High-protein, reduced-carbohydrate weight-loss diets promote metabolite profiles likely to be detrimental to colonic health

Comparative genomic and metabolomic analysis reveals the potential of a newly isolated Enterococcus faecium B6 involved in lipogenic effects

Evidence has indicated that Enterococcus plays a vital role in non-alcoholic fatty liver disease (NAFLD) development. However, the microbial genetic basis and metabolic potential in the disease are yet unknown. We previously isolated a bacteria Enterococcus faecium B6 (E. faecium B6) from children with NAFLD for the first time. Here, we aim to systematically investigate the potential of strain B6 in lipogenic effects. The lipogenic effects of strain B6 were explored in vitro and in vivo. The genomic and functional characterizations were investigated by whole-genome sequencing and comparative genomic analysis. Moreover, the metabolite profiles were unraveled by an untargeted metabolomic analysis. We demonstrated that strain B6 could effectively induce lipogenic effects in the liver of mice. Strain B6 contained a circular chromosome and two circular plasmids and posed various functions. Compared to the other two probiotic strains of E. faecium, strain B6 exhibited unique functions in pathways of ABC transporters, phosphotransferase system, and amino sugar and nucleotide sugar metabolism. Moreover, strain B6 produced several metabolites, mainly enriched in the protein digestion and absorption pathway. The unique potential of strain B6 in lipogenic effects was probably associated with glycolysis, fatty acid synthesis, and glutamine and choline transport. This study pioneeringly revealed the metabolic characteristics and specific detrimental traits of strain B6. The findings provided new insights into the underlying mechanisms of E. faecium in lipogenic effects, and laid essential foundations for further understanding of E. faecium-related disease.

Understanding the microbiome as a mediator of bladder cancer progression and therapeutic response

Bladder cancer (BCa) remains a significant source of morbidity and mortality. BCa is one of the most expensive tumors to treat, in part because of a lack of nonsurgical options. The recent advent of immunotherapy, alone or in combination with other compounds, has improved therapeutic options. Resistance to immunotherapy remains common, and many patients do not have durable response. Recent advances indicate immunotherapy efficacy may be tied in part to the endogenous bacteria present in our body, more commonly referred to as the microbiome. Laboratory and clinical data now support the idea that a healthy microbiome is critical to effective response to immunotherapy. At the same time, pathogenic interactions between the microbiome and immune cells can also serve to drive formation of tumors, increasing the complexity of these interactions. Given the rising importance of immunotherapy in BCa, understanding how we might be able to alter the microbiome to improve therapeutic efficacy offers a novel route to improved patient care. The goal of this review is to examine our current understanding of microbial interactions with the immune system and cancer with an emphasis on BCa. We will further attempt to define both current gaps in knowledge and future directions that may yield beneficial results to the field.

Insights into the gut-kidney axis and implications for chronic kidney disease management in cats and dogs

Chronic kidney disease (CKD) in cats and dogs presents significant clinical challenges, with emerging research highlighting the pivotal role of the gut-kidney axis in its pathogenesis and management. Gut dysbiosis, characterized by alterations in the gut microbiome composition and function, contributes to microbial dysmetabolism of key nutrients causing uremic toxin accumulation and disruptions in amino acid, bile acid and fatty acid profiles. These disturbances in turn exacerbate renal dysfunction and systemic inflammation. Recent research in veterinary medicine, particularly in cats, supports the gut microbiome and microbial-derived metabolites as novel therapeutic targets. Potential therapeutic strategies targeting the gut microbiome and microbial dysmetabolism, including dietary management, probiotics, adsorbents, and addressing constipation, offer promising avenues for intervention to restore metabolic balance and preserve renal function. This review highlights the microbial influence on renal health and focuses on potential therapeutic strategies available to veterinarians to optimize the management of CKD in cats and dogs.

Impact of a Fruit-Vegetable Preparation Fortified with Potato Starch Resistant Dextrin on Selected Health Indicators in Overweight Children

Developing modified dietary fibers that maintain prebiotic benefits without significantly affecting meal taste is of high importance in the midst of the obesity pandemic. These benefits include regulating the composition of gut microbiota, increasing feelings of fullness, and improving human metabolic parameters. This study investigated the use of a resistant dextrin (RD) derived from potato starch, which possesses prebiotic properties, as a potential additive in vegetable-fruit preparations that aid weight loss and improve health markers in overweight children. HPLC was employed to examine metabolites like lactic acid, short-chain fatty acids (SCFAs; formic, acetic, propionic, butyric, and valeric acids), and branched-chain fatty acids (BCFAs; isobutyric and isovaleric acids). The activities of α-glucosidase, β-glucosidase, α-galactosidase, β-galactosidase, and β-glucuronidase enzymes in fecal samples were measured using spectrophotometric analysis at a wavelength of 400 nm. Incorporating the RD into vegetable-fruit preparations yielded favorable outcomes in terms of increased concentrations of the tested metabolites (SCFAs and BCFAs) and enhanced fecal enzyme activities after 6 months of consuming the preparations. Furthermore, these effects were found to last for an extended period of 3 months even after discontinuing the treatment. The study has shown that including RD into vegetable-fruit preparations enhances the metabolic parameters of obese and overweight children, hence providing a strong rationale for the widespread usage of these preparations in the industry.

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.

Maternal Body Mass Index Associates with Prenatal Characteristics and Fecal Microbial Communities

The maternal microbiome plays a vital role in shaping pregnancy outcomes, but there remains a substantial gap in understanding its precise relationships to maternal health, particularly in relation to potential effects of body mass index (BMI) on gut microbial diversity. The aim of this observational study was to assess maternal characteristics in association with pre-pregnancy BMI and to further assess microbial diversity in association with specific maternal characteristics. Eighty-four pregnant women were recruited during their third trimester of pregnancy from various prenatal clinics across the state of Michigan. The participants completed an enrollment questionnaire including self-reported pre-pregnancy BMI; stool samples were collected to assess the fecal microbial community composition. Pre-pregnancy obesity (BMI 30+) was associated (univariably) with antibiotic use before pregnancy, ever smoked, lower education level, and being unmarried. The gut microbiota alpha diversity was significantly different for pregnant women by pre-pregnancy BMI category (normal, overweight, obese). The beta diversity was unique for the gut microbiotas of pregnant women within each BMI category, by education level, and by marital status. Multivariable models revealed that pre-pregnancy BMI, maternal education, marital status, and maternal age were associated with the microbial diversity of the gut microbiota during pregnancy. These results give new insight into the relationship between a woman's microbiome during pregnancy and their prenatal health, along with an understanding of the relationships between socioeconomic factors and microbial diversity.

A mechanistic modelling approach of the host-microbiota interactions to investigate beneficial symbiotic resilience in the human gut

The health and well-being of a host are deeply influenced by the interactions with its gut microbiota. Contrasted environmental conditions, such as diseases or dietary habits, play a pivotal role in modulating these interactions, impacting microbiota composition and functionality. Such conditions can also lead to transitions from beneficial to detrimental symbiosis, viewed as alternative stable states of the host-microbiota dialogue. This article introduces a novel mathematical model exploring host-microbiota interactions, integrating dynamics of the colonic epithelial crypt, microbial metabolic functions, inflammation sensitivity and colon flows in a transverse section. The model considers metabolic shifts in epithelial cells based on butyrate and hydrogen sulfide concentrations, innate immune pattern recognition receptor activation, microbial oxygen tolerance and the impact of antimicrobial peptides on the microbiota. Using the model, we demonstrated that a high-protein, low-fibre diet exacerbates detrimental interactions and compromises beneficial symbiotic resilience, underscoring a destabilizing effect towards an unhealthy state. Moreover, the proposed model provides essential insights into oxygen levels, fibre and protein breakdown, and basic mechanisms of innate immunity in the colon and offers a crucial understanding of factors influencing the colon environment.

