and feces were collected at d 1, 14, and 28 of the experiment for microflora structures and metabolite concentrations analysis. The nutrient digestibility coefficient and plasma biochemical parameters were also determined. Compared with the HP treatment, the LP treatment showed decreased plasma urea nitrogen concentration and apparent total tract digestibility of dry matter, gross energy, and CP (P < 0.01). In addition, urinary nitrogen losses, total nitrogen losses, and daily nitrogen retention in the LP treatment were lower than those in the HP treatment (P < 0.01), and the nitrogen retention-to-nitrogen intake ratio in the LP treatment was increased (P < 0.01). The HP group showed increased cecal total short-chain fatty acids (SCFA) concentration and fecal propionate, butyrate, and total SCFA concentrations (P < 0.05) on d 14 and 28, which may be mainly related to the elevated abundance of SCFA-producing bacteria, such as Ruminococcus, Lactobacillus, and Prevotella (P < 0.05). Probiotics, such as Bifidobacterium, Bacteroidales S24-7, and Rikenella, enriched in the LP treatment possibly contributed to reduced plasma endotoxin content. The differences in the abundances of almost all the above-mentioned flora appeared on d 28 but not d 14. Likewise, differences in the Simpson and Shannon indices and clustering patterns of the microbiota between treatments were also only observed on d 28. To sum up, in a time-dependent manner, the LP diet increased probiotics with gut-improving functions and decreased SCFA-producing bacteria, which may cause enhanced intestine health and reduced nutrient digestibility.

Digestive dynamics: Unveiling interplay between the gut microbiota and the liver in macronutrient metabolism and hepatic metabolic health

Although the liver is the largest metabolic organ in the body, it is not alone in functionality and is assisted by "an organ inside an organ," the gut microbiota. This review attempts to shed light on the partnership between the liver and the gut microbiota in the metabolism of macronutrients (i.e., proteins, carbohydrates, and lipids). All nutrients absorbed by the small intestines are delivered to the liver for further metabolism. Undigested food that enters the colon is metabolized further by the gut microbiota that produces secondary metabolites, which are absorbed into portal circulation and reach the liver. These microbiota-derived metabolites and co-metabolites include ammonia, hydrogen sulfide, short-chain fatty acids, secondary bile acids, and trimethylamine N-oxide. Further, the liver produces several compounds, such as bile acids that can alter the gut microbial composition, which can in turn influence liver health. This review focuses on the metabolism of these microbiota metabolites and their influence on host physiology. Furthermore, the review briefly delineates the effect of the portosystemic shunt on the gut microbiota-liver axis, and current understanding of the treatments to target the gut microbiota-liver axis.

Dietary Strategies to Improve Exercise Performance by Modulating the Gut Microbiota

Numerous research studies have shown that moderate physical exercise exerts positive effects on gastrointestinal tract health and increases the variety and relative number of beneficial microorganisms in the intestinal microbiota. Increasingly, studies have shown that the gut microbiota is critical for energy metabolism, immunological response, oxidative stress, skeletal muscle metabolism, and the regulation of the neuroendocrine system, which are significant for the physiological function of exercise. Dietary modulation targeting the gut microbiota is an effective prescription for improving exercise performance and alleviating exercise fatigue. This article discusses the connection between exercise and the makeup of the gut microbiota, as well as the detrimental effects of excessive exercise on gut health. Herein, we elaborate on the possible mechanism of the gut microbiota in improving exercise performance, which involves enhancing skeletal muscle function, reducing oxidative stress, and regulating the neuroendocrine system. The effects of dietary nutrition strategies and probiotic supplementation on exercise from the perspective of the gut microbiota are also discussed in this paper. A deeper understanding of the potential mechanism by which the gut microbiota exerts positive effects on exercise and dietary nutrition recommendations targeting the gut microbiota is significant for improving exercise performance. However, further investigation is required to fully comprehend the intricate mechanisms at work.

Assessment of the relationship between gut microbiota and bone mineral density: a two-sample Mendelian randomization study

Background

Emerging evidence from observational studies and clinical trials suggests a connection between the gut microbiota and variations in bone mineral density (BMD). Nonetheless, the specific association between gut microbiota and BMD alterations at different skeletal sites has not been comprehensively explored. To address this, we employed Genome-Wide Association Study (GWAS) summary statistics from a publicly accessible database, conducting a two-sample Mendelian Randomization analysis to elucidate the potential causal relationship between gut microbiota composition and BMD.

Methods

This study utilized two distinct thresholds for screening instrumental variables (IVs), followed by an extensive series of quality control procedures to identify IVs that were significantly related to exposure. Gut microbiota were classified into two sets based on hierarchical levels: phylum, class, order, family, and genus. Bone mineral density (BMD) data were systematically collected from four skeletal sites: femoral neck, lumbar spine, forearm, and heel. For Mendelian Randomization (MR) analysis, robust methods including Inverse-Variance Weighting (IVW) and the Wald Ratio Test were employed. Additional analytical tests such as the Outlier Test, Heterogeneity Test, 'Leave-One-Out' Test, and Pleiotropy Test were conducted to assess the impact of horizontal pleiotropy, heterogeneities, and the genetic variation stability of gut microbiota on BMD causal associations. The MR Steiger Directionality Test was applied to exclude studies with potential directional biases.

Results

In this two-sample Mendelian randomization analysis, we utilized five sets of exposure GWAS (Genome-Wide Association Studies) summary statistics and four sets of outcome GWAS summary statistics. The initial analysis, applying a threshold of p < 5 × 10-6, identified 48 significant causal relationships between genetic liability in the gut microbiome and bone mineral density (BMD). A subsequent analysis with a more stringent threshold of p < 5 × 10-8 uncovered 14 additional causal relationships. Upon applying the Bonferroni correction, 9 results from the first analysis and 10 from the second remained statistically significant.

