Review article: short chain fatty acids as potential therapeutic agents in human gastrointestinal and inflammatory disorders

Interkingdom signaling between gastrointestinal hormones and the gut microbiome

The interplay between the gut microbiota and gastrointestinal hormones plays a pivotal role in the health of the host and the development of diseases. As a vital component of the intestinal microecosystem, the gut microbiota influences the synthesis and release of many gastrointestinal hormones through mechanisms such as modulating the intestinal environment, producing metabolites, impacting mucosal barriers, generating immune and inflammatory responses, and releasing neurotransmitters. Conversely, gastrointestinal hormones exert feedback regulation on the gut microbiota by modulating the intestinal environment, nutrient absorption and utilization, and the bacterial biological behavior and composition. The distributions of the gut microbiota and gastrointestinal hormones are anatomically intertwined, and close interactions between the gut microbiota and gastrointestinal hormones are crucial for maintaining gastrointestinal homeostasis. Interventions leveraging the interplay between the gut microbiota and gastrointestinal hormones have been employed in the clinical management of metabolic diseases and inflammatory bowel diseases, such as bariatric surgery and fecal microbiota transplantation, offering promising targets for the treatment of dysbiosis-related diseases.

Potential of fermented foods and their metabolites in improving gut microbiota function and lowering gastrointestinal inflammation

Foods prepared using microbial conversion of major and minor food components, which are otherwise known as fermented foods continue to impact human health. The live microorganisms and transformed metabolites can also have a deep influence on the gut microbiota, the multifaceted population of microorganisms dwelling inside the gut play a key role in wellbeing of an individual. The probiotic strains delivered through the consumption of fermented food and other bioactive components such as polyphenolic metabolites, bioactive peptides, short-chain fatty acids and others including those produced via gut microbiota mediated transformations have been proposed to balance the gut microbiota diversity and activity, and also to regulate the inflammation in the gut. However, little is known about such effects and only a handful of fermented foods have been explored to date. We herein review the recent knowledge on the dysbiotic gut microbiota linking to major gut inflammatory diseases. Also, evidences that fermented food consumption modulates the gut microbiota, and its impact on the gut inflammation and inflammatory diseases have been discussed. © 2024 Society of Chemical Industry.

Polysaccharides of Melientha longistaminea regulates immune function and gut microbiota in cyclophosphamide (CTX)-induced immunosuppressed mice

MLS is a bioactive extract of Melientha longistaminea shoots. In this study, we characterized the preliminary structure of MLS. And establish in vivo immune model experiments. To investigate the potential mechanism of immunomodulatory effects on CTX-induced immunosuppressed mice. From the experimental results, we found that MLS restored immune organ damage in immunosuppressed mice, increased cytokine and immunoglobulin secretion in the spleen, and attenuated oxidative damage to the liver by CTX. Meanwhile, MLS was also effective in ameliorating immune injury in immunosuppressed mice by activating the NF-κB and Nrf2 signaling pathways. MLS effectively improved the composition of the gut flora and increased the production of SCFAs in the gut. The results indicate that MLS has immunomodulatory effects and provides a research basis for developing Melientha longistaminea polysaccharides as immunomodulatory adjuvants.

Gut-Heart Axis: The Role of Gut Microbiota and Metabolites in Heart Failure

Heart failure is a global health issue with significant mortality and morbidity. There is increasing evidence that alterations in the gastrointestinal microbiome, gut epithelial permeability, and gastrointestinal disorders contribute to heart failure progression through various pathways, including systemic inflammation, metabolic dysregulation, and modulation of cardiac function. Moreover, several medications used to treat heart failure directly impact the microbiome. The relationship between the gastrointestinal tract and the heart is bidirectional, termed the gut-heart axis. It is increasingly understood that diet-derived microbial metabolites are key mechanistic drivers of the gut-heart axis. This includes, for example, trimethylamine N-oxide and short-chain fatty acids. This review discusses current insights into the interplay between heart failure, its associated risk factors, and the gut microbiome, focusing on key metabolic pathways, the role of dietary interventions, and the potential for gut-targeted therapies. Understanding these complex interactions could pave the way for novel strategies to mitigate heart failure progression and improve patient outcomes.

Gut Microbiome Signature in Predisease Phase of Inflammatory Bowel Disease: Prediction to Pathogenesis to Prevention

Advances in understanding the pathogenesis of inflammatory bowel disease (IBD) point toward a key role of the gut microbiome. We review the data describing the changes in the gut microbiome from IBD case-control studies and compare these findings with emerging data from studies of the preclinical phase of IBD. What is apparent is that assessing changes in the composition and function of the gut microbiome during the preclinical phase helps address confounding factors, such as disease activity and drug therapy, which can directly influence the gut microbiome. Understanding these changes in the predisease phase provides a means of predicting IBD in high-risk populations and offers insights into possible mechanisms involved in disease pathogenesis. Finally, we discuss strategies to use this information to design interventions aimed at modulating the microbiome as a means of preventing or delaying the onset of IBD.

Effects of high-dose glucocorticoids on gut microbiota in the treatment of Graves' ophthalmopathy

Many studies indicate the gut microbiome is associated with diseases caused by administering high-dose glucocorticoids (GCs), such as hypertension, hyperglycemia, and osteoporosis. However, the association between intestinal flora and the use of high-dose GCs remains elusive. We aimed to characterize gut microbiome in Graves' ophthalmopathy (GO) patients after administering high-dose GCs. In this study, 20 primary GO patients were recruited. The differences in gut microbiota of GO patients before and after administering high-dose GCs were analyzed by 16S rDNA sequencing technology. Untargeted metabolomic analysis was used to examine the differences in gut metabolites between two groups. There were significant differences in α and β diversities of gut microbiota in GO patients before and after administering high-dose GCs. The random forest analysis indicated that three intestinal bacteria (Faecalibacterium, Streptococcus, and Prevotella) could distinguish the two groups with the highest accuracy, which was proven by receiver operator characteristic curve and linear discriminant analysis effect size analysis. The short-chain fatty acid-producing ability in GO patients' gut after high-dose GC administration was significantly decreased. The 5-hydroxytryptamine levels significantly increased in the gut of GO patients after administering high-dose GCs. Our study suggests that high-dose GC administration causes the changes in gut microbiome and metabolites. Moreover, the altered flora and metabolites are related to hypertension, hyperglycemia, and osteoporosis. These findings can help understand the development of side effects caused by high-dose GCs and can be further used to develop potential probiotics to facilitate the prevention for those side effects.IMPORTANCEFor the first time, we revealed that gut microbiome and metabolome in Graves' ophthalmopathy patients after high-dose glucocorticoid (GC) administration significantly changed, and the altered flora and metabolites are related to hypertension, hyperglycemia, and osteoporosis. These findings can help understand the development of side effects caused by high-dose GCs and can be further used to develop potential probiotics to facilitate the prevention for those side effects.