Prevotella enterotype associates with diets supporting acidic faecal pH and production of propionic acid by microbiota

Metabolism of dietary fibres by colon microbiota plays an important role for human health. Personal data from a nutrition study (57 subjects) were analysed to elucidate quantitative associations between the diet, faecal microbiome, organic acid concentrations and pH. Ratios of the predominant acids acetate, butyrate and propionate ranged from 1:0.67:0.27 to 1:0.17:0.36. Pectin-rich diets resulted in higher faecal acetate concentrations. Negative correlation between faecal pH and BSS was observed. Higher faecal pH and lower acid concentrations were related to the higher abundance of amino acid degrading Clostridium, Odoribacter and Eubacterium coprostanoligenes, which are weak carbohydrate fermenting taxa. Propionic acid correlated especially to high abundance of Prevotella and low abundance of proteobacteria. The acetate to propionate ratio of the Prevotella enterotype was about half of that of the Bacteroides enterotype. Based on the results we suggest the measurement of faecal pH and organic acid composition for research and diagnostic purposes.

The microbiota-gut-brain-immune interface in the pathogenesis of neuroinflammatory diseases: a narrative review of the emerging literature

Importance

Research is beginning to elucidate the sophisticated mechanisms underlying the microbiota-gut-brain-immune interface, moving from primarily animal models to human studies. Findings support the dynamic relationships between the gut microbiota as an ecosystem (microbiome) within an ecosystem (host) and its intersection with the host immune and nervous systems. Adding this to the effects on epigenetic regulation of gene expression further complicates and strengthens the response. At the heart is inflammation, which manifests in a variety of pathologies including neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and Multiple Sclerosis (MS).

Observations

Generally, the research to date is limited and has focused on bacteria, likely due to the simplicity and cost-effectiveness of 16s rRNA sequencing, despite its lower resolution and inability to determine functional ability/alterations. However, this omits all other microbiota including fungi, viruses, and phages, which are emerging as key members of the human microbiome. Much of the research has been done in pre-clinical models and/or in small human studies in more developed parts of the world. The relationships observed are promising but cannot be considered reliable or generalizable at this time. Specifically, causal relationships cannot be determined currently. More research has been done in Alzheimer's disease, followed by Parkinson's disease, and then little in MS. The data for MS is encouraging despite this.

Conclusions and relevance

While the research is still nascent, the microbiota-gut-brain-immune interface may be a missing link, which has hampered our progress on understanding, let alone preventing, managing, or putting into remission neurodegenerative diseases. Relationships must first be established in humans, as animal models have been shown to poorly translate to complex human physiology and environments, especially when investigating the human gut microbiome and its relationships where animal models are often overly simplistic. Only then can robust research be conducted in humans and using mechanistic model systems.

Effects of dietary fibre on metabolic health and obesity

Obesity and metabolic syndrome represent a growing epidemic worldwide. Body weight is regulated through complex interactions between hormonal, neural and metabolic pathways and is influenced by numerous environmental factors. Imbalances between energy intake and expenditure can occur due to several factors, including alterations in eating behaviours, abnormal satiation and satiety, and low energy expenditure. The gut microbiota profoundly affects all aspects of energy homeostasis through diverse mechanisms involving effects on mucosal and systemic immune, hormonal and neural systems. The benefits of dietary fibre on metabolism and obesity have been demonstrated through mechanistic studies and clinical trials, but many questions remain as to how different fibres are best utilized in managing obesity. In this Review, we discuss the physiochemical properties of different fibres, current findings on how fibre and the gut microbiota interact to regulate body weight homeostasis, and knowledge gaps related to using dietary fibres as a complementary strategy. Precision medicine approaches that utilize baseline microbiota and clinical characteristics to predict individual responses to fibre supplementation represent a new paradigm with great potential to enhance weight management efficacy, but many challenges remain before these approaches can be fully implemented.

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.

High-protein high-konjac glucomannan diets changed glucose and lipid metabolism by modulating colonic microflora and bile acid profiles in healthy mouse models

High protein and fiber diets are becoming increasingly popular for weight loss; however, the benefits or risks of high protein and fiber diets with a normal calorie level for healthy individuals still need to be elucidated. In this study, we explored the role and mechanisms of long-term high protein and/or konjac glucomannan diets on the metabolic health of healthy mouse models. We found that high konjac glucomannan contents improved the glucose tolerance of mice and both high protein and high konjac glucomannan contents improved the serum lipid profile but increased the TNF-α levels. In the liver, high dietary protein contents reduced the expression of the FASN gene related to fatty acid synthesis. Interactions of dietary protein and fiber were shown in the signaling pathways related to lipid and glucose metabolism of the liver and the inflammatory status of the colon, wherein the high protein and high konjac glucomannan diet downregulated the expression of the SREBF1 and FXR genes in the liver and downregulated the expression of TNF-α genes in the colon compared to the high protein diet. High konjac glucomannan contents reduced the colonic secondary bile acid levels including DCA and LCA; this was largely associated with the changed microbiota profile and also contributed to improved lipid and glucose homeostasis. In conclusion, high protein diets improved lipid homeostasis and were not a risk to metabolic health, while high fiber diets improved glucose and lipid homeostasis by modulating colonic microbiota and bile acid profiles, and a high protein diet supplemented with konjac glucomannan might improve hepatic lipid homeostasis and colonic inflammation in healthy mouse models through long-term intervention.

Systemic Effects of a Phage Cocktail on Healthy Weaned Piglets

Numerous studies have demonstrated that bacteriophages (phages) can effectively treat intestinal bacterial infections. However, research on the impact of phages on overall body health once they enter the intestine is limited. This study utilized weaned piglets as subjects to evaluate the systemic effects of an orally administered phage cocktail on their health. Twelve 21-day-old weaned piglets were divided into control (CON) and phage gavage (Phages) groups. The phage cocktail consisted of five lytic phages, targeting Salmonella enterica serovar Choleraesuis (S. choleraesuis), Enteropathogenic Escherichia coli (EPEC), and Shiga tox-in-producing Escherichia coli (STEC). The phages group received 10 mL of phage cocktail orally for 20 consecutive days. The results show that the phage gavage did not affect the piglets' growth performance, serum biochemical indices, or most organ indices, except for the pancreas. However, the impact on the intestine was complex. Firstly, although the pancreatic index decreased, it did not affect the secretion of digestive enzymes in the intestine. Secondly, phages increased the pH of jejunum chyme and relative weight of the ileum, and enhanced intestinal barrier function without affecting the morphology of the intestine. Thirdly, phages did not proliferate in the intestine, but altered the intestinal microbiota structure and increased concentrations of microbial metabolites isobutyric acid and isovaleric acid in the colonic chyme. In addition, phages impacted the immune status, significantly increasing serum IgA, IgG, and IgM, as well as serum and intestinal mucosal IFN-γ, IL-1β, IL-17, and TGF-β, and decreasing IL-4 and IL-10. They also activated toll-like receptors TLR-4 and TLR-9. Apart from an increase in basophil numbers, the counts of other immune cells in the blood did not change. This study indicates that the impact of phages on body health is complex, especially regarding immune status, warranting further attention. Short-term phage gavage did not have significant negative effects on health but could enhance intestinal barrier function.

Gut Bacteria Provide Genetic and Molecular Reporter Systems to Identify Specific Diseases

With genetic information gained from next-generation sequencing (NGS) and genome-wide association studies (GWAS), it is now possible to select for genes that encode reporter molecules that may be used to detect abnormalities such as alcohol-related liver disease (ARLD), cancer, cognitive impairment, multiple sclerosis (MS), diabesity, and ischemic stroke (IS). This, however, requires a thorough understanding of the gut-brain axis (GBA), the effect diets have on the selection of gut microbiota, conditions that influence the expression of microbial genes, and human physiology. Bacterial metabolites such as short-chain fatty acids (SCFAs) play a major role in gut homeostasis, maintain intestinal epithelial cells (IECs), and regulate the immune system, neurological, and endocrine functions. Changes in butyrate levels may serve as an early warning of colon cancer. Other cancer-reporting molecules are colibactin, a genotoxin produced by polyketide synthetase-positive Escherichia coli strains, and spermine oxidase (SMO). Increased butyrate levels are also associated with inflammation and impaired cognition. Dysbiosis may lead to increased production of oxidized low-density lipoproteins (OX-LDLs), known to restrict blood vessels and cause hypertension. Sudden changes in SCFA levels may also serve as a warning of IS. Early signs of ARLD may be detected by an increase in regenerating islet-derived 3 gamma (REG3G), which is associated with changes in the secretion of mucin-2 (Muc2). Pro-inflammatory molecules such as cytokines, interferons, and TNF may serve as early reporters of MS. Other examples of microbial enzymes and metabolites that may be used as reporters in the early detection of life-threatening diseases are reviewed.