Conclusion

Our MR analysis revealed a causal relationship between gut microbiota and bone mineral density at all sites, which could lead to discoveries in future mechanistic and clinical studies of microbiota-associated osteoporosis.

Effects of Eimeria acervulina infection on the luminal and mucosal microbiota of the cecum and ileum in broiler chickens

Coccidiosis, an intestinal disease caused by Eimeria parasites, is responsible for major losses in the poultry industry by impacting chicken health. The gut microbiota is associated with health factors, such as nutrient exchange and immune system modulation, requiring understanding on the effects of Eimeria infection on the gut microbiota. This study aimed to determine the effects of Eimeria acervulina infection on the luminal and mucosal microbiota of the cecum (CeL and CeM) and ileum (IlL and IlM) at multiple time points (days 3, 5, 7, 10, and 14) post-infection. E. acervulina infection decreased evenness in CeL microbiota at day 10, increased richness in CeM microbiota at day 3 before decreasing richness at day 14, and decreased richness in IlL microbiota from day 3 to 10. CeL, CeM, and IlL microbiota differed between infected and control birds based on beta diversity at varying time points. Infection reduced relative abundance of bacterial taxa and some predicted metabolic pathways known for short-chain fatty acid production in CeL, CeM, and IlL microbiota, but further understanding of metabolic function is required. Despite E. acervulina primarily targeting the duodenum, our findings demonstrate the infection can impact bacterial diversity and abundance in the cecal and ileal microbiota.

Gastrointestinal microbiota-directed nutritional and therapeutic interventions for inflammatory bowel disease: opportunities and challenges

Evidence-based research has confirmed the role of gastrointestinal microbiota in regulating intestinal inflammation. These data have generated interest in developing microbiota-based therapies for the prevention and management of inflammatory bowel disease (IBD). Despite in-depth understanding of the etiology of IBD, it currently lacks a cure and requires ongoing management. Accumulating data suggest that an aberrant gastrointestinal microbiome, often referred to as dysbiosis, is a significant environmental instigator of IBD. Novel microbiome-targeted interventions including prebiotics, probiotics, fecal microbiota transplant, and small molecule microbiome modulators are being evaluated as therapeutic interventions to attenuate intestinal inflammation by restoring a healthy microbiota composition and function. In this review, the effectiveness and challenges of microbiome-centered interventions that have the potential to alleviate intestinal inflammation and improve clinical outcomes of IBD are explored.

Butyrate and iso-butyrate: a new perspective on nutrition prevention of gestational diabetes mellitus

BACKGROUND

Dietary imbalance, such as a lower proportion of complex carbohydrates and a higher protein diet, may contribute to gestational diabetes mellitus (GDM) risks through their metabolisms. However, there is a lack of knowledge regarding the association between butyrate, iso-butyrate, and GDM, which are metabolisms of the two primary nutrients above. This study aimed to clarify the association of butyrate and iso-butyrate with GDM.

METHODS

A nested case-control study was conducted based on the Beijing Birth Cohort Study (BBCS) from 2017 to 2018. Totally, 99 singleton women were involved (GDM: n = 49, control: n = 50). All participants provided blood samples twice (in their first and second trimesters). Gas chromatography-mass spectrometry (GC-MS) was used for butyrate and iso-butyrate detection. Unconditional logistic regression and receiver operating characteristic (ROC) curve analysis were used for statistical analysis.

RESULTS

The results showed that butyrate in the first trimester was negatively correlated with GDM (odds ratio (OR): 0.00, 95% confidential interval (CI): 0.00-0.21, P = 0.008), and iso-butyrate in the second trimester was positively related to GDM (OR: 627.68, 95% CI: 40.51-9724.56, P < 0.001). The ratio (butyrate/iso-butyrate) was negatively associated with GDM, both in the first trimester (OR: 0.00, 95%CI: 0.00-0.05, P < 0.001) and in the second trimester (OR: 0.52, 95% CI: 0.34-0.80, P = 0.003). The area under the curve (AUC) using the ratio in the first trimester combined with clinical risk factors achieved 0.89 (95% CI: 0.83-0.95). Iso-butyrate in the second trimester combined with clinical risk factors achieved an AUC of 0.97 (95% CI: 0.92-1.00).

CONCLUSIONS

High iso-butyrate and low butyrate levels may be associated with an increased risk of GDM. As they are produced through dietary nutrient formation by gut microbiota, further studies on the association of dietary intake and butyrate or iso-butyrate concentration in plasma may help find a novel approach to nutritional intervention for GDM.

Unveiling the breadmaking transformation: Structural and functional insights into Arabinoxylan

To understand the changes in arabinoxylan (AX) during breadmaking, multi-step enzyme digestion was conducted to re-extract arabinoxylan (AX-B) from AX-fortified bread. Their structural changes were compared using HPSEC, HPAEC, FT-IR, methylation analysis, and 1H NMR analysis; their properties changes in terms of enzymatic inhibition activities and in vitro fermentability against gut microbiota were also compared. Results showed that AX-B contained a higher portion of covalently linked protein while the molecular weight was reduced significantly after breadmaking process (from 677.1 kDa to 15.6 kDa); the structural complexity of AX-B in terms of the degree of branching was increased; the inhibition activity against α-amylase (76.81 % vs 73.89 % at 4 mg/mL) and α-glucosidase (64.43 % vs 58.08 % at 4 mg/mL) was improved; the AX-B group produced a higher short-chain fatty acids concentration than AX (54.68 ± 7.86 mmol/L vs 44.03 ± 4.10 mmol/L). This study provides novel knowledge regarding the structural and properties changes of arabinoxylan throughout breadmaking, which help to predict the health benefits of fibre-fortified bread and achieve precision nutrition.