Comparative analysis of gut microbiome-derived short-chain fatty acids in patients with severe mental disorder: Insights from schizophrenia and bipolar disorder

Both schizophrenia (SZ) and bipolar disorder (BD) are associated with disruptions in the gut microbiome. Short-chain fatty acids (SCFAs), such as acetate, propionate and butyrate, are key metabolites produced by gut bacteria that influence brain function, immune responses and behaviour. We conducted a cross-sectional observational study with 123 patients (86 with SZ and 37 with BD). We analysed faecal samples for SCFA and examined associations with clinical (psychopathology and cognition), metabolic and lifestyle factors. We performed analysis of covariance to find differences in SCFA levels between diagnostic groups, adjusting for covariates. Faecal SCFA levels were numerically higher in the SZ group than in the BD group. However, after adjusting for covariates, a significant sex-by-diagnosis interaction was observed only for acetate levels. Body mass index emerged as a key predictor of SCFA levels but we observed no significant associations with other metabolic or lifestyle variables, including diet, physical activity and blood inflammatory biomarkers. Additionally, SCFA levels showed no correlation with symptom severity or cognitive performance in either group. This study is the first to compare SCFA profiles between SZ and BD, highlighting potential differences in gut microbiota-derived metabolites between these disorders. These findings suggest greater disruption of the gut-brain axis in SZ, potentially reflecting distinct pathophysiological mechanisms involving metabolic and sex-related factors. Further research, including blood SCFA measurements, could better explain the role of SCFAs and explore microbiota-targeted therapeutic strategies for SZ and BD.

Comparative Study on the Effects of Selenium-Enriched Yeasts with Different Selenomethionine Contents on Gut Microbiota and Metabolites

Selenium is an essential trace element for human health, but it mainly exists in an inorganic form that cannot be directly absorbed by the body. Brewer's yeast efficiently converts inorganic selenium into bioavailable organic selenium, making selenium-enriched yeast highly significant for human health research. Selenomethionine (SeM) is an important indicator for evaluating the quality of selenium-enriched yeast. Brewer's yeast was selected as the experimental subject, and the digestion of this yeast (Brewer's yeast) was simulated using an in vitro biomimetic gastrointestinal reactor to evaluate the effects of selenium-enriched yeast with various SeM levels on the gut flora of a healthy population. The experimental design comprised normal yeast (control group, OR), yeast containing moderate SeM levels (selenium-enriched group, SE), yeast containing high SeM levels (high-selenium group, MU), and a commercially available group comprising selenium-enriched yeast tablets (MA). The MU group exhibited a significantly higher concentration of short-chain fatty acids than the OR and MA groups during 48 h of fermentation, with significant differences observed (p < 0.05). Sequencing results revealed that the MU group showed significantly increased relative abundances of Bacteroidetes and Actinobacteria, while exhibiting a decreased ratio of Firmicutes to Bacteroidetes, which may simultaneously affect multiple metabolic pathways in vivo. These findings support the theory that selenium-enriched yeast with a high SeM has a more positive effect on human health compared with traditional yeast and offer new ideas for the development and application of selenium-enriched yeast.

Protective Effect of Dietary Fiber on Blood Pressure and Vascular Dysfunction Through Regulation of Sympathetic Tone and Immune Response in Genetic Hypertension

The mechanisms underlying the antihypertensive effect of dietary fibers remain poorly understood. This study investigates whether dietary fiber supplementation can prevent cardiovascular damage and high blood pressure in a genetic model of neurogenic hypertension. Six-week-old male spontaneously hypertensive rats (SHR) and their respective normotensive control, Wistar Kyoto rats (WKY), were divided into four groups: Untreated WKY, untreated SHR, SHR treated with resistant starch (SHR + RS), and SHR treated with inulin-type fructans (SHR + ITF) for 12 weeks. Additionally, a faecal microbiota transplantation (FMT) experiment was conducted, transferring faecal content from treated SHR donors to recipient SHRs. A diet rich in RS fiber reduced vascular oxidative stress, inflammation, and high blood pressure. These protective effects were associated with a reshaped gut microbiota, leading to increased short-chain fatty acid production, reduced endotoxemia, decreased sympathetic activity, and a restored balance between Th17 and Treg lymphocytes in mesenteric lymph nodes and aorta. Elevated plasma levels of acetate and butyrate in the SHR + RS group correlated with increased expression of aortic GPR41, GRP43 and PPARδ. Conversely, ITF treatment failed to prevent hypertension or endothelial dysfunction in SHR. FMT from the SHR + RS group to recipient SHR partially replicated these beneficial effects. This study highlights the antihypertensive benefits of dietary insoluble RS fiber, which are attributed to enhanced short-chain fatty acids production in the gut. This leads to improved gut permeability, reduced sympathetic tone, and diminished vascular T-cell accumulation. Therefore, dietary interventions with RS fiber may offer promising therapeutic strategies for preventing hypertension.

Safety Assessment of Butyric Acid-Rich Triglyceride Oil: A Novel Palatable Formulation of Butyrate for the Pediatric Population

A novel, palatable butyric acid-rich triglyceride oil has been developed and is available as a food supplement for adults in the United States and Canada. A program of safety studies was conducted with butyric acid-rich triglyceride oil for the pediatric population. The oil was tested in a microbial reverse mutation assay Ames Test OECD471 (Organisation for Economic Co-operation and Development) in which all bacterial strains showed negative responses over the complete dose range in two independently repeated experiments. All values were within the laboratory historical control data ranges. Further, data from the human lymphocyte micronucleus assay (OECD487) in the presence or absence of a metabolic activator (S9-mix), the oil did not induce a biologically relevant increase in the number of binucleated cells with micronuclei; therefore, the oil is considered not to be clastogenic or aneugenic. In a 90-day rat repeat dose toxicity study (OECD408), there were no unscheduled deaths, no treatment-related clinical signs, or effects on body weight and body weight gain, food consumption, ophthalmology, FOB parameters (including motor activity), clinical chemistry including thyroid hormones, and sperm parameters. There were no related organ weight changes, macroscopic or microscopic findings. In an extended one-generation reproductive toxicology study (EOGRTS) OECD443, there were no biologically important changes in body weight or body weight gain observed in the P generation male rats during the dosing period. At the end of the dosing period, the mean body weights in the male rats were 98% and 98% of the control group value in the 3720 and 4650 mg/kg/day dose groups, respectively. No biologically important changes in maternal body weights or body weight gains were observed during the premating, gestation, or lactation periods at dose levels up to and including 4650 mg/kg/day. Clinical signs observed in the P generation males and females were within the historical data ranges and not test substance related. There were no test substance-related changes in any other tested outcomes analyzed in the P generation males and females at doses up to and including 4650 mg/kg/day. In the F1 Generation, preweaning clinical signs observed in the males and females were within the historical data ranges and not test article related. There were no statistically significant or biologically relevant abnormalities in any of the parameters analyzed throughout the preweaning period at maternal dose levels up to and including 4650 mg/kg/day. In the postweaning period, there were also no clinical signs observed in males and females; all were within the historical data ranges and not test article related. There were no statistically significant or biologically relevant abnormalities in any of the parameters analyzed throughout the postweaning period at maternal dose levels up to and including 4650 mg/kg/day including body weights. Taken together, data from these toxicity studies show that butyric acid-rich triglyceride oil is extremely safe with a "no observed adverse effect level" (NOAEL) considered to be 4650 mg/kg/day, the highest dose tested.