Impact of dietary carbohydrate, fat or protein restriction on the human gut microbiome: a systematic review

Restriction of dietary carbohydrates, fat and/or protein is often used to reduce body weight and/or treat (metabolic) diseases. Since diet is a key modulator of the human gut microbiome, which plays an important role in health and disease, this review aims to provide an overview of current knowledge of the effects of macronutrient-restricted diets on gut microbial composition and metabolites. A structured search strategy was performed in several databases. After screening for inclusion and exclusion criteria, thirty-six articles could be included. Data are included in the results only when supported by at least three independent studies to enhance the reliability of our conclusions. Low-carbohydrate (<30 energy%) diets tended to induce a decrease in the relative abundance of several health-promoting bacteria, including Bifidobacterium, as well as a reduction in short-chain fatty acid (SCFA) levels in faeces. In contrast, low-fat diets (<30 energy%) increased alpha diversity, faecal SCFA levels and abundance of some beneficial bacteria, including Faecalibacterium prausnitzii. There were insufficient data to draw conclusions concerning the effects of low-protein (<10 energy%) diets on gut microbiota. Although the data of included studies unveil possible benefits of low-fat and potential drawbacks of low-carbohydrate diets for human gut microbiota, the diversity in study designs made it difficult to draw firm conclusions. Using a more uniform methodology in design, sample processing and sharing raw sequence data could foster our understanding of the effects of macronutrient restriction on gut microbiota composition and metabolic dynamics relevant to health. This systematic review was registered at https://www.crd.york.ac.uk/prospero as CRD42020156929.

The Development and Evaluation of a Literature-Based Dietary Index for Gut Microbiota

The aim of the study was to develop and evaluate a novel dietary index for gut microbiota (DI-GM) that captures dietary composition related to gut microbiota profiles. We conducted a literature review of longitudinal studies on the association of diet with gut microbiota in adult populations and extracted those dietary components with evidence of beneficial or unfavorable effects. Dietary recall data from the National Health and Nutrition Examination Survey (NHANES, 2005-2010, n = 3812) were used to compute the DI-GM, and associations with biomarkers of gut microbiota diversity (urinary enterodiol and enterolactone) were examined using linear regression. From a review of 106 articles, 14 foods or nutrients were identified as components of the DI-GM, including fermented dairy, chickpeas, soybean, whole grains, fiber, cranberries, avocados, broccoli, coffee, and green tea as beneficial components, and red meat, processed meat, refined grains, and high-fat diet (≥40% of energy from fat) as unfavorable components. Each component was scored 0 or 1 based on sex-specific median intakes, and scores were summed to develop the overall DI-GM score. In the NHANES, DI-GM scores ranged from 0-13 with a mean of 4.8 (SE = 0.04). Positive associations between DI-GM and urinary enterodiol and enterolactone were observed. The association of the novel DI-GM with markers of gut microbiota diversity demonstrates the potential utility of this index for gut health-related studies.

Different Levels of Therapeutic Strategies to Recover the Microbiome to Prevent/Delay Acute Lymphoblastic Leukemia (ALL) or Arrest Its Progression in Children

Changes in the components, variety, metabolism, and products of microbiomes, particularly of the gut microbiome (GM), have been revealed to be closely associated with the onset and progression of numerous human illnesses, including hematological neoplasms. Among the latter pathologies, there is acute lymphoblastic leukemia (ALL), the most widespread malignant neoplasm in pediatric subjects. Accordingly, ALL cases present a typical dysfunctional GM during all its clinical stages and resulting inflammation, which contributes to its progression, altered response to therapy, and possible relapses. Children with ALL have GM with characteristic variations in composition, variety, and functions, and such alterations may influence and predict the complications and prognosis of ALL after chemotherapy treatment or stem cell hematopoietic transplants. In addition, growing evidence also reports the ability of GM to influence the formation, growth, and roles of the newborn's hematopoietic system through the process of developmental programming during fetal life as well as its susceptibility to the onset of onco-hematological pathologies, namely ALL. Here, we suggest some therapeutic strategies that can be applied at two levels of intervention to recover the microbiome and consequently prevent/delay ALL or arrest its progression.

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.

The role of microbial metabolites in endocrine tumorigenesis: From the mechanistic insights to potential therapeutic biomarkers

Microbial metabolites have been indicated to communicate with the host's endocrine system, regulating hormone production, immune-endocrine communications, and interactions along the gut-brain axis, eventually affecting the occurrence of endocrine cancer. Furthermore, microbiota metabolites such as short-chain fatty acids (SCFAs) have been found to affect the tumor microenvironment and boost immunity against tumors. SCFAs, including butyrate and acetate, have been demonstrated to exert anti-proliferative and anti-protective activity on pancreatic cancer cells. The employing of microbial metabolic products in conjunction with radiation and chemotherapy has shown promising outcomes in terms of reducing treatment side effects and boosting effectiveness. Certain metabolites, such as valerate and butyrate, have been made known to improve the efficiency of CAR T-cell treatment, whilst others, such as indole-derived tryptophan metabolites, have been shown to inhibit tumor immunity. This review explores the intricate interplay between microbial metabolites and endocrine tumorigenesis, spanning mechanistic insights to the discovery of potential therapeutic biomarkers.

Nutrition at the Intersection between Gut Microbiota Eubiosis and Effective Management of Type 2 Diabetes

Nutrition is one of the most influential environmental factors in both taxonomical shifts in gut microbiota as well as in the development of type 2 diabetes mellitus (T2DM). Emerging evidence has shown that the effects of nutrition on both these parameters is not mutually exclusive and that changes in gut microbiota and related metabolites such as short-chain fatty acids (SCFAs) and branched-chain amino acids (BCAAs) may influence systemic inflammation and signaling pathways that contribute to pathophysiological processes associated with T2DM. With this background, our review highlights the effects of macronutrients, carbohydrates, proteins, and lipids, as well as micronutrients, vitamins, and minerals, on T2DM, specifically through their alterations in gut microbiota and the metabolites they produce. Additionally, we describe the influences of common food groups, which incorporate varying combinations of these macronutrients and micronutrients, on both microbiota and metabolic parameters in the context of diabetes mellitus. Overall, nutrition is one of the first line modifiable therapies in the management of T2DM and a better understanding of the mechanisms by which gut microbiota influence its pathophysiology provides opportunities for optimizing dietary interventions.

Faecal microbiota and fatty acids in feline chronic enteropathy

BACKGROUND

Feline chronic enteropathy is a set of disorders defined as the presence of clinical signs of gastrointestinal disease for at least three weeks. The most common final diagnoses are inflammatory bowel disease and alimentary small cell lymphoma. The etiopathogenesis of these diseases is incompletely understood; however, it is hypothesised that they involve a combination of factors, including altered composition and/or functionality of the intestinal microbiome. An important factor in the interplay of the microbiome and host is the production of short- and branched-chain fatty acids.  The aim of this study was to evaluate the possible differences in faecal microbiota diversity, composition and fatty acid production between cats suffering from chronic enteropathy and healthy cats. Sixteen cats suffering from chronic enteropathy and fourteen healthy control cats were enrolled in the study. The microbiota compositions of faecal samples were analysed by using next-generation amplicon sequencing of the V3V4 fragment of the 16S rRNA gene. Fatty acids were evaluated by high-performance liquid chromatography.