In Vitro Fermentation Shows Polyphenol and Fiber Blends Have an Additive Beneficial Effect on Gut Microbiota States

Polyphenols and fermentable fibers have shown favorable effects on gut microbiota composition and metabolic function. However, few studies have investigated whether combining multiple fermentable fibers or polyphenols may have additive beneficial effects on gut microbial states. Here, an in vitro fermentation model, seeded with human stool combined from 30 healthy volunteers, was supplemented with blends of polyphenols (PP), dietary fibers (FB), or their combination (PPFB) to determine influence on gut bacteria growth dynamics and select metabolite changes. PP and FB blends independently led to significant increases in the absolute abundance of select beneficial taxa, namely Ruminococcus bromii, Bifidobacterium spp., Lactobacillus spp., and Dorea spp. Total short-chain fatty acid concentrations, relative to non-supplemented control (F), increased significantly with PPFB and FB supplementation but not PP. Indole and ammonia concentrations decreased with FB and PPFB supplementation but not PP alone while increased antioxidant capacity was only evident with both PP and PPFB supplementation. These findings demonstrated that, while the independent blends displayed selective positive impacts on gut states, the combination of both blends provided an additive effect. The work outlines the potential of mixed substrate blends to elicit a broader positive influence on gut microbial composition and function to build resiliency toward dysbiosis.

A Free Amino Acid Diet Alleviates Colorectal Tumorigenesis through Modulating Gut Microbiota and Metabolites

Colorectal cancer (CRC), a major global health concern, may be influenced by dietary protein digestibility impacting gut microbiota and metabolites, which is crucial for cancer therapy effectiveness. This study explored the effects of a casein protein diet (CTL) versus a free amino acid (FAA)-based diet on CRC progression, gut microbiota, and metabolites using carcinogen-induced (AOM/DSS) and spontaneous genetically induced (ApcMin/+ mice) CRC mouse models. Comprehensive approaches including 16s rRNA gene sequencing, transcriptomics, metabolomics, and immunohistochemistry were utilized. We found that the FAA significantly attenuated CRC progression, evidenced by reduced colonic shortening and histopathological alterations compared to the CTL diet. Notably, the FAA enriched beneficial gut bacteria like Akkermansia and Bacteroides and reversed CRC-associated dysbiosis. Metabolomic analysis highlighted an increase in ornithine cycle metabolites and specific fatty acids, such as Docosapentaenoic acid (DPA), in FAA-fed mice. Transcriptomic analysis revealed that FAA up-regulated Egl-9 family hypoxia inducible factor 3 (Egln 3) and downregulated several cancer-associated pathways including Hippo, mTOR, and Wnt signaling. Additionally, DPA was found to significantly induce EGLN 3 expression in CRC cell lines. These results suggest that FAA modulate gut microbial composition, enhance protective metabolites, improve gut barrier functions, and inhibit carcinogenic pathways.

In vitro batch fermentation of (un)saturated homogalacturonan oligosaccharides

Pectin, predominantly present within plant cell walls, is a dietary fiber that potentially induces distinct health effects depending on its molecular structure. Such structure-dependent health effects of pectin-derived galacturonic acid oligosaccharides (GalA-OS) are yet largely unknown. This study describes the influence of methyl-esterification and ∆4,5-unsaturation of GalA-OS through defined sets of GalA-OS made from pectin using defined pectinases, on the fermentability by individual fecal inocula. The metabolite production, OS utilization, quantity and size, methyl-esterification and saturation of remaining GalA-OS were monitored during the fermentation of GalA-OS. Fermentation of all GalA-OS predominantly induced the production of acetate, butyrate and propionate. Metabolization of unsaturated GalA-OS (uGalA-OS) significantly increased butyrate formation compared to saturated GalA-OS (satGalA-OS), while satGalA-OS significantly increased propionate formation. Absence of methyl-esters within GalA-OS improved substrate metabolization during the first 18 h of fermentation (99 %) compared to their esterified analogues (51 %). Furthermore, HPAEC and HILIC-LC-MS revealed accumulation of specific methyl-esterified GalA-OS, confirming that methyl-esterification delays fermentation. Fermentation of structurally distinct GalA-OS results in donor specific microbiota composition with uGalA-OS specifically stimulating the butyrate-producer Clostridium Butyricum. This study concludes that GalA-OS fermentation induces highly structure-dependent changes in the gut microbiota, further expanding their potential use as prebiotics.

Bacteroides and NAFLD: pathophysiology and therapy

Non-alcoholic fatty liver disease (NAFLD) is a prevalent chronic liver condition observed globally, with the potential to progress to non-alcoholic steatohepatitis (NASH), cirrhosis, and even hepatocellular carcinoma. Currently, the US Food and Drug Administration (FDA) has not approved any drugs for the treatment of NAFLD. NAFLD is characterized by histopathological abnormalities in the liver, such as lipid accumulation, steatosis, hepatic balloon degeneration, and inflammation. Dysbiosis of the gut microbiota and its metabolites significantly contribute to the initiation and advancement of NAFLD. Bacteroides, a potential probiotic, has shown strong potential in preventing the onset and progression of NAFLD. However, the precise mechanism by which Bacteroides treats NAFLD remains uncertain. In this review, we explore the current understanding of the role of Bacteroides and its metabolites in the treatment of NAFLD, focusing on their ability to reduce liver inflammation, mitigate hepatic steatosis, and enhance intestinal barrier function. Additionally, we summarize how Bacteroides alleviates pathological changes by restoring the metabolism, improving insulin resistance, regulating cytokines, and promoting tight-junctions. A deeper comprehension of the mechanisms through which Bacteroides is involved in the pathogenesis of NAFLD should aid the development of innovative drugs targeting NAFLD.