Contributions of Dietary Patterns and Factors to Regulation of Rheumatoid Disease

Rheumatoid arthritis (RA) is a systemic autoimmune disease that commonly causes pain in joints and the progressive destruction of cartilage and bone, which significantly reduces the quality of life and increases the social burden. However, there is still no cure for RA, so it is highly important to explore additional adjuvant treatment methods. Studies have indicated that malnutrition, changes in intestinal microbiota, and changes in immune status caused by dietary imbalance are directly related to the onset of RA, indicating that dietary intervention may offer a simple, economical, and practical avenue to relieve RA. Therefore, in this review, we discuss the pathogenesis of RA and summarize the influence of different dietary patterns on RA. In particular, we pointed out that high-fat, high-sugar, and high-salt diets contribute to RA progression, whereas the Mediterranean diet (MD) is beneficial for preventing RA. Furthermore, the ingredients of food, such as dietary fiber, probiotics, and vitamins, help reduce the level of inflammation and relieve joint pain, which may play critical roles in the treatment of RA. Therefore, dietary intervention provides a potential effective approach for adjuvant therapy of RA.

Short-chain fatty acids in viral infection: the underlying mechanisms, opportunities, and challenges

Viral infections can cause cellular pathway derangements, cell death, and immunopathological responses, leading to host inflammation. Short-chain fatty acids (SCFAs), produced by the microbiota, have emerged as a potential therapeutic for viral infections due to their ability to modulate these processes. However, SCFAs have been reported to have both beneficial and detrimental effects, necessitating a comprehensive understanding of the underlying mechanisms. This review highlights the complex mechanisms underlying SCFAs' effects on viral infection outcomes. We also emphasize the importance of considering how SCFAs' activities may differ under diverse contexts, including but not limited to target cells with different metabolic wiring, different viral causes of infection, the target organism/cell's nutrient availability and/or energy balance, and hosts with varying microbiome compositions.

Targeting gut microbiota dysbiosis in inflammatory bowel disease: a systematic review of current evidence

Introduction

The dysbiosis of the gut microbiota has been identified as a central factor in the pathogenesis of inflammatory bowel disease (IBD), a chronic condition characterized by frequent recurrence and various adverse effects of traditional therapies. While treatments targeting the gut microbiota show promise, their efficacy in IBD management still requires extensive evaluation. Our systematic review analyzes recent studies to elucidate the advancements and challenges in treating IBD using microbial-based therapies.

Methods

Through a comprehensive systematic review spanning key scientific databases-PubMed, Embase, Cochrane, Web of Science, Scopus, and Google Scholar-we scrutinized the impact of probiotics, prebiotics, synbiotics, and fecal microbiota transplantation (FMT) on individuals with IBD. Our detailed analysis covered study and participant demographics, along with seven key outcome measures: disease activity index, inflammatory markers, serum cytokines, microbiome composition, adverse effects, and the rates of remission and relapse.

Results

From 6,080 initial search hits, we included 71 studies that assessed various interventions compared to placebo or standard medical therapy. Although there was notable variation in clinical results while assessing different outcomes, overall, probiotics, prebiotics, and synbiotics enhanced the success rates in inducing remission among IBD patients. Furthermore, we noted significant reductions in levels of pro-inflammatory markers and cytokines. Additionally, the requirement for steroids, hospitalization, and poor outcomes in endoscopic and histological scores were significantly reduced in individuals undergoing FMT.

Conclusion

Our investigation highlights the potential of targeting gut microbiota dysbiosis with microbial-based therapies in patients with IBD. We recommend conducting larger, placebo-controlled randomized trials with extended follow-up periods to thoroughly assess these treatments' clinical efficacy and safety before widespread recommendations for clinical application.

Gut Microbiota Metabolites Sensed by Host GPR41/43 Protect Against Hypertension

BACKGROUND

Fermentation of dietary fiber by the gut microbiota leads to the production of metabolites called short-chain fatty acids, which lower blood pressure and exert cardioprotective effects. Short-chain fatty acids activate host signaling responses via the functionally redundant receptors GPR41 (G-protein-coupled receptor 41) and GPR43 (G-protein-coupled receptor 43), which are highly expressed by immune cells. Whether and how these receptors protect against hypertension or mediate the cardioprotective effects of dietary fiber remains unknown.

METHODS

Cardiovascular phenotype was assessed in untreated and Ang II (angiotensin II) treated hypertensive wild-type and GPR41/43 knockout (KO) double knockout male mice fed diets with different levels of fiber content. Some mice received TLR4 (toll-like receptor 4)-antagonist treatment and bone marrow chimeras. SNPs (single-nucleotide polymorphisms) associated with GPR41 and GPR43 expression were assessed in UK Biobank participants.

RESULTS

Untreated GPR41/43KO mice had unaltered blood pressure but had greater cardiac and renal collagen deposition with higher macrophage numbers in the kidney compared with wild-type mice. Ang II-treated GPR41/43KO mice showed higher systolic blood pressure, cardiorenal weights and collagen deposition, and increased gut permeability, which allows the translocation of gastrointestinal bacterial components such as lipopolysaccharides into the circulation. The use of an antagonist to the lipopolysaccharide receptor, TLR4, a potent proinflammatory signaling molecule, restored the cardiovascular phenotype in GPR41/43KO mice. The lack of GPR41/43 expression in the immune compartment was sufficient to lead to a worsened hypertensive phenotype. We also demonstrate that GPR41/43 is, at least partially, responsible for the blood pressure-lowering and cardioprotective effects of a high-fiber diet. Finally, using the UK Biobank, we provide translational evidence that variants associated with lower expression of both GPR41 and GPR43 are more prevalent in participants with hypertension.