RESULTS

Both the alpha and beta diversities were significantly lower in samples obtained from cats with chronic enteropathy. The relative abundance of the phylum Proteobacteria, orders Lactobacillales and Enterobacterales, family Enteriobacteriaceae and genus Escherichia Shigella were higher in diseased cats, whereas the abundance of the phylum Bacteroidota and order Peptococcales were higher in control cats. The faecal concentrations of short-chain fatty acids were higher in cats with chronic enteropathy, with lower propionate proportions and higher butyrate proportions.

CONCLUSION

The study revealed alterations in microbiota compositions and short-chain fatty acid concentration in cats suffering from chronic enteropathy, which is an important finding both for research on the pathogenesis of the disease and for potential therapeutic interventions in the form of faecal microbiota transplantation and/or probiotic supplementation.

The potential role of early life feeding patterns in shaping the infant fecal metabolome: implications for neurodevelopmental outcomes

Infant fecal metabolomics can provide valuable insights into the associations of nutrition, dietary patterns, and health outcomes in early life. Breastmilk is typically classified as the best source of nutrition for nearly all infants. However, exclusive breastfeeding may not always be possible for all infants. This study aimed to characterize associations between levels of mixed breastfeeding and formula feeding, along with solid food consumption and the infant fecal metabolome at 1- and 6-months of age. As a secondary aim, we examined how feeding-associated metabolites may be associated with early life neurodevelopmental outcomes. Fecal samples were collected at 1- and 6-months, and metabolic features were assessed via untargeted liquid chromatography/high-resolution mass spectrometry. Feeding groups were defined at 1-month as 1) exclusively breastfed, 2) breastfed >50% of feedings, or 3) formula fed ≥50% of feedings. Six-month groups were defined as majority breastmilk (>50%) or majority formula fed (≥50%) complemented by solid foods. Neurodevelopmental outcomes were assessed using the Bayley Scales of Infant Development at 2 years. Changes in the infant fecal metabolome were associated with feeding patterns at 1- and 6-months. Feeding patterns were associated with the intensities of a total of 57 fecal metabolites at 1-month and 25 metabolites at 6-months, which were either associated with increased breastmilk or increased formula feeding. Most breastmilk-associated metabolites, which are involved in lipid metabolism and cellular processes like cell signaling, were associated with higher neurodevelopmental scores, while formula-associated metabolites were associated with lower neurodevelopmental scores. These findings offer preliminary evidence that feeding patterns are associated with altered infant fecal metabolomes, which may be associated with cognitive development later in life.

Dietary Inflammatory Potential in Pediatric Diseases: A Narrative Review

Inflammatory status is one of the main drivers in the development of non-communicable diseases (NCDs). Specific unhealthy dietary patterns and the growing consumption of ultra-processed foods (UPFs) may influence the inflammation process, which negatively modulates the gut microbiota and increases the risk of NCDs. Moreover, several chronic health conditions require special long-term dietary treatment, characterized by altered ratios of the intake of nutrients or by the consumption of disease-specific foods. In this narrative review, we aimed to collect the latest evidence on the pro-inflammatory potential of dietary patterns, foods, and nutrients in children affected by multifactorial diseases but also on the dietetic approaches used as treatment for specific diseases. Considering multifactorial diet-related diseases, the triggering effect of pro-inflammatory diets has been addressed for metabolic syndrome and inflammatory bowel diseases, and the latter for adults only. Future research is required on multiple sclerosis, type 1 diabetes, and pediatric cancer, in which the role of inflammation is emerging. For diseases requiring special diets, the role of single or multiple foods, possibly associated with inflammation, was assessed, but more studies are needed. The evidence collected highlighted the need for health professionals to consider the entire dietary pattern, providing balanced and healthy diets not only to permit the metabolic control of the disease itself, but also to prevent the development of NCDs in adolescence and adulthood. Personalized nutritional approaches, in close collaboration between the hospital, country, and families, must always be promoted together with the development of new methods for the assessment of pro-inflammatory dietary habits in pediatric age and the implementation of telemedicine.

Long-Term Dietary Effects on Human Gut Microbiota Composition Employing Shotgun Metagenomics Data Analysis

SCOPE

The gut microbiome regulates various metabolic pathways in the host and its dysbiosis is involved in the pathogenesis of diverse diseases. One of the major factors triggering gut microbiome establishment is diet. This study aims to unravel interactions and changes between diet and gut microbiome over a period of 3 years.

METHODS AND RESULTS

This study investigates the relation between diet and the microbiome of 75 individuals over a 3-year time period. Shotgun metagenomic sequencing is performed to profile gut microbial composition and function. This study shows that there are significant changes in gut microbiome taxonomy and functional composition between two time points. Whereas microbial taxonomy is found to be highly individualized, overall microbial functions stay relatively stable. Moreover, in silico metabolic modeling of microbial communities indicates that changes in dietary intake of medium-chain saturated fatty acids is accompanied by an altered utilization of amino acids by the gut microbiome.

CONCLUSION

The study design allows us to validate functional stability within the gut microbiome of healthy subjects over a 3-year period. However, enduring changes in nutrition such as increased alcohol consumption or decreased intake of vegetables come along with enhanced microbial functions that are associated with disease etiology.

Microbiota regulation by different Akebia trifoliata fruit juices upon human fecal fermentation in vitro

Three different Akebia trifoliata fruit juices were prepared, and their effects on modulation of human fecal microbiota were elucidated through an anaerobic fermentation in vitro. Results indicated that the introduction of inoculatedly-fermented Akebia trifoliata fruit juice promoted short-chain fatty acids productivity. Fecal microbiota analysis demonstrated up-regulations for abundances of Limosilactobacillus, Megamonas, Bifidobacterium, and Escherichia_Shigella, and down-regulations for numbers of Bacteroides, Prevotella_9, Parasutterella, and Sutterella. Correlation analysis confirmed relationships among sample components, short-chain fatty acids productivity, and microbial abundances, suggesting that sugars and organic acids stimulated growth of Actinobacteriota and suppressed proliferation of Proteobacteria, thus uncovering the underlying mechanism for the better ability of inoculatedly-fermented Akebia trifoliata fruit juice to regulate microbiota structure. Besides, clusters of orthologous groups of proteins analysis indicated that metabolite biosynthesis, energy metabolism, homeostasis maintenance and other physiological functions were ameliorated.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01308-y.

Programming of metabolic and autoimmune diseases in canine and feline: linkage to the gut microbiome

Metabolic and autoimmune disorders have long represented challenging health problems because of their growing prevalence in companion animals. The gut microbiome, made up of trillions of microorganisms, is implicated in multiple physiological and pathological processes. Similar to human beings, the complicated microbiome harbored in the gut of canines and felines emerges as a key factor determining a wide range of normal and disease conditions. Evidence accumulated from recent findings on canine and feline research uncovered that the gut microbiome is actively involved in host metabolism and immunity. Notably, the composition, abundance, activity, and metabolites of the gut microbiome are all elements that shape clinical outcomes concerning metabolism and immune function. This review highlights the implications of the gut microbiome for metabolic disorders (obesity, diabetes, and hepatic lipidosis) and autoimmune diseases (inflammatory bowel disease, osteoarthritis, asthma, and myasthenia gravis) in canine and feline animals, providing novel strategies and therapeutic targets for the prevention and treatment of pet diseases.

Gut Microbiome-Generated Phenylacetylglutamine from Dietary Protein is Associated with Crohn's Disease and Exacerbates Colitis in Mouse Model Possibly via Platelet Activation

OBJECTIVES

Our aims were to better understand the interplay of diet and gut microbiota in Crohn's disease [CD], taking advantage of a new-onset treatment-naïve CD cohort. We focus on phenylacetylglutamine [PAGln], a diet-derived meta-organismal prothrombotic metabolite.