Protein combined with certain dietary fibers increases butyrate production in gut microbiota fermentation

The modern diet delivers nearly equal amounts of carbohydrates and protein into the colon representing an important protein increase compared to past higher fiber diets. At the same time, plant-based protein foods have become increasingly popular, and these sources of protein are generally less digestible than animal protein sources. As a result, a significant amount of protein is expected to reach the colon and be available for fermentation by gut microbiota. While studies on diet-microbiota interventions have mainly focused on carbohydrate fermentation, limited attention has been given to the role of protein or protein-fiber mixtures as fermentation substrates for the colonic microbiota. In this study, we aimed to investigate: (1) how changing the ratio of protein to fiber substrates affects the types and quantities of gut microbial metabolites and bacteria; and (2) how the specific fermentation characteristics of different types of fiber might influence the utilization of protein by gut microbes to produce beneficial short chain fatty acids. Our results revealed that protein fermentation in the gut plays a crucial role in shaping the overall composition of microbiota communities and their metabolic outputs. Surprisingly, butyrate production was maintained or increased when fiber and protein were combined, and even when pure protein samples were used as substrates. These findings suggest that indigestible protein in fiber-rich substrates may promote the production of microbial butyrate perhaps including the later stages of fermentation in the large intestine.

How important is food structure when cats eat mice?

Feeding whole prey to felids has shown to benefit their gastrointestinal health. Whether this effect is caused by the chemical or physical nature of whole prey is unknown. Fifteen domestic cats, as a model for strict carnivores, were either fed minced mice (MM) or whole mice (WM), to determine the effect of food structure on digestibility, mean urinary excretion time (MUET) of 15N, intestinal microbial activity and fermentation products. Faeces samples were collected after feeding all cats a commercially available extruded diet (EXT) for 10 d before feeding for 19 d the MM and WM diets with faeces and urine collected from day 11 to 15. Samples for microbiota composition and determination of MUET were obtained from day 16 to 19. The physical structure of the mice diet (minced or not) did not affect large intestinal fermentation as total SCFA and branched-chain fatty acid (BCFA), and most biogenic amine (BA) concentrations were not different (P > 0·10). When changing from EXT to the mice diets, the microbial community composition shifted from a carbolytic (Prevotellaceae) to proteolytic (Fusobacteriaceae) profile and led to a reduced faecal acetic to propionic acid ratio, SCFA, total BCFA (P < 0·001), NH3 (P = 0·04), total BA (P < 0·001) and para-cresol (P = 0·08). The results of this study indicate that food structure within a whole-prey diet is less important than the overall diet type, with major shifts in microbiome and decrease in potentially harmful fermentation products when diet changes from extruded to mice. This urges for careful consideration of the consequences of prey-based diets for gut health in cats.

Effect of nutmeg essential oil (Myristica fragrans Houtt.) on methane production, rumen fermentation, and nutrient digestibility in vitro

The study evaluated the effect of adding of nutmeg (Myristica fragrans Houtt.) essential oil (NEO) as a feed additive on methane production, rumen fermentation parameters, rumen enzyme activity, and nutrient digestibility in vitro. This study was divided into three treatments based on the level of NEO addition, which included 0 µL/L (T0), 100 µL/L (T1), and 200 µL/L (T2). The feed substrate composition consisted of king grass as forage and concentrate in a 60:40 ratio. Feed fermentation was conducted using the Menke and Steingass gas production and two-step Tilley and Terry in-vitro digestibility technique. The data obtained from the study were analyzed using one-way ANOVA and if there were differences between means, they were further assessed using DMRT. The results showed that T2 treatment significantly decreased (P < 0.05) ammonia (NH3) levels, total VFA, acetate, propionate, butyrate, and microbial protein (P < 0.05). Methane production and the activity of rumen protease enzyme significantly decreased (P < 0.05) at T1 and T2 treatment. The T2 treatment significantly reduced (P < 0.05) protein digestibility (IVCPD) at 48 h, while IVCPD at 96 h significantly increased (P < 0.05). On the other hand, the addition of nutmeg essential oil did not effect the activity of the amylase, carboxymethyl cellulase, and β-glucosidase enzymes, as well as the in-vitro digestibility of dry matter (IVDMD), crude fiber (IVCFD), and organic matter (IVOMD). The conclusion drawn from this study is that the optimum level for NEO is 200 µL/L, which can reduce methane production and increase crude protein digestibility at 96 h without any negative effect on rumen fermentation and nutrient digestibility.

Impact of synbiotics on growth performance and gut health in Murrah buffalo calves

Synbiotics have been used as biotherapeutic supplements for prevention of new-born calf gastrointestinal disorders. Present study was conducted to evaluate the impact of fructo-oligosaccharide, mannan-oligosaccharide and inulin along with Lactobacillus plantarum CRD-7 and Lactobacillus acidophilus NCDC15 on the nutrient digestibility, growth performance and faecal microbial population of pre-ruminant buffalo calves. Twenty-four Murrah calves (5 days old) were randomly assigned to four groups of six calves in each using randomized block design. Calves in Group I (control) received only a basic diet of milk, calf starter and berseem with no additives. Calves in Group II (SYN1) were fed 6 g fructo-oligosaccharide (FOS) + Lactobacillus plantarum CRD-7 (100 ml). Calves in Group III (SYN2) were fed 9 g inulin + L. plantarum CRD-7 (50 ml), while calves in Group IV (SYN3) received 4 g MOS + L. acidophilus NCDC15 (200 ml) as fermented milk having 108 CFU/ml/calf/day in addition to the basal diet. The results revealed that digestibility of dry matter, crude protein, ether extract and average daily gain were all higher (P < 0.05) in SYN1 as compared to control group. The antioxidant enzyme activity, humoral and cell mediated immunity performed well in SYN1, SYN2 and SYN3 as compared to control. Diarrhoea and faecal scouring were lower (P < 0.05) in all supplemented groups than control. Faecal Lactobacilli and Bifidobacterium counts were also higher in SYN1 group followed by SYN2 and SYN3. Faecal ammonia, lactate, pH, and volatile fatty acids level were increased in SYN1 supplemented groups. The synbiotic combination of 6 g FOS + L. plantarum CRD-7 had better response on digestibility, average daily gain, antioxidant enzymes, immune response, faecal microbiota and metabolites and also reduce the faecal score and diarrhoea incidence. Therefore, supplementation of 6 g FOS + L. plantarum CRD-7 can be advised for general use in order to promote long-term animal production.