CONCLUSIONS

Our findings highlight that lack of short-chain fatty acid-receptor signaling via both GPR41 and GPR43 increases risk of high blood pressure, suggesting treatments that target these receptors could be a novel strategy to prevent or treat hypertension.

The effect of oral synbiotics on the gut microbiota and inflammatory biomarkers in healthy adults: a systematic review and meta-analysis

CONTEXT

Prior research has explored the effect of synbiotics, the combination of probiotics and prebiotics, on the gut microbiota in clinical populations. However, evidence related to the effect of synbiotics on the gut microbiota in healthy adults has not been reviewed to date.

OBJECTIVE

A systematic review and meta-analysis was conducted to comprehensively investigate the effect of synbiotics on the gut microbiota and inflammatory markers in populations of healthy adults.

DATA SOURCES

Scopus, PubMed, Web of Science, ScienceDirect, MEDLINE, CINAHL, and The Cochrane Library were systematically searched to retrieve randomized controlled trials examining the primary outcome of gut microbiota or intestinal permeability changes after synbiotic consumption in healthy adults. Secondary outcomes of interest were short-chain fatty acids, inflammatory biomarkers, and gut microbiota diversity.

DATA EXTRACTION

Weighted (WMD) or standardized mean difference (SMD) outcome data were pooled in restricted maximum likelihood models using random effects. Twenty-seven articles reporting on 26 studies met the eligibility criteria (n = 1319).

DATA ANALYSIS

Meta-analyses of 16 studies showed synbiotics resulted in a significant increase in Lactobacillus cell count (SMD, 0.74; 95% confidence interval [CI], 0.15, 1.33; P = 0.01) and propionate concentration (SMD, 0.22; 95% CI, 0.02, 0.43; P = 0.03) compared with controls. A trend for an increase in Bifidobacterium relative abundance (WMD, 0.97; 95% CI, 0.42, 2.52; P = 0.10) and cell count (SMD, 0.82; 95% CI, 0.13, 1.88; P = 0.06) was seen. No significant differences in α-diversity, acetate, butyrate, zonulin, IL-6, CRP, or endotoxins were observed.

CONCLUSION

This review demonstrates that synbiotics modulate the gut microbiota by increasing Lactobacillus and propionate across various healthy adult populations, and may result in increased Bifidobacterium. Significant variations in synbiotic type, dose, and duration should be considered as limitations when applying findings to clinical practice.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO no. CRD42021284033.

Comparative analysis of intestinal microbiota and its function on digestion and immunity of juvenile abalone Haliotis discus hannai fed two different sources of dietary soybean protein

The present study evaluated the replacement of fish meal (FM) with two different soybean protein sources (soybean protein concentrate (SPC) and soybean meal (SBM)) on the intestine microbiota of abalone Haliotis discus hannai and the implications for the host intestinal function and health. The control diet with FM as the main protein source (CON), and the four experimental diets with 50 % and 100 % SBM replacing FM (SBM50 and SBM100), and 25 % and 100 % SPC replacing FM (SPC25 and SPC100) were fed to abalone for 110 days. The intestinal microbiota analysis results revealed that there were no significant differences in α-diversity indices (Chao1, Ace, Sobs, and Shannon) among all groups. However, analysis of similarity (ANOSIM) demonstrated dramatic shifts in the intestinal microbiota component at the genus level among the groups. Venn diagram analysis identified 470 overlapping operational taxonomic units (OTUs) across the five groups, with the SBM50 and CON groups exhibiting the highest and lowest number of unique OTUs, respectively. Firmicutes and Proteobacteria were the predominant phyla in abalone, with Mycoplasma being the dominant genus (CON: 42.95 %; SBM50: 23.98 %; SBM100: 49.32 %; SPC25: 27.20 %; SPC100: 34.25 %). Notably, the pathogens Vibrio abundance in the SPC25 group was significantly lower than in the CON group. The intestinal microbiota networks in the CON, SBM50, SBM100, SPC25, and SPC100 groups consisted of 1757, 2140, 1992, 2281 and 1747 edges, respectively. Furthermore, correlation heatmap results suggested that digestive enzymes and immune indices in abalone were associated with specific intestinal microbiota. Functional prediction via the KEGG pathway analysis revealed that the replacement levels of dietary FM with SBM and SPC significantly affect various biological functions of the intestinal microbiota. In summary, feeding SBM (50 %) and SPC (25 %) diets to abalone increased the abundance of beneficial bacterium in the intestines, contributing to improved digestion and increased growth rate of abalone.

Leaky Gut Syndrome: An Interplay Between Nutrients and Dysbiosis

PURPOSE OF REVIEW

The gut microbiota (GM) is directly related to health and disease. In this context, disturbances resulting from excessive stress, unbalanced diet, alcohol abuse, and antibiotic use, among other factors, can contribute to microbiota imbalance, with significant impacts on host health. This review provides a comprehensive examination of the literature on the influence of diet on dysbiosis and increased intestinal permeability over the past five years.

RECENT FINDINGS

Diet can be considered one of the main modulating factors of GM, impacting its composition and functionality. Excessive consumption of simple carbohydrates, saturated fats, and processed foods appears to be directly linked to dysbiosis, which can lead to intestinal hyperpermeability and leaky gut syndrome. On the other hand, diets primarily composed of food groups such as nuts, vegetables, fruits, fish, and poultry in moderate quantities, along with limited consumption of red and processed meats, are associated with a more diverse, healthier, and beneficial GM for the host. It is worth noticing that the use of prebiotics and probiotics, omega-3 supplementation, polyunsaturated fatty acids, and vitamins A, B, C, D, and E can positively modulate the intestinal microbiota by altering its metabolic activity, microbial composition, and improve intestinal barrier function. This review points to a new perspective regarding individualized dietary intervention and the need to integrate it into several aspects of cellular biology, biochemistry, and microbiology to prescribe more effective diets and thus contribute to patients' comprehensive health.