DESIGN

We collected faecal and serum samples from a CD cohort [n = 136] and healthy controls [n = 126] prior to treatment, and quantified serum PAGln using LC-MS/MS. Diet was assessed using food-frequency questionnaires. Mice [C57BL/6] were fed high/low-protein diets and administered dextran sodium sulphate [DSS] to examine plasma PAGly, thrombosis potential, and colitis severity. PAGly or saline was administered to DSS-induced colitis mice, and colitis severity and colonic tissue gene expression were examined. P-selectin and CD40L expression were determined in human platelet-rich plasma [n = 5-6] after exposure to platelet agonists following PAGln priming. Bioinformatic analysis and bacterial culturing identified the main contributor of PAGln in CD.

RESULTS

PAGln, a meta-organismal prothrombotic metabolite, is associated with CD. Administration of PAGly exacerbated colitis in a mouse model and upregulated coagulation-related biological processes. Antiplatelet medicine, dipyridamole, attenuated PAGly-enhanced colitis susceptibility. PAGln enhanced platelet activation and CD40L expression in platelet-rich plasma ex vivo. Further study revealed that high dietary protein intake and increased abundance of phenylacetic acid [PAA]-producing Proteobacteria mediated by phenylpyruvate decarboxylase act in concert to cause the elevated PAGln levels in CD patients.

CONCLUSION

Taken together, ppdc-carrying Proteobacteria-generated PAGln from dietary protein is associated with CD and exacerbates colitis possibly via platelet-induced coagulation and inflammation These results suggest that PAGln is a potential early diagnostic marker and therapeutic target of CD.

Targeting microbiota in dietary obesity management: a systematic review on randomized control trials in adults

Obesity is an alarming public health problem. Tailored nutritional therapy is advisable since emerging evidence on complex cross-talks among multifactorial agents. In this picture, the gut microbiota is highly individualized and intricately dependent on dietary patterns, with implications for obesity management. Most of the papers on the topic are observational and often conflicting. This review aimed to systematically organize the body of evidence on microbiota deriving from dietary trials in adult obesity giving the most certain phylogenetic, and metabolomic signatures in relation to both the host metabolism and phenotype changes published until now. We retrieved 18 randomized control trials on 1385 subjects with obesity who underwent several dietary interventions, including standard diet and healthy dietary regimens. Some phyla and species were more related to diets rich in fibers and others to healthy diets. Weight loss, metabolism improvements, inflammatory markers decrease were specifically related to different microorganisms or functions. The Prevotella/Bacteroides ratio was one of the most reported predictors. People with the burden of obesity comorbidities had the most significant taxonomic changes in parallel with a general improvement. These data emphasize the possibility of using symbiotic approaches involving tailored diets, microbiota characteristics, and maybe drugs to treat obesity and metabolic disorders. We encourage Authors to search for specific phylogenetic associations beyond a too generally reported Firmicutes/Bacteroides ratio.

Interaction between high-intensity interval training and high-protein diet on gut microbiota composition and body weight in obese male rats

Diet and exercise are two critical factors that regulate gut microbiota, affecting weight management. The present study investigated the effect of 10 weeks of high-intensity interval training (HIIT) and a high-protein diet (HPD) on gut microbiota composition and body weight changes in obese male Wistar rats. Forty obese rats were randomly divided into five groups, including HPD, HIIT + HPD, HIIT + high-fat diet (HFD) (continuing HFD during intervention), obese control 1 (continuing HFD during intervention), obese control 2 (cutting off HFD at the beginning of the intervention and continuing standard diet), and eight non-obese Wistar rats as a non-obese control (NOC) group (standard diet). Microbial community composition and diversity analysis by sequencing 16S rRNA genes derived from the fecal samples, body weight, and Lee index were assessed. The body weight and Lee index in the NOC, HIIT + HFD, HPD, and HIIT + HPD groups were significantly lower than that in the OC1 and OC2 groups along with the lower body weight and Lee index in the HPD and HIIT + HPD groups compared with the HIIT + HFD group. Also, HFD consumption and switching from HFD to a standard diet or HPD increased gut microbiota dysbiosis. Furthermore, HIIT along with HFD increased the adverse effects of HFD on gut microbiota, while the HIIT + HPD increased microbial richness, improved gut microbiota dysbiosis, and changed rats' phenotype to lean. It appears that HFD discontinuation without doing HIIT does not improve gut microbiota dysbiosis. Also, the HIIT + HFD, HPD, and HIIT + HPD slow down HFD-induced weight gain, but HIIT + HPD is a more reliable strategy for weight management due to its beneficial effects on gut microbiota composition.

Exploring high-protein diets in the context of cardiac rehabilitation

The review aims to explore the potential benefit and risk of high-protein diets (HPD) regarding the comorbidity of sarcopoenia and CVD in the setting of cardiac rehabilitation (CR). CR is standard care for individuals who have experienced a cardiac event, but the current practice of predominantly aerobic exercise, a lower-fat diet and weight loss poorly addresses the issue of sarcopoenia. HPD, especially when combined with resistance exercise (RE), may be valuable adjuncts to current CR practice and benefit both muscle and cardiovascular health. Meta-analyses and randomised controlled trials of HPD and CVD risk show beneficial but variable effects regarding weight loss, the lipid profile, insulin resistance and lean body mass in those living with or high risk of CVD. Meta-analyses of prospective cohort studies on hard CVD endpoints favour lower- and plant-protein diets over higher animal protein, but the evidence is inconsistent. HPD augment the strength and muscle gaining benefits of RE in older populations, but there are no published data in those living with CVD providing promising opportunities for CR research. HPD raise concern regarding renal and bone health, the microbiome, branched chain amino acids and environmental sustainability and findings suggest that plant-based HPD may confer ecological and overall health advantages compared to animal-based HPD. However, incorporating RE with HPD might alleviate certain health risks. In conclusion, a largely plant-based HPD is deemed favourable for CR when combined with RE, but further research regarding efficacy and safety in CR populations is needed.

The Low-FODMAP Diet, IBS, and BCFAs: Exploring the Positive, Negative, and Less Desirable Aspects-A Literature Review

The literature about the association of branched short-chain fatty acids (BCFAs) and irritable bowel syndrome (IBS) is limited. BCFAs, the bacterial products of the catabolism of branched-chain amino acids, are proposed as markers for colonic protein fermentation. IBS is a gastrointestinal disorder characterized by low-grade inflammation and intestinal dysbiosis. The low-FODMAP diet (LFD) has increasingly been applied as first-line therapy for managing IBS symptoms, although it decreases the production of short-chain fatty acids (SCFA), well known for their anti-inflammatory action. In parallel, high protein consumption increases BCFAs. Protein fermentation alters the colonic microbiome through nitrogenous metabolites production, known for their detrimental effects on the intestinal barrier promoting inflammation. Purpose: This review aims to explore the role of BCFAs on gut inflammation in patients with IBS and the impact of LFD in BCFAs production. Methods: A literature search was carried out using a combination of terms in scientific databases. Results: The included studies have contradictory findings about how BCFAs affect the intestinal health of IBS patients. Conclusions: Although evidence suggests that BCFAs may play a protective role in gut inflammation, other metabolites of protein fermentation are associated with gut inflammation. Further research is needed in order to clarify how diet protein composition and, consequently, the BCFAs are implicated in IBS pathogenesis or in symptoms management with LFD+.

The First 1000 Days of Life: How Changes in the Microbiota Can Influence Food Allergy Onset in Children

BACKGROUND

Allergic disease, including food allergies (FA)s, has been identified as a major global disease. The first 1000 days of life can be a "window of opportunity" or a "window of susceptibility", during which several factors can predispose children to FA development. Changes in the composition of the gut microbiota from pregnancy to infancy may play a pivotal role in this regard: some bacterial genera, such as Lactobacillus and Bifidobacterium, seem to be protective against FA development. On the contrary, Clostridium and Staphylococcus appear to be unprotective.