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.

Gastric clot formation and digestion of milk proteins in static in vitro infant gastric digestion models representing different ages

Gastric digestion conditions change during infancy from newborn towards more adult digestion conditions, which can change gastric digestion kinetics. However, how these changes in gastric digestion conditions during infancy affect milk protein digestion has not been investigated. Therefore, we aimed to investigate milk protein digestion with static in vitro gastric digestion models representing one-, three- and six-month-old infants. With increasing age, gastric clots and soluble proteins were digested more extensively, which may partly be attributed to the looser gastric clot structure. Larger differences with increasing age were found for heated than unheated milk proteins, which might be caused by the presence of denatured whey proteins. Taken together, these findings show that gastric milk protein digestion increases during infancy. These in vitro gastric digestion models could be used to study how milk protein digestion changes with infant age, which may aid in developing infant formulas for different age stages.

Faecal Bacteriome and Metabolome Profiles Associated with Decreased Mucosal Inflammatory Activity Upon Anti-TNF Therapy in Paediatric Crohn's Disease

BACKGROUND AND AIMS

Treatment with anti-tumour necrosis factor α antibodies [anti-TNF] changes the dysbiotic faecal bacteriome in Crohn's disease [CD]. However, it is not known whether these changes are due to decreasing mucosal inflammatory activity or whether similar bacteriome reactions might be observed in gut-healthy subjects. Therefore, we explored changes in the faecal bacteriome and metabolome upon anti-TNF administration [and therapeutic response] in children with CD and contrasted those to anti-TNF-treated children with juvenile idiopathic arthritis [JIA].

METHODS

Faecal samples collected longitudinally before and during anti-TNF therapy were analysed with regard to the bacteriome by massively parallel sequencing of the 16S rDNA [V4 region] and the faecal metabolome by 1H nuclear magnetic resonance imaging. The response to treatment by mucosal healing was assessed by the MINI index at 3 months after the treatment started. We also tested several representative gut bacterial strains for in vitro growth inhibition by infliximab.

RESULTS

We analysed 530 stool samples from 121 children [CD 54, JIA 18, healthy 49]. Bacterial community composition changed on anti-TNF in CD: three members of the class Clostridia increased on anti-TNF, whereas the class Bacteroidia decreased. Among faecal metabolites, glucose and glycerol increased, whereas isoleucine and uracil decreased. Some of these changes differed by treatment response [mucosal healing] after anti-TNF. No significant changes in the bacteriome or metabolome were noted upon anti-TNF in JIA. Bacterial growth was not affected by infliximab in a disc diffusion test.

CONCLUSIONS

Our findings suggest that gut mucosal healing is responsible for the bacteriome and metabolome changes observed in CD, rather than any general effect of anti-TNF.

Unraveling the gut health puzzle: exploring the mechanisms of butyrate and the potential of High-Amylose Maize Starch Butyrate (HAMSB) in alleviating colorectal disturbances

Colorectal disturbances encompass a variety of disorders that impact the colon and rectum, such as colitis and colon cancer. Butyrate, a short-chain fatty acid, plays a pivotal role in supporting gut health by nourishing colonocytes, promoting barrier function, modulating inflammation, and fostering a balanced microbiome. Increasing colorectal butyrate concentration may serve as a critical strategy to improve colon function and reduce the risk of colorectal disturbances. Butyrylated high-amylose maize starch (HAMSB) is an edible ingredient that efficiently delivers butyrate to the colon. HAMSB is developed by esterifying a high-amylose starch backbone with butyric anhydride. With a degree of substitution of 0.25, each hydroxy group of HAMSB is substituted by a butyryl group in every four D-glucopyranosyl units. In humans, the digestibility of HAMSB is 68% (w/w), and 60% butyrate molecules attached to the starch backbone is absorbed by the colon. One clinical trial yielded two publications, which showed that HAMSB significantly reduced rectal O6-methyl-guanine adducts and epithelial proliferation induced by the high protein diet. Fecal microbial profiles were assessed in three clinical trials, showing that HAMSB supplementation was consistently linked to increased abundance of Parabacteroides distasonis. In animal studies, HAMSB was effective in reducing the risk of diet- or AOM-induced colon cancer by reducing genetic damage, but the mechanisms differed. HAMSB functioned through affecting cecal ammonia levels by modulating colon pH in diet-induced cancer, while it ameliorated chemical-induced colon cancer through downregulating miR19b and miR92a expressions and subsequently activating the caspase-dependent apoptosis. Furthermore, animal studies showed that HAMSB improved colitis via regulating the gut immune modulation by inhibiting histone deacetylase and activating G protein-coupled receptors, but its role in bacteria-induced colon colitis requires further investigation. In conclusion, HAMSB is a food ingredient that may deliver butyrate to the colon to support colon health. Further clinical trials are warranted to validate earlier findings and determine the minimum effective dose of HAMSB.

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.

Investigating the effects of ultrafine bubbles on bacterial growth

Several previous studies have considered ultrafine bubbles as a potential research target because their properties can be applied in many different research areas. In particular, the interaction between UFBs and microorganisms has always been one of the aspects that receives much attention due to the high difficulty in controlling a living system. The properties of UFBs, as mobile air-water interfaces, are greatly determined by their gas cores which play a critical role in regulating microbial growth. This study aims to investigate the effects of ultrafine bubbles on bacterial growth. Two well-studied organisms were chosen as models - Escherichia coli and Staphylococcus aureus. Their growing behavior was examined based on the growth rate, phenotype and biomass. Three types of Luria-Bertani cultures were tested, including a standard culture containing distilled water, an air ultrafine bubble culture, and a hydrogen ultrafine bubble culture. The UFBs were generated via ultrasonic cavitation and stabilized by 50 μM SDS, which was proven to have negligible effects on bacterial growth. By comparing among the three cultivation conditions, the bacterial growth rates were observed to be the highest in exposure to HUFBs. The results also signified that UFBs had an enhancement on cell proliferation. On the other hand, while proposing an increase in cell density, bacteria cultured in HUFB media have their sizes decreased uniformly and significantly (p-value < 0.05). This study confirmed that bacterial growth was promoted by UFBs; and better effects recorded were due to the HUFB present in the culture media. However, the average morphological size of bacteria was in negative correlation with their population size.