Screening of the effect of new food prototypes based on fermented lentil and quinoa flours on the colonic microbiota of older adults through a static in vitro colonic fermentation model

In view of the increasing demand for plant-based protein alternatives, along with the increased protein requirements of older adults, the formulation of new food concepts based on protein-rich ingredients from legumes or pseudo-cereals seems a promising approach. Previous studies have found that solid-state fermentation can improve the nutritional value and digestibility of plant-based commodities; however, scarce evidence exists regarding the effect on prebiotic potential. This study aimed to compare the effect of fermented and unfermented quinoa and lentil flours on the colonic microbiota, as well as that of new food prototypes (gels and breads) made with the flours. After simulating static colonic fermentation of the substrates by using a pool faecal inoculum obtained from four older adults, the microbiota composition (16S rRNA gene sequencing) and short-chain fatty acids (SCFA, gas chromatography GC-FID) were determined. The results showed statistically significant changes in the microbiota at the genus taxonomic level in the range of -5.8% to +17.6% relative abundance. Common findings in all experiments were increased Bacteroides, Acidaminococcus and Parabacteroides and decreased Asteroleplasma, Oscillospiraceae UCG-002 group and Alistipes, as well as increased SCFA production. Overall, the food matrix (flour, gel or bread) was the variable that most affected the changes in the microbiota composition and diversity, while the impact of fermentation of the lentils or quinoa was not statistically significant for most cases. Concretely, the gel-like prototypes produced the most beneficial changes in microbiota composition, while the bread-like formulations were more favourable for increased SCFA and decreased bSCFA production. In conclusion, new food prototypes based on lentil and quinoa flour could have beneficial prebiotic potential. However, few additional advantages were observed from previous solid-state fermentation for obtaining the fermented lentils and quinoa flour.

Oral Supplements of Combined Lactobacillus plantarum and Asparagus officinalis Modulate Gut Microbiota and Alleviate High-Fat Diet-Induced Cognitive Deficits and Neurodegeneration in Rats

High-fat diet (HFD) consumption disrupts the gut microbiome, instigating metabolic disturbance, brain pathology, and cognitive decline via the gut-brain axis. Probiotic and prebiotic supplementation have been found to improve gut microbiome health, suggesting they could be effective in managing neurodegenerative disorders. This study explored the potential benefits of the probiotic strain Lactobacillus plantarum 20174 (L. plantarum), prebiotic Asparagus officinalis (A. officinalis) extract, or their synbiotic combination against HFD-induced cognitive dysfunction and neurodegeneration in rats. Male Sprague-Dawley rats were fed either a normal diet or an HFD for 24 weeks. Starting from week 13, rats on either diet were divided into vehicle-, prebiotic-, probiotic-, and synbiotic-treated subgroups. Rats received their assigned intervention for 12 more weeks. Prebiotic, probiotic, or synbiotic treatment reverted HFD-instigated alterations in hippocampal amyloid beta, p-tau, α-synuclein, and BDNF levels, leading to restored cognitive function. The tested therapies also improved the HFD-disrupted lipid profile. Interestingly, probiotic and synbiotic therapies attenuated oxidative stress and inflammation, reinstated neurotransmitter balance, and mitigated the energy deficit in HFD-fed rats. Furthermore, L. plantarum and Asparagus administration modulated gut microbiota composition by raising Lactobacillus species and reducing Coliform and Staphylococci bacteria as well as fungi populations. These findings suggest that the oral consumption of A. officinalis prebiotics and/or L. plantarum probiotics alleviates HFD-induced cognitive deficit and neurodegeneration through modulation of the gut-brain axis with superior restorative effects being achieved by synbiotic treatment.

Yellow bean (Phaseolus vulgaris L.) germplasm with less dietary fiber have shorter cooking times and more bioavailable iron

Some yellow-colored market classes of dry bean (Phaseolus vulgaris L.) are valued by consumers as an easy-to-digest, fast cooking alternative to darker colored red and black beans, which in comparison generally have longer cooking times and reduced iron bioavailability. There is evidence that the cooking time of yellow beans is linked to the dietary fiber content and may also contribute to nutrient digestibility and bioavailability. Therefore, 52 fast-, moderate-, and slow-cooking yellow beans with diverse iron bioavailability from five market classes (Amarillo, Canario, Green-yellow, Manteca, and Mayocoba) were selected for total dietary fiber (TDF) analysis. TDF was measured as insoluble (IDF) + soluble (SDF) + oligosaccharides (OLIGO) using method AOAC2011.25. Wide variations in the concentrations of IDF (16.0-23.1%), SDF (1.6-7.7%), OLIGO (1.5-3.4%), and TDF (20.6-31.3%) were detected among the yellow beans with various cooking times. Lower concentrations of IDF in yellow beans were associated with shorter cooking times and higher iron bioavailability. The larger sized Andean yellow beans had more SDF than Middle American. One Mayocoba breeding line from Puerto Rico, PR1146-124, had 42% less OLIGOs than average, and may be useful for breeding low-flatulence beans for consumer acceptability. Fast cooking yellow beans provide the same SDF and OLIGO concentrations as yellow beans with longer cooking times but have the added benefit of shorter cooking times (convenience) and provide more bioavailable iron after cooking.

Gut physiology and environment explain variations in human gut microbiome composition and metabolism

The human gut microbiome is highly personal. However, the contribution of gut physiology and environment to variations in the gut microbiome remains understudied. Here we performed an observational trial using multi-omics to profile microbiome composition and metabolism in 61 healthy adults for 9 consecutive days. We assessed day-to-day changes in gut environmental factors and measured whole-gut and segmental intestinal transit time and pH using a wireless motility capsule in a subset of 50 individuals. We observed substantial daily fluctuations, with intra-individual variations in gut microbiome and metabolism associated with changes in stool moisture and faecal pH, and inter-individual variations accounted for by whole-gut and segmental transit times and pH. Metabolites derived from microbial carbohydrate fermentation correlated negatively with the gut passage time and pH, while proteolytic metabolites and breath methane showed a positive correlation. Finally, we identified associations between segmental transit time/pH and coffee-, diet-, host- and microbial-derived metabolites. Our work suggests that gut physiology and environment are key to understanding the individuality of the human gut microbial composition and metabolism.