METHODS

We conducted research on the most recent literature (2013-2023) using the PubMed and Scopus databases. We included original papers, clinical trials, meta-analyses, and reviews in English. Case reports, series, and letters were excluded.

RESULTS

During pregnancy, the maternal diet can play a fundamental role in influencing the gut microbiota composition of newborns. After birth, human milk can promote the development of protective microbial species via human milk oligosaccharides (HMOs), which play a prebiotic role. Moreover, complementary feeding can modify the gut microbiota's composition.

CONCLUSIONS

The first two years of life are a critical period, during which several factors can increase the risk of FA development in genetically predisposed children.

Effect of Consumption of Animal Products on the Gut Microbiome Composition and Gut Health

The gut microbiome is critical in human health, and various dietary factors influence its composition and function. Among these factors, animal products, such as meat, dairy, and eggs, represent crucial sources of essential nutrients for the gut microbiome. However, the correlation and characteristics of livestock consumption with the gut microbiome remain poorly understood. This review aimed to delineate the distinct effects of meat, dairy, and egg products on gut microbiome composition and function. Based on the previous reports, the impact of red meat, white meat, and processed meat consumption on the gut microbiome differs from that of milk, yogurt, cheese, or egg products. In particular, we have focused on animal-originated proteins, a significant nutrient in each livestock product, and revealed that the major proteins in each food elicit diverse effects on the gut microbiome. Collectively, this review highlights the need for further insights into the interactions and mechanisms underlying the impact of animal products on the gut microbiome. A deeper understanding of these interactions would be beneficial in elucidating the development of dietary interventions to prevent and treat diseases linked to the gut microbiome.

Undaria pinnatifida fucoidan ameliorates dietary fiber deficiency-induced inflammation and lipid abnormality by modulating mucosal microbiota and protecting intestinal barrier integrity

Dietary fiber deficiency (FD) is a new public health concern, with limited understanding of its impact on host energy requirements and health. In this study, the effect of fucoidan from Undaria pinnatifida (UPF) on FD-induced alterations of host physiological status was analyzed in mice. UPF increased colon length and cecum weight, reduced liver index, and modulated serum lipid metabolism primarily involving glycerophospholipid and linoleic acid metabolism in FD-treated mice. UPF protected against FD-induced destruction of intestinal barrier integrity by upregulating the expression levels of tight junction proteins and mucin-related genes. UPF alleviated FD-induced intestinal inflammation by reducing the levels of inflammation-related factors, such as interleukin-1β, tumor necrosis factor-α, and lipopolysaccharides, and relieving oxidative stress. The underlying mechanism can be closely associated with modulation of gut microbiota and metabolites, such as a reduction of Proteobacteria and an increase in short chain fatty acids. The in vitro model showed that UPF mitigated H2O2-induced oxidative stress and apoptosis in IEC-6 cells, indicating its potential as a therapeutic agent for inflammatory bowel disorders. This study suggests that UPF can be developed as a fiber supplement to benefit host health by modulating gut microbiota and metabolites and protecting intestinal barrier functions.

Immunomodulatory effects of inulin and its intestinal metabolites

"Dietary fiber" (DF) refers to a type of carbohydrate that cannot be digested fully. DF is not an essential nutrient, but it plays an important part in enhancing digestive capacity and maintaining intestinal health. Therefore, DF supplementation in the daily diet is highly recommended. Inulin is a soluble DF, and commonly added to foods. Recently, several studies have found that dietary supplementation of inulin can improve metabolic function and regulate intestinal immunity. Inulin is fermented in the colon by the gut microbiota and a series of metabolites is generated. Among these metabolites, short-chain fatty acids provide energy to intestinal epithelial cells and participate in regulating the differentiation of immune cells. Inulin and its intestinal metabolites contribute to host immunity. This review summarizes the effect of inulin and its metabolites on intestinal immunity, and the underlying mechanisms of inulin in preventing diseases such as type 2 diabetes mellitus, inflammatory bowel disease, chronic kidney disease, and certain cancer types.

In vitro fermentation properties of magnesium hydride and related modulation effects on broiler cecal microbiome and metabolome

Magnesium hydride (MGH), a highly promising hydrogen-producing substance/additive for hydrogen production through its hydrolysis reaction, has the potential to enhance broiler production. However, before incorporating MGH as a hydrogen-producing additive in broiler feed, it is crucial to fully understand its impact on microbiota and metabolites. In vitro fermentation models provide a fast, reproducible, and direct assessment tool for microbiota metabolism and composition. This study aims to investigate the effects of MGH and coated-magnesium hydride (CMG) on fermentation characteristics, as well as the microbiota and metabolome in the culture of in vitro fermentation using cecal inocula from broilers. After 48 h of incubation, it was observed that the presence of MGH had a significant impact on various factors. Specifically, the content of N-NH3 decreased, while the total hydrogen gas and total SCFAs increased. Furthermore, the presence of MGH promoted the abundance of SCFA-producing bacteria such as Ruminococcus, Blautia, Coprobacillus, and Dysgonomonas. On the other hand, the presence of CMG led to an increase in the concentration of lactic acid, acetic acid, and valeric acid. Additionally, CMG affected the diversity of microbiota in the culture, resulting in an enrichment of the relative abundance of Firmicutes, as well as genera of Lactobacillus, Coprococcus, and Eubacterium. Conversely, the relative abundance of the phylum Proteobacteria and pathogenic bacteria Shigella decreased. Metabolome analysis revealed that MGH and CMG treatment caused significant changes in 21 co-regulated metabolites, primarily associated with lipid, amino acid, benzenoids, and organooxygen compounds. Importantly, joint correlation analysis revealed that MGH or CMG treatments had a direct impact on the microbiota, which in turn indirectly influenced metabolites in the culture. In summary, the results of this study suggested that both MGH and coated-MGH have similar yet distinct positive effects on the microbiota and metabolites of the broiler cecal in an in vitro fermentation model.

Increasing Dietary Nutrient Levels Modulates Colon Immune Adaptation and Alleviates Inflammation in the Epithelial Heterogeneous Nuclear Ribonucleoprotein I (Hnrnp I) Knockout Mice

SCOPE

Heterogeneous nuclear ribonucleoprotein I (HNRNP I) is an RNA-binding protein essential for neonatal immune adaptation by downregulating interleukin-1 receptor-associated kinase (IRAK1) in toll-like receptor (TLR)-mediated NF-κB signaling pathways. TLR-mediated NF-κB is associated with chronic inflammation, including the development of inflammatory bowel diseases. Therefore, dietary protein intake is one of the major concerns for individuals with inflammatory bowel diseases. The present study aims to investigate the effects of a protein-enriched diet on intestinal inflammation and immune responses in a mouse model with aberrant NF-κB signaling in the colon.

METHODS AND RESULTS

A transgenic mouse model with intestinal-epithelial-cell (IEC) specific Hnrnp I knocked out was used to investigate the effects of protein intake on the immune system in the colon. A control diet (CON) and a nutrient-dense modified diet (MOD) were fed to both the wild-type (WT) and the knockout (KO) male mice for 14 weeks. Inflammatory markers and colonic immune responses were examined, with gene expression and protein expression levels analyzed. IEC-specific Hnrnp I knocked out mice had significantly increased expression of the active NF-κB subunit, P65, in their colons. There was a concomitant induction of mRNA expression of Il1β, Il6, Cxcl1, and Ccl2. The number of CD4⁺ T cells in the distal colon was also increased in the KO mice. The results confirmed that KO mice had pro-inflammatory responses with aberrant NF-κB signaling in the colon. Importantly, increased nutrient density in their diets attenuated colon inflammation by decreasing the expression of pro-inflammatory cytokines, reducing P65 translocation, downregulating IRAK1, and limiting the number of CD4⁺ T cells recruited in Hnrnp I KO mice colon.

CONCLUSION

A diet with increased nutrient density relieved the inflammation induced by knockout of Hnrnp I, attributable partially to the reduced expression of inflammatory and immune-modulating cytokines in the mouse distal colon.