Dietary Milk or Isolated Legume Proteins Modulate Intestinal Microbiota Composition in Rats

Shifts toward increased proteolytic fermentation, such as, for example, in athlete and high-protein weight loss diets, may alter the relative abundance of microbial species in the gut and generate bioactive, potentially deleterious metabolic products. In the current investigation, intestinal (caecal) microbiota composition was studied in rats fed diets differing only in their constituent proteins: milk (casein (CAS), lactalbumin (LA)) or legume (Cicer arietinum, Lupinus angustifolius) protein isolates (chickpea protein isolate (CPI), lupin protein isolate (LI)). ANOSIM and Discriminant Analysis showed significant (p < 0.05) differences at both family and genus levels in both microbiota composition and functionality as a consequence of feeding the different proteins. Differences were also significant (p < 0.05) for predicted functionality parameters as determined by PICRUSt analysis. LA induced a generally healthier microbiota composition than CAS, and higher amounts of Methanobrevibacter spp. and Methanogenic_PWY were found in the LI group. LEfSe analysis of bacterial composition and functional activities revealed a number of groups/functions able to explain the different effects found with milk and legume protein isolates. In conclusion, the mostly beneficial modulation of intestinal microbiota generally found with legume-based diets is likely to be due, at least in part, to their constituent proteins.

Lentils protein isolate as a fermenting substrate for the production of bioactive peptides by lactic acid bacteria and neglected yeast species

In the current trend where plant-based foods are preferred over animal-based foods, pulses represent an alternative source of protein but also of bioactive peptides (BPs). We investigated the pattern of protein hydrolysis during fermentation of red lentils protein isolate (RLPI) with various lactic acid bacteria and yeast strains. Hanseniaspora uvarum SY1 and Fructilactobacillus sanfranciscensis E10 were the most proteolytic microorganisms. H. uvarum SY1 led to the highest antiradical, angiotensin-converting enzyme-inhibitory and antifungal activities, as found in low molecular weight water soluble extracts (LMW-WSE). The 2039 peptide sequences identified by LMW-WSE were screened using BIOPEP UWM database, and 36 sequences matched with known BPs. Fermentation of RLPI by lactic acid bacteria and yeasts generated 12 peptides undetected in raw RLPI. Besides, H. uvarum SY1 led to the highest abundance (peak areas) of BPs, in particular with antioxidant and ACE-inhibitory activities. The amino acid sequences LVR and LVL, identified in the fermented RLPI, represent novel findings, as they were detected for the first time in substrates subjected to microbial fermentation. KVI, another BP highly characteristic of RLPI-SY1, was previously observed only in dried bonito. 44 novel potential BPs, worthy of further characterization, were correlated with antifungal activity.

Dietary Amino Acid Source Elicits Sex-Specific Metabolic Response to Diet-Induced NAFLD in Mice

SCOPE

Non-alcoholic fatty liver disease (NAFLD) is a sexually dimorphic disease influenced by dietary factors. Here, the metabolic and hepatic effects of dietary amino acid (AA) source is assessed in Western diet (WD)-induced NAFLD in male and female mice.

METHODS AND RESULTS

The AA source is either casein or a free AA mixture mimicking the composition of casein. As expected, males fed a casein-based WD display glucose intolerance, fasting hyperglycemia, and insulin-resistance and develop NAFLD associated with changes in hepatic gene expression and microbiota dysbiosis. In contrast, males fed the AA-based WD show no steatosis, a similar gene expression profile as males fed a control diet, and a distinct microbiota composition compared to males fed a casein-based WD. Females are protected against WD-induced liver damage, hepatic gene expression, and gut microbiota changes regardless of the AA source.

CONCLUSIONS

Free dietary AA intake prevents the unhealthy metabolic outcomes of a WD preferentially in male mice.

Diet-microbiota associations in gastrointestinal research: a systematic review

Interactions between diet and gastrointestinal microbiota influence health status and outcomes. Evaluating these relationships requires accurate quantification of dietary variables relevant to microbial metabolism, however current dietary assessment methods focus on dietary components relevant to human digestion only. The aim of this study was to synthesize research on foods and nutrients that influence human gut microbiota and thereby identify knowledge gaps to inform dietary assessment advancements toward better understanding of diet-microbiota interactions. Thirty-eight systematic reviews and 106 primary studies reported on human diet-microbiota associations. Dietary factors altering colonic microbiota included dietary patterns, macronutrients, micronutrients, bioactive compounds, and food additives. Reported diet-microbiota associations were dominated by routinely analyzed nutrients, which are absorbed from the small intestine but analyzed for correlation to stool microbiota. Dietary derived microbiota-relevant nutrients are more challenging to quantify and underrepresented in included studies. This evidence synthesis highlights advancements needed, including opportunities for expansion of food composition databases to include microbiota-relevant data, particularly for human intervention studies. These advances in dietary assessment methodology will facilitate translation of microbiota-specific nutrition therapy to practice.