Construction of biopolymer-based hydrogel beads for encapsulation, retention, and colonic delivery of tributyrin: Development of functional beverages (fortified bubble tea)

Tributyrin (TB) can be hydrolyzed into short chain fatty acids (butyric acid) in the gastrointestinal tract, which are claimed to exhibit beneficial health effects in the colon. However, digestion of tributyrin in the stomach and small intestine may promote its absorption in the upper gastrointestinal tract, thereby reducing its potential colonic health benefits. In this study, we therefore developed a novel method of encapsulating emulsified tributyrin within biopolymer-based hydrogel beads (≈ 800 μm) that were then encapsulated inside the boba beads (≈ 8-10 mm) found in bubble tea. The hydrogel beads were designed to retain and protect the tributyrin under upper gastrointestinal tract (GIT) conditions, but then release it within the colon. The concentration of tributyrin within the boba beads was 33.3 mg/g, which is above the value reported to exhibit health benefits. The morphology, encapsulation properties, water holding capacity, stability, and swelling properties of the tributyrin-loaded boba beads were characterized. Tapioca-based beads exhibited a larger degree of swelling when incubated in water for 12h (>95 %), whereas agar-based beads did not (< 20 %). In addition, the potential gastrointestinal fate of both free and encapsulated tributyrin oil droplets was assessed using an in vitro digestion model. The free tributyrin oil droplets were almost completely hydrolyzed (103.2 %) by the end of the small intestine phase, whereas the tributyrin oil droplets encapsulated within the agar-based (29.4 %) or tapioca-based (40.3 %) boba beads were much more resistant to digestion. The tapioca-based beads were partially broken down as they passed through the simulated GIT, while the agar-based beads maintained their structural integrity. The tapioca-based beads were gradually broken down as they passed through the simulated GIT, while the agar-based ones maintained their structural integrity. Agar beads were also harder, more resilient, and chewier than the tapioca ones. Both types of boba beads tended to swell and disintegrate when heated to high temperatures (90 °C), with the effect being more pronounced for the agar beads. Overall, our results suggest that the agar-based boba beads had greater potential for the delivery of tributyrin to the colon than the tapioca-based ones. The recent popularity of bubble tea means that it may be a suitable vehicle for delivering bioactive food components, like functional lipids, vitamins, nutraceuticals, or probiotics.

Design strategies of polysaccharide, protein and lipid-based nano-delivery systems in improving the bioavailability of polyphenols and regulating gut homeostasis

Polyphenols are plant secondary metabolites that have attracted much attention due to their anti-inflammatory, antioxidant, and gut homeostasis promoting effects. However, food matrix interaction, poor solubility, and strong digestion and metabolism of polyphenols cause barriers to their absorption in the gastrointestinal tract, which further reduces bioavailability and limits polyphenols' application in the food industry. Nano-delivery systems composed of biocompatible macromolecules (polysaccharides, proteins and lipids) are an effective way to improve the bioavailability of polyphenols. Therefore, this review introduces the construction of biopolymer-based nano-delivery systems and their application in polyphenols, with emphasis on improving the solubility, stability, sustained release and intestinal targeting of polyphenols. In addition, there are possible positive effects of polyphenol-loaded nano-delivery systems on modulating gut microbiota and gut homeostasis, with particular emphasis on modulating intestinal inflammation, metabolic syndrome, and gut-brain axis. It is worth noting that the safety of bio-based nano-delivery systems still need to be further studied. In summary, the application of the bio-based nano-delivery system to deliver polyphenols provides insights for improving the bioavailability of polyphenols and for the treatment of potential diseases in the future.

Fiber intake and fiber intervention in depression and anxiety: a systematic review and meta-analysis of observational studies and randomized controlled trials

CONTEXT

Dietary fibers hold potential to influence depressive and anxiety outcomes by modulating the microbiota-gut-brain axis, which is increasingly recognized as an underlying factor in mental health maintenance.

OBJECTIVE

Evidence for the effects of fibers on depressive and anxiety outcomes remains unclear. To this end, a systematic literature review and a meta-analysis were conducted that included observational studies and randomized controlled trials (RCTs).

DATA SOURCES

The PubMed, Embase, CENTRAL, CINAHL, and PsychINFO databases were searched for eligible studies.

DATA EXTRACTION

Study screening and risk-of-bias assessment were conducted by 2 independent reviewers.

DATA ANALYSIS

Meta-analyses via random effects models were performed to examine the (1) association between fiber intake and depressive and anxiety outcomes in observational studies, and (2) effect of fiber intervention on depressive and anxiety outcomes compared with placebo in RCTs. A total of 181 405 participants were included in 23 observational studies. In cross-sectional studies, an inverse association was observed between fiber intake and depressive (Cohen's d effect size [d]: -0.11; 95% confidence interval [CI]: -0.16, -0.05) and anxiety (d = -0.25; 95%CI, -0.38, -0.12) outcomes. In longitudinal studies, there was an inverse association between fiber intake and depressive outcomes (d = -0.07; 95%CI, -0.11, -0.04). In total, 740 participants were included in 10 RCTs, all of whom used fiber supplements. Of note, only 1 RCT included individuals with a clinical diagnosis of depression. No difference was found between fiber supplementation and placebo for depressive (d = -0.47; 95%CI, -1.26, 0.31) or anxiety (d = -0.30; 95%CI, -0.67, 0.07) outcomes.

CONCLUSION

Although observational data suggest a potential benefit for higher fiber intake for depressive and anxiety outcomes, evidence from current RCTs does not support fiber supplementation for improving depressive or anxiety outcomes. More research, including RCTs in clinical populations and using a broad range of fibers, is needed.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42021274898.

The Interactions Between Diet and Gut Microbiota in Preventing Gestational Diabetes Mellitus: A Narrative Review

Recent studies have revealed that dysbiosis, defined as alterations in gut microbiota, plays an important role in the development and the progression of many non-communicable diseases, including metabolic disorders, such as type 2 diabetes mellitus and gestational diabetes mellitus (GDM). The high frequency of GDM makes this disorder an important public health issue, which needs to be addressed in order to reduce both the maternal and fetal complications that are frequently associated with this disease. The studies regarding the connections between gut dysbiosis and GDM are still in their early days, with new research continuously emerging. This narrative review seeks to outline the mechanisms through which a healthy diet that protects the gut microbiota is able to prevent the occurrence of GDM, thus providing medical nutritional therapeutic perspectives for the management of GDM.

Dietary legumes and gut microbiome: a comprehensive review

The gut microbiome plays a crucial role in human health, affecting metabolic, immune, and cognitive functions. While the impact of various dietary components on the microbiome is well-studied, the effect of legumes remains less explored. This review examines the influence of legume consumption on gut microbiome composition, diversity, and metabolite production, based on 10 human and 21 animal studies. Human studies showed mixed results, with some showing increased microbial diversity and others finding no significant changes. However, legume consumption was linked to increases in beneficial bacteria like Bifidobacterium and Faecalibacterium. Animal studies generally indicated enhanced microbial diversity and composition changes, though these varied by legume type and the host's health. Some studies highlighted legume-induced shifts in bacteria associated with better metabolic health. Overall, the review emphasizes the complexity of legume-microbiome interactions and the need for standardized methodologies and longitudinal studies. While legumes have the potential to positively affect the gut microbiome, the effects are nuanced and depend on context. Future research should investigate the long-term impacts of legume consumption on microbiome stability and its broader health implications, particularly for disease prevention and dietary strategies.