A systematic review on the impact of gastrointestinal microbiota composition and function on cognition in healthy infants and children

Evidence from animal models or children with neurodevelopmental disorders has implicated the gut microbiome (GM) in neurocognitive development. However, even subclinical impairement of cognition can have negative consequences, as cognition serves as the foundation for skills necessary to succeed in school, vocation and socially. The present study aims to identify gut microbiome characteristics or changes in gut microbiome characteristics that consistently associate with cognitive outcomes in healthy, neurotypical infants and children. Of the 1,520 articles identified in the search, 23 were included in qualitative synthesis after applying exclusion criteria. Most studies were cross-sectional and focused on behavior or motor and language skills. Bifidobacterium, Bacteroides, Clostridia, Prevotella, and Roseburia were related to these aspects of cognition across several studies. While these results support the role of GM in cognitive development, higher quality studies focused on more complex cognition are needed to understand the extent to which the GM contributes to cognitive development.

Effects of Animal and Vegetable Proteins on Gut Microbiota in Subjects with Overweight or Obesity

The gut microbiota plays a pivotal role in the balance between host health and obesity. The composition of the gut microbiota can be influenced by external factors, among which diet plays a key role. As the source of dietary protein is important to achieve weight loss and gut microbiota modulation, in the literature there is increasing evidence to suggest consuming more plant proteins than animal proteins. In this review, a literature search of clinical trials published until February 2023 was conducted to examine the effect of different macronutrients and dietary patterns on the gut microbiota in subjects with overweight and obesity. Several studies have shown that a higher intake of animal protein, as well as the Western diet, can lead to a decrease in beneficial gut bacteria and an increase in harmful ones typical of obesity. On the other hand, diets rich in plant proteins, such as the Mediterranean diet, lead to a significant increase in anti-inflammatory butyrate-producing bacteria, bacterial diversity and a reduction in pro-inflammatory bacteria. Therefore, since diets rich in fiber, plant protein, and an adequate amount of unsaturated fat may help to beneficially modulate the gut microbiota involved in weight loss, further studies are needed.

A grape seed and bilberry extract reduces blood pressure in individuals at risk of developing type 2 diabetes: the PRECISE study, a double-blind placebo-controlled cross-over intervention study

Background

Type 2 Diabetes Mellitus (T2DM) is a major risk factor for the development of cardiometabolic diseases. T2DM prevention is largely based on weight-loss and whole diet changes, but intervention with dietary plant bioactives may also improve metabolic health.

Objective

To assess whether supplementation with bilberry and grape seed extract for 12 weeks improves cardiometabolic outcomes in individuals at risk of developing T2DM, and to determine whether individual treatment response is associated with differences in gut microbiota composition and levels of phenolic metabolites in blood and feces.

Methods

In the randomized, double-blind, placebo-controlled, cross-over PRECISE intervention study, 14 participants, aged ≥45 years, with a BMI >28 kg/m², and having an increased risk of T2DM, received a supplement containing 250 mg of bilberry plus 300 mg of grape seed extract, or 550 mg of a control extract, per day, for 12 weeks each. Blood samples were obtained for the assessment of HbA1c, fasting glucose, oral glucose tolerance tests, insulin, glucagon levels, total, LDL and HDL cholesterol, and phenolic acids. We also assessed advanced glycation end products in the skin, ambulatory 24 hours blood pressure, 7-day dietary intake by weighed food diaries, fecal levels of phenolic metabolites using LC-MS/MS and gut microbiota composition using 16S rRNA gene sequencing analysis.

Results

The combined bilberry and grape seed extract did not affect glucose and cholesterol outcomes, but it decreased systolic and diastolic ambulatory blood pressure by 4.7 (p < 0.001) and 2.3 (p = 0.0009) mmHg, respectively. Eight out of fourteen participants were identified as blood pressure 'responders'. These responders had higher levels of phenylpropionic and phenyllactic acids in their fecal samples, and a higher proportional abundance of Fusicatenibacter-related bacteria (p < 0.01) in their baseline stool samples.

Conclusion

Long-term supplementation with bilberry and grape seed extract can improve systolic and diastolic blood pressure in individuals at risk of T2DM. Individual responsiveness was correlated with the presence of certain fecal bacterial strains, and an ability to metabolize (epi)catechin into smaller phenolic metabolites.Clinical trial registry number: Research Registry (number 4084).

Food System Transformation and Gut Microbiota Transition: Evidence on Advancing Obesity, Cardiovascular Diseases, and Cancers-A Narrative Review

Food, a vital component of our daily life, is fundamental to our health and well-being, and the knowledge and practices relating to food have been passed down from countless generations of ancestors. Systems may be used to describe this extremely extensive and varied body of agricultural and gastronomic knowledge that has been gathered via evolutionary processes. The gut microbiota also underwent changes as the food system did, and these alterations had a variety of effects on human health. In recent decades, the gut microbiome has gained attention due to its health benefits as well as its pathological effects on human health. Many studies have shown that a person's gut microbiota partially determines the nutritional value of food and that diet, in turn, shapes both the microbiota and the microbiome. The current narrative review aims to explain how changes in the food system over time affect the makeup and evolution of the gut microbiota, advancing obesity, cardiovascular disease (CVD), and cancer. After a brief discussion of the food system's variety and the gut microbiota's functions, we concentrate on the relationship between the evolution of food system transformation and gut microbiota system transition linked to the increase of non-communicable diseases (NCDs). Finally, we also describe sustainable food system transformation strategies to ensure healthy microbiota composition recovery and maintain the host gut barrier and immune functions to reverse advancing NCDs.

Specific host metabolite and gut microbiome alterations are associated with bone loss during spaceflight

Understanding the axis of the human microbiome and physiological homeostasis is an essential task in managing deep-space-travel-associated health risks. The NASA-led Rodent Research 5 mission enabled an ancillary investigation of the gut microbiome, varying exposure to microgravity (flight) relative to ground controls in the context of previously shown bone mineral density (BMD) loss that was observed in these flight groups. We demonstrate elevated abundance of Lactobacillus murinus and Dorea sp. during microgravity exposure relative to ground control through whole-genome sequencing and 16S rRNA analyses. Specific functionally assigned gene clusters of L. murinus and Dorea sp. capable of producing metabolites, lactic acid, leucine/isoleucine, and glutathione are enriched. These metabolites are elevated in the microgravity-exposed host serum as shown by liquid chromatography-tandem mass spectrometry (LC-MS/MS) metabolomic analysis. Along with BMD loss, ELISA reveals increases in osteocalcin and reductions in tartrate-resistant acid phosphatase 5b signifying additional loss of bone homeostasis in flight.

Obesity, cancer, and response to immune checkpoint inhibitors: Could the gut microbiota be the mechanistic link?

Immune checkpoint inhibitors (ICI) have deeply changed the therapeutic management of a broad spectrum of solid tumors. Recent observations showed that obese patients receiving ICIs might have better outcomes than those with normal weight, while obesity was historically associated with a worse prognosis in cancer patients. Of note, obesity is associated with alterations in the gut microbiome profile, which interacts with immune and inflammatory pathways, both at the systemic and intratumoral levels. As the influence of the gut microbiota on the response to ICI has been repeatedly reported, a specific gut microbiome profile in obese cancer patients may be involved in their better response to ICI. This review summarizes recent data on the interactions between obesity, gut microbiota, and ICIs. In addition, we highlight possible pathophysiological mechanisms supporting the hypothesis that gut microbiota could be one of the links between obesity and poor response to ICIs.