Optimizing the Gut Microbiota for Individualized Performance Development in Elite Athletes

The human gut microbiota can be compared to a fingerprint due to its uniqueness, hosting trillions of living organisms. Taking a sport-centric perspective, the gut microbiota might represent a physiological system that relates to health aspects as well as individualized performance in athletes. The athletes' physiology has adapted to their exceptional lifestyle over the years, including the diversity and taxonomy of the microbiota. The gut microbiota is influenced by several physiological parameters and requires a highly individual and complex approach to unravel the linkage between performance and the microbial community. This approach has been taken in this review, highlighting the functions that the microbial community performs in sports, naming gut-centered targets, and aiming for both a healthy and sustainable athlete and performance development. With this article, we try to consider whether initiating a microbiota analysis is practicable and could add value in elite sport, and what possibilities it holds when influenced through a variety of interventions. The aim is to support enabling a well-rounded and sustainable athlete and establish a new methodology in elite sport.

Effect of Cyberlindnera jadinii yeast on growth performance, nutrient digestibility, and gut health of broiler chickens from 1 to 34 d of age

The effect of dietary graded levels of Cyberlindnera jadinii yeast (C. jadinii) on growth performance, nutrient digestibility, and gut health of broilers was evaluated from 1 to 34 d of age. A total of 360 male broiler chicks were randomly allocated to 1 of 4 dietary treatments (6 replicate pens each) consisting of a wheat-soybean meal-based pelleted diet (Control or CJ0), and 3 diets in which 10% (CJ10), 20% (CJ20), and 30% (CJ30) of the crude protein were supplied by C. jadinii, by gradually replacing protein-rich ingredients. Body weight and feed intake were measured at d 1, 11, 22, and 32. Pellet temperature, durability, and hardness increased linearly (P < 0.05) with C. jadinii inclusion, with highest (P < 0.05) values for CJ30. Up until d 22, feed conversion ratio (FCR) was similar between treatments (P = 0.169). Overall, increasing C. jadinii inclusion linearly increased (P = 0.047) feed intake but had no effect on weight gain or mortality. FCR increased (P < 0.05) linearly with increasing C. jadinii inclusion but only birds fed CJ30 had a significantly poorer FCR compared to the Control. Ileal digestibility was not affected by C. jadinii inclusion, however, there was a significant linear decrease in crude protein and phosphorus, and a tendency for a decrease in fat digestibility. Apparent metabolizable energy (AME) decreased (P < 0.001) quadratically with increasing C. jadinii and was significantly lower in CJ30 compared to the Control. Ileal concentrations of volatile fatty acids (VFAs) were not affected by C. jadinii inclusion, but butyric acid and total VFAs were linearly and quadratically increased and were significantly higher in cecal digesta of birds fed CJ20 and CJ30. Increasing C. jadinii inclusion was associated with an increase (P < 0.05) in the relative abundance of lactobacillus in the ileum and cecum. In conclusion, C. jadinii yeast can supply up to 20% of the total dietary protein without negatively affecting performance, digestibility, or gut health of broilers. The potential confounding role of feed processing and C. jadinii cell wall components on broiler performance is discussed.

Tutorial on statistical data reduction methods for exploring dietary patterns

Diet is one of the most important factors affecting human health and it is different for each person. Examining individual foods in the diet does not provide sufficient information to the researcher, so we need food patterns to obtain more complete information. Food pattern analysis is also a complementary approach that is carried out by statistical methods and provides additional evidence in this regard. In this tutorial article, we have tried to briefly explain all statistical analyses which can used for dietary pattern analysis.

The association of the healthy eating index with risk of colorectal cancers (overall and by subsite) among Canadians

BACKGROUND

Healthy dietary patterns characterized by high intake of fruits and vegetables, grains/cereals, and lean meat/fish, and low intake of red/processed meats and refined carbohydrates, have been shown to be associated with reduced risk of colorectal cancer, but evidence regarding their association with colorectal cancer subsites is limited. Hence, this study was conducted to assess the association of a healthy dietary pattern, as reflected in the Healthy Eating Index (HEI) (a composite score based on consumption of various food groups), with risk of colorectal cancer, overall and by subsite.

METHODS

We conducted a case-cohort study in the Canadian Study of Diet, Lifestyle and Health (CSDLH). The study included all cases of incident colorectal cancer in the entire cohort, and an age-stratified subcohort of 3185 women and 2622 men. Cox regression models were used to estimate hazard ratios (HR) for the association between the HEI and the risk of colorectal cancer, overall and by subsite. We also assessed the association by sex and by selected metabolic factors.

RESULTS

For both sexes combined, the highest quintile of the HEI score was inversely associated with risk of colorectal cancer, colon cancer and proximal colon cancer (HR: 0.65; 95% CI: 0. 49-0.85, HR: 0.60, 95% CI: 0.44-0.83 and HR: 0.54, 95% CI: 0.35-0.85, respectively). However, these associations were mostly observed among men (HR: 0.56; 95% CI: 0.38-0.81, HR: 0.44, 95% CI: 0.28-0.69 and HR: 0.26; 95% CI: 0.12-0.56, for colorectal cancer, colon cancer and proximal colon cancer, respectively; p-interactions=0.029, 0.032 and 0.063, respectively). An inverse association was also observed between the HEI and risk of colorectal cancer among normal weight participants, overweight/obese participants, non-smokers, non-alcohol drinkers and participants who were physically inactive.

CONCLUSION

A healthy dietary pattern may reduce risk of colorectal cancer, particularly among men.