Gut microbiota in two chickens' breeds: Characteristics and dynamic changes

The gut microbiota has been demonstrated to play an important role in host immunity, metabolism, digestion, and growth. However, studies regarding the gut microbiota in Tibetan chickens remains scarce in comparison with other poultry breeds. Here, we investigated the gut microbial characteristics of Tibetan chickens and Arbor Acres broiler chickens (AA broiler chickens) and compare their gut microbial differences. For this purpose, we collected cecal samples from 10 Tibetan chickens and 10 AA broiler chickens for amplicon sequencing. Results indicated that Tibetan chickens exhibited higher gut microbial diversity and abundance compared with AA broiler chickens. Moreover, PCoA-based scatter plot analysis showed that the gut microbial structure of the both breeds was significantly different. Although the dominant bacterial phyla (Firmicutes, Firmicutes and Bacteroidota) of Tibetan chickens and AA broiler chickens were the same, the abundance of some bacterial phyla and genera changed significantly. Microbial taxonomic analysis indicated that the relative abundance of 876 genera of 20 phylum in Tibetan chickens increased significantly, while the relative abundance of 160 genera of 3 phyla decreased significantly compared with AA broiler chickens. In summary, these results indicated that there are significant differences in the gut microbiota between Tibetan chickens and AA broiler chickens. This is an important exploration of the gut microbial characteristics and distribution of Tibetan chickens. The findings may contribute to promoting the development of the Tibetan chicken's industry and reveal the adaptability of Tibetan chickens to the environment.

Unlocking the potential for microbiome-based therapeutics to address the sustainable development goal of good health and wellbeing

Recent years have witnessed major advances and an ever-growing list of healthcare applications for microbiome-based therapeutics. However, these advances have disproportionately targeted diseases common in high-income countries (HICs). Within low- to middle-income countries (LMIC), opportunities for microbiome-based therapeutics include sexual health epidemics, maternal health, early life mortality, malnutrition, vaccine response and infectious diseases. In this review we detail the advances that have been achieved in microbiome-based therapeutics for these areas of healthcare and identify where further work is required. Current efforts to characterise microbiomes from LMICs will aid in targeting and optimisation of therapeutics and preventative strategies specifically suited to the unmet needs within these populations. Once achieved, opportunities from disease treatment and improved treatment efficacy through to disease prevention and vector control can be effectively addressed using probiotics and live biotherapeutics. Together these strategies have the potential to increase individual health, overcome logistical challenges and reduce overall medical, individual, societal and economic costs.

Ulcerative colitis: molecular insights and intervention therapy

Ulcerative colitis (UC) is a chronic inflammatory bowel disease characterized by abdominal pain, diarrhea, rectal bleeding, and weight loss. The pathogenesis and treatment of UC remain key areas of research interest. Various factors, including genetic predisposition, immune dysregulation, and alterations in the gut microbiota, are believed to contribute to the pathogenesis of UC. Current treatments for UC include 5-aminosalicylic acids, corticosteroids, immunosuppressants, and biologics. However, study reported that the one-year clinical remission rate is only around 40%. It is necessary to prompt the exploration of new treatment modalities. Biologic therapies, such as anti-TNF-α monoclonal antibody and JAK inhibitor, primarily consist of small molecules targeting specific pathways, effectively inducing and maintaining remission. Given the significant role of the gut microbiota, research into intestinal microecologics, such as probiotics and prebiotics, and fecal microbiota transplantation (FMT) shows promising potential in UC treatment. Additionally, medicinal herbs, such as chili pepper and turmeric, used in complementary therapy have shown promising results in UC management. This article reviews recent findings on the mechanisms of UC, including genetic susceptibility, immune cell dynamics and cytokine regulation, and gut microbiota alterations. It also discusses current applications of biologic therapy, herbal therapy, microecologics, and FMT, along with their prospects and challenges.

Bifidogenic Effect of Human Milk Oligosaccharides on Pediatric IBD Fecal Microbiota

The prevalence of pediatric inflammatory bowel disease (pIBD) has been increasing over the last two decades. Yet, treatment strategies are still limited, in part due to the multifactorial nature of the disease and the complex interplay between genetic, environmental, dietary, immune, and gut microbial factors in its etiology. With their direct and indirect anti-inflammatory properties, human milk oligosaccharides (HMOs) are a promising treatment and management strategy for IBD. However, to date there are no insights into how HMOs may affect pIBD microbiota. Here, we compared the effects of 2'fucosyllactose (2'FL), difucosyllactose (DFL), 3'sialyllactose (3'SL), and blends thereof with fructooligosaccharide (FOS) on microbiota functionality (short- and branched-chain fatty acids, pH, and gas production) and composition (quantitative shallow shotgun sequencing) using fecal material from eight different pediatric Crohn's disease patients inoculated in the SIFR® technology. In general, all HMO treatments significantly increased total short-chain fatty acid production when compared with FOS, despite equal gas production. We found that 2'FL, either alone or in combination with DFL and 3'SL, exhibited a strong acetogenic and propiogenic effect, and 3'SL an acetogenic effect that surpassed the effects observed with FOS. No differences in overall community diversity between HMO- and FOS-treated pIBD microbiota were observed. There was, however, a stronger bifidogenic effect of 2'FL, 3'SL, 2'FL/DFL, and 2'FL/DFL + 3'SL when compared with FOS. In general, 3'SL and HMO blends enriched a broader species profile, including taxa with potentially anti-inflammatory properties, such as Faecalibacterium prausnitzii and Blautia species. This study suggests HMOs as a promising strategy to beneficially alter the gut microbial profile in pIBD.

The key to intestinal health: a review and perspective on food additives

In this review, we explore the effects of food additives on intestinal health. Food additives, such as preservatives, antioxidants and colorants, are widely used to improve food quality and extend shelf life. However, their effects on intestinal microecology May pose health risks. Starting from the basic functions of food additives and the importance of intestinal microecology, we analyze in detail how additives affect the diversity of intestinal flora, oxidative stress and immune responses. Additionally, we examine the association between food additives and intestinal disorders, including inflammatory bowel disease and irritable bowel syndrome, and how the timing, dosage, and individual differences affect the body's response to additives. We also assess the safety and regulatory policies of food additives and explore the potential of natural additives. Finally, we propose future research directions, emphasizing the refinement of risk assessment methods and the creation of safer, innovative additives.