A nexus of dietary restriction and gut microbiota: Recent insights into metabolic health

In recent times, dietary restriction (DR) has received considerable attention for its promising effects on metabolism and longevity. Previous studies on DR have mainly focused on the health benefits produced by different restriction patterns, whereas comprehensive reviews of the role of gut microbiota during DR are limited. In this review, we discuss the effects of caloric restriction, fasting, protein restriction, and amino acid restriction from a microbiome perspective. Furthermore, the underlying mechanisms by which DR affects metabolic health by regulating intestinal homeostasis are summarized. Specifically, we reviewed the impacts of different DRs on specific gut microbiota. Additionally, we put forward the limitations of the current research and suggest the development of personalized microbes-directed DR for different populations and corresponding next-generation sequencing technologies for accurate microbiological analysis. DR effectively modulates the composition of the gut microbiota and microbial metabolites. In particular, DR markedly affects the rhythmic oscillation of microbes which may be related to the circadian clock system. Moreover, increasing evidence supports that DR profoundly improves metabolic syndrome, inflammatory bowel disease, and cognitive impairment. To summarize, DR may be an effective and executable dietary manipulation strategy for maintaining metabolic health, however, further investigation is needed to elucidate the underlying mechanisms.

Soda intake influences phenotype, antioxidants and inflammatory status in high protein-fed wistar rats

An increasing population of people, especially young adults who exercise, consume high protein diets along with carbonated drinks. While there are numerous studies on the effect of high protein diets, there is a need to understand how protein diets in combination with carbonated drinks impact physiology. In order to assess these effects on wistar rats' phenotype, antioxidants and inflammatory profiles, 64 wistar rats were divided into dietary groups of 8 male and 8 female animals each. The animals were fed standard diet as control (chow), chow and carbonated soda, a high protein diet (48.1% energy from protein) and a high protein diet with carbonated soda according to their groups. Body measurements, blood glucose levels, serum insulin levels, lipid peroxidation, antioxidant activity, adipokines and inflammatory markers concentrations were all determined. At the end of the study, body measurements, inflammatory markers and adipokine concentration were increased in animals fed the high protein diet and high protein-soda diet. There was a decrease in antioxidant and lipid peroxidation levels in protein fed male and female animals but those fed protein in combination with soda had increased lipid peroxidation levels. In conclusion, high protein diet in combination with carbonated soda impacts physiology differently from a high protein diet alone, and may stimulate weight gain, oxidative stress and HPD-related inflammation in Wistar rats.

Links between Diet, Intestinal Anaerobes, Microbial Metabolites and Health

A dense microbial community resides in the human colon, with considerable inter-individual variability in composition, although some species are relatively dominant and widespread in healthy individuals. In disease conditions, there is often a reduction in microbial diversity and perturbations in the composition of the microbiota. Dietary complex carbohydrates that reach the large intestine are important modulators of the composition of the microbiota and their primary metabolic outputs. Specialist gut bacteria may also transform plant phenolics to form a spectrum of products possessing antioxidant and anti-inflammatory activities. Consumption of diets high in animal protein and fat may lead to the formation of potentially deleterious microbial products, including nitroso compounds, hydrogen sulphide, and trimethylamine. Gut anaerobes also form a range of secondary metabolites, including polyketides that may possess antimicrobial activity and thus contribute to microbe-microbe interactions within the colon. The overall metabolic outputs of colonic microbes are derived from an intricate network of microbial metabolic pathways and interactions; however, much still needs to be learnt about the subtleties of these complex networks. In this review we consider the multi-faceted relationships between inter-individual microbiota variation, diet, and health.

Assessing the per Capita Food Supply Trends of 38 OECD Countries between 2000 and 2019-A Joinpoint Regression Analysis

Food supply has an impact on the prevalence of diet-related non-communicable diseases. We aimed to analyze the protein, fat (g/capita/day) and calorie (kcal/capita/day) supply from 2000 to 2019 as derived from the OECD Health Statistics database. A joinpoint regression was used to examine the number and location of breakpoints in the time series. The annual percent change (APC) was calculated using Joinpoint 4.9.0.0. The per capita daily kcal per nutrient was calculated for each country and the resulting percentage distributions were compared to the acceptable macronutrient distribution ranges. Protein, fat and calorie supplies have increased significantly between 2000 and 2019. Each started to show a much steeper, positive change between 2012 and 2014 (APC_fat: 1.0; 95%CI: 0.8-1.1; APC_protein: 0.5; 95%CI: 0.3-0.6; APC_kcal: 0.4; 95%CI: 0.3-0.5). In terms of the composition of the daily calorie intake per capita, the overall share of fat (+4.9%) and protein (+1.0%) increased between 2000 and 2019. We found significant differences among countries and also an increasing and optimal proportion of consumed protein per total calorie in all countries over the last two decades. We concluded that several countries have access to fat availability above the optimal level, which deserves particular attention from health policy makers in the fight against obesity and diet-related diseases.

Efficacy of low carbohydrate and ketogenic diets in treating mood and anxiety disorders: systematic review and implications for clinical practice

BACKGROUND

There is mounting interest in the potential efficacy of low carbohydrate and very low carbohydrate ketogenic diets in various neurological and psychiatric disorders.

AIMS

To conduct a systematic review and narrative synthesis of low carbohydrate and ketogenic diets (LC/KD) in adults with mood and anxiety disorders.

METHOD

MEDLINE, Embase, PsycINFO and Cochrane databases were systematically searched for articles from inception to 6 September 2022. Studies that included adults with any mood or anxiety disorder treated with a low carbohydrate or ketogenic intervention, reporting effects on mood or anxiety symptoms were eligible for inclusion. PROSPERO registration CRD42019116367.

RESULTS

The search yielded 1377 articles, of which 48 were assessed for full-text eligibility. Twelve heterogeneous studies (stated as ketogenic interventions, albeit with incomplete carbohydrate reporting and measurements of ketosis; diet duration: 2 weeks to 3 years; n = 389; age range 19 to 75 years) were included in the final analysis. This included nine case reports, two cohort studies and one observational study. Data quality was variable, with no high-quality evidence identified. Efficacy, adverse effects and discontinuation rates were not systematically reported. There was some evidence for efficacy of ketogenic diets in those with bipolar disorder, schizoaffective disorder and possibly unipolar depression/anxiety. Relapse after discontinuation of the diet was reported in some individuals.

CONCLUSIONS

Although there is no high-quality evidence of LC/KD efficacy in mood or anxiety disorders, several uncontrolled studies suggest possible beneficial effects. Robust studies are now needed to demonstrate efficacy, to identify clinical groups who may benefit and whether a ketogenic diet (beyond low carbohydrate) is required and to characterise adverse effects and the risk of relapse after diet discontinuation.

Oral supplementation of nicotinamide riboside alters intestinal microbial composition in rats and mice, but not humans

The gut microbiota impacts systemic levels of multiple metabolites including NAD⁺ precursors through diverse pathways. Nicotinamide riboside (NR) is an NAD⁺ precursor capable of regulating mammalian cellular metabolism. Some bacterial families express the NR-specific transporter, PnuC. We hypothesized that dietary NR supplementation would modify the gut microbiota across intestinal sections. We determined the effects of 12 weeks of NR supplementation on the microbiota composition of intestinal segments of high-fat diet-fed (HFD) rats. We also explored the effects of 12 weeks of NR supplementation on the gut microbiota in humans and mice. In rats, NR reduced fat mass and tended to decrease body weight. Interestingly, NR increased fat and energy absorption but only in HFD-fed rats. Moreover, 16S rRNA gene sequencing analysis of intestinal and fecal samples revealed an increased abundance of species within Erysipelotrichaceae and Ruminococcaceae families in response to NR. PnuC-positive bacterial strains within these families showed an increased growth rate when supplemented with NR. The abundance of species within the Lachnospiraceae family decreased in response to HFD irrespective of NR. Alpha and beta diversity and bacterial composition of the human fecal microbiota were unaltered by NR, but in mice, the fecal abundance of species within Lachnospiraceae increased while abundances of Parasutterella and Bacteroides dorei species decreased in response to NR. In conclusion, oral NR altered the gut microbiota in rats and mice, but not in humans. In addition, NR attenuated body fat mass gain in rats, and increased fat and energy absorption in the HFD context.