Arabinoxylan source and xylanase specificity influence the production of oligosaccharides with prebiotic potential

Cereal arabinoxylans (AXs) are complex polysaccharides in terms of their pattern of arabinose and ferulic acid substitutions, which influence their properties in structural and nutritional applications. We have evaluated the influence of the molecular structure of three AXs from wheat and rye with distinct substitutions on the activity of β-xylanases from different glycosyl hydrolase families (GH 5_34, 8, 10 and 11). The arabinose and ferulic acid substitutions influence the accessibility of the xylanases, resulting in specific profiles of arabinoxylan-oligosaccharides (AXOS). The GH10 xylanase from Aspergillus aculeatus (AcXyn10A) and GH11 from Thermomyces lanuginosus (TlXyn11) showed the highest activity, producing larger amounts of small oligosaccharides in shorter time. The GH8 xylanase from Bacillus sp. (BXyn8) produced linear xylooligosaccharides and was most restricted by arabinose substitution, whereas GH5_34 from Gonapodya prolifera (GpXyn5_34) required arabinose substitution and produced longer (A)XOS substituted on the reducing end. The complementary substrate specificity of BXyn8 and GpXyn5_34 revealed how arabinoses were distributed along the xylan backbones. This study demonstrates that AX source and xylanase specificity influence the production of oligosaccharides with specific structures, which in turn impacts the growth of specific bacteria (Bacteroides ovatus and Bifidobacterium adolescentis) and the production of beneficial metabolites (short-chain fatty acids).

Diversity of the microbiota communities found in the various regions of the intestinal tract in healthy individuals and inflammatory bowel diseases

The severe and chronic inflammatory bowel diseases (IBD), Crohn disease and ulcerative colitis, are characterized by persistent inflammation and gut damage. There is an increasing recognition that the gut microbiota plays a pivotal role in IBD development and progression. However, studies of the complete microbiota composition (bacteria, fungi, viruses) from precise locations within the gut remain limited. In particular, studies have focused primarily on the bacteriome, with available methods limiting evaluation of the mycobiome (fungi) and virome (virus). Furthermore, while the different segments of the small and large intestine display different functions (e.g., digestion, absorption, fermentation) and varying microenvironment features (e.g., pH, metabolites), little is known about the biogeography of the microbiota in different segments of the intestinal tract or how this differs in IBD. Here, we highlight evidence of the differing microbiota communities of the intestinal sub-organs in healthy and IBD, along with method summaries to improve future studies.

Effect of providing citrus pulp-integrated diet on fecal microbiota and serum and fecal metabolome shifts in crossbred pigs

The study aimed to assess the impact of dehydrated citrus pulp (DCP) on growth performance, fecal characteristics, fecal bacterial composition (based on 16S rRNA analysis), and fecal and serum metabolomic profiles in crossbred pigs. 80 finishing pigs Duroc × (Landrace × Large White) were fed either a control diet (C) or a diet with 240 g/kg DCP (T) for six weeks. Including DCP in diets tended to decrease feed intake, increased (p < 0.05) the concentrations of acetic and heptanoic acids and decreased (p < 0.05) fecal butyric and branched-chain fatty acid concentrations in feces. Animals fed DCP exhibited a lower abundance of the genera Clostridium and Romboutsia, while Lachnospira significantly increased. Orthogonal partial least squares discriminant analysis plotted a clear separation of fecal and serum metabolites between groups. The main discriminant fecal metabolites were associated with bacterial protein fermentation and were downregulated in T-fed pigs. In serum, DCP supplementation upregulated metabolites related to protein and fatty acids metabolism. In conclusion, the addition of DCP as an environmentally friendly source of nutrients in pig diets, resulted in modifications of fecal bacterial composition, fermentation patterns, and overall pig metabolism, suggesting improvements in protein metabolism and gut health.

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.

Diet-mediated gut microbial community modulation and signature metabolites as potential biomarkers for early diagnosis, prognosis, prevention and stage-specific treatment of colorectal cancer

BACKGROUND

Over the last decade, studies have shown an increased incidence of colorectal cancer (CRC), particularly early onset colorectal cancer (EOCRC). Researchers have demonstrated that dietary behavior, especially among young adults, influences alterations in the gut microbial community, leading to an increased accumulation of pathogenic gut microbiota and a decrease in beneficial ones. Unfortunately, CRC is likely to be diagnosed at a late stage, increasing CRC-related mortality. However, this alteration in the gut microbiota (gut dysbiosis) can be harnessed as a biomarker for non-invasive diagnosis, prognosis, prevention, and treatment of CRC in an effort to prevent late diagnosis and poor prognosis associated with CRC.

AIM OF REVIEW

This review discusses identification of potential biomarkers by targeting diet-mediated gut dysbiosis for the stage-specific diagnosis, prognosis, treatment, and prevention of CRC. Our findings provide a comprehensive insight into the potential of protumorigenic bacteria (e.g.pathogenic Escherichia coli,enterotoxigenic Bacteroides fragilis and Fusobacterium nucleatum) and their metabolites (e.g., colibactin and B. fragilis toxin) from gut dysbiosis as biomarkers for the diagnosis of CRC.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Collectively, a detailed understanding of the available data from current studies suggests that, further research on quantification of metabolites and stage-specific pathogenic microbial abundance is required for the diagnosis and treatment of CRC based on microbial dysbiosis. Specifically, future studies on faecal samples, from patient with CRC, should be conducted for F. nucleatum among different opportunistic bacteria, given its repeated occurrence in faecal samples and CRC biopsies in numerous studies. Finally, we discuss the potential of faecal microbial transplantation (FMT) as an intervention to restore damaged gut microbiota during CRC treatment and management.

Essential Amino Acid Metabolites as Chemical Mediators of Host-Microbe Interaction in the Gut

Amino acids are indispensable substrates for protein synthesis in all organisms and incorporated into diverse aspects of metabolic physiology and signaling. However, animals lack the ability to synthesize several of them and must acquire these essential amino acids from their diet or perhaps their associated microbial communities. The essential amino acids therefore occupy a unique position in the health of animals and their relationships with microbes. Here we review recent work connecting microbial production and metabolism of essential amino acids to host biology, and the reciprocal impacts of host metabolism of essential amino acids on their associated microbes. We focus on the roles of the branched-chain amino acids (valine, leucine, and isoleucine) and tryptophan on host-microbe communication in the intestine of humans and other vertebrates. We then conclude by highlighting research questions surrounding the less-understood aspects of microbial essential amino acid synthesis in animal hosts.