Metabolic mediators: microbial-derived metabolites as key regulators of anti-tumor immunity, immunotherapy, and chemotherapy

The human microbiome has recently emerged as a focal point in cancer research, specifically in anti-tumor immunity, immunotherapy, and chemotherapy. This review explores microbial-derived metabolites, emphasizing their crucial roles in shaping fundamental aspects of cancer treatment. Metabolites such as short-chain fatty acids (SCFAs), Trimethylamine N-Oxide (TMAO), and Tryptophan Metabolites take the spotlight, underscoring their diverse origins and functions and their profound impact on the host immune system. The focus is on SCFAs' remarkable ability to modulate immune responses, reduce inflammation, and enhance anti-tumor immunity within the intricate tumor microenvironment (TME). The review critically evaluates TMAO, intricately tied to dietary choices and gut microbiota composition, assessing its implications for cancer susceptibility, progression, and immunosuppression. Additionally, the involvement of tryptophan and other amino acid metabolites in shaping immune responses is discussed, highlighting their influence on immune checkpoints, immunosuppression, and immunotherapy effectiveness. The examination extends to their dynamic interaction with chemotherapy, emphasizing the potential of microbial-derived metabolites to alter treatment protocols and optimize outcomes for cancer patients. A comprehensive understanding of their role in cancer therapy is attained by exploring their impacts on drug metabolism, therapeutic responses, and resistance development. In conclusion, this review underscores the pivotal contributions of microbial-derived metabolites in regulating anti-tumor immunity, immunotherapy responses, and chemotherapy outcomes. By illuminating the intricate interactions between these metabolites and cancer therapy, the article enhances our understanding of cancer biology, paving the way for the development of more effective treatment options in the ongoing battle against cancer.

Association Between Adherence to EAT-Lancet Diet and Risk of Hypertension: An 18-Year National Cohort Study in China

OBJECTIVE

The EAT-Lancet Commission has proposed an EAT-Lancet diet (ELD), also known as a planetary health diet (PHD), which is environmentally sustainable and promotes human health. However, the association between this diet and the risk of hypertension remains unclear. This study aimed to determine whether adherence to ELD was associated with a lower risk of hypertension.

METHODS

11,402 adults without hypertension at baseline from the China Health and Nutrition Survey were included. The PHD score was used to evaluate ELD adherence, with higher scores reflecting better compliance. Cox proportional hazards regression analysis was utilized to estimate the hazard ratio (HR) with a 95% confidence interval (CI). Additionally, a subgroup analysis was performed to identify the possible effect modifiers, and a mediation analysis was conducted to explore the mediation effects of anthropometric measurements on the association between ELD and hypertension.

RESULTS

A total of 3993 participants (35%) developed hypertension during 93,058 person-years of follow-up. In the covariate-adjusted model, hypertension risk was reduced in the highest quartile participants compared to the lowest quartile of the PHD score (adjusted HR: 0.79, 95%CI: 0.71-0.87; P-trend < 0.001), which remained significant after sensitivity analysis. Notably, the association was also observed in isolated systolic hypertension, isolated diastolic hypertension, and systolic-diastolic hypertension. Subgroup analysis revealed that the inverse association between the PHD score and hypertension risk was more pronounced in nonsmokers and high-sodium intake consumers than in smokers and low-sodium consumers (P-interaction < 0.05). Additionally, mediation analysis revealed that 23.3% of the association between the PHD score and hypertension risk was mediated by the waist-to-height ratio.

CONCLUSION

Our findings suggest that a higher adherence to ELD is associated with a lower risk of hypertension. These results emphasize that ELD may serve as a potential strategy to prevent hypertension.

Effect of prebiotic fiber on physical function and gut microbiota in adults, mostly women, with knee osteoarthritis and obesity: a randomized controlled trial

PURPOSE

Obesity is a primary risk factor for knee osteoarthritis (OA). Prebiotics enhance beneficial gut microbes and can reduce body fat and inflammation. Our objective was to examine if a 6-month prebiotic intervention improved physical function in adults with knee osteoarthritis and obesity. We also measured knee pain, body composition, quality of life, gut microbiota, inflammatory markers, and serum metabolomics.

METHODS

Adults (n = 54, mostly women) with co-morbid obesity (BMI > 30 kg/m2) and unilateral/bilateral knee OA were randomly assigned to prebiotic (oligofructose-enriched inulin; 16 g/day; n = 31) or isocaloric placebo (maltodextrin; n = 21) for 6 months. Performance based-tests, knee pain, quality of life, serum metabolomics and inflammatory markers, and fecal microbiota and short-chain fatty acids were assessed.

RESULTS

Significant between group differences were detected for the change in timed-up-and-go test, 40 m fast paced walk test, and hand grip strength test from baseline that favored prebiotic over placebo. Prebiotic also reduced trunk fat mass (kg) at 6 months and trunk fat (%) at 3 months compared to placebo. There was a trend (p = 0.059) for reduced knee pain at 6 months with prebiotic versus placebo. In gut microbiota analysis, a total of 37 amplicon sequence variants differed between groups. Bifidobacterium abundance was positively correlated with distance walked in the 6-min walk test and hand grip strength. At 6 months, there was a significant separation of serum metabolites between groups with upregulation of phenylalanine and tyrosine metabolism with prebiotic.

CONCLUSION

Prebiotics may hold promise for conservative management of knee osteoarthritis in adults with obesity and larger trials are warranted.

CLINICAL TRIAL REGISTRATION

Clinicaltrials.gov/study/NCT04172688.

Effect of Mutant and Engineered High-Acetate-Producing Saccharomyces cerevisiae var. boulardii Strains in Dextran Sodium Sulphate-Induced Colitis

Acetate-producing Saccharomyces cerevisiae var. boulardii strains could exert improved effects on ulcerative colitis, which here, was preclinically evaluated in an acute dextran sodium sulphate induced model of colitis. Nine-week-old female mice were divided into 12 groups, receiving either drinking water or 2.75% dextran sodium sulphate for 7 days, combined with a daily gavage of various treatments with different levels of acetate accumulation: sham control (phosphate buffered saline, no acetate), non-probiotic control (Baker's yeast, no acetate), probiotic control (Enterol®, transient acetate), and additionally several Saccharomyces cerevisiae var. boulardii strains with respectively no, high, and extra-high acetate accumulation. Disease activity was monitored daily, and feces samples were collected at different timepoints. On day 14, the mice were sacrificed, upon which blood and colonic tissue were collected for analysis. Disease activity in inflamed mice was lower when treated with the high-acetate-producing strain compared to sham and non-probiotic controls. The non-acetate-producing strain showed higher disease activity compared to the acetate-producing strains. Accordingly, higher histologic inflammation was observed in non- or transient-acetate-producing strains compared to the sham control, whereas this increase was not observed for high- and extra-high-acetate-producing strains upon induction of inflammation. These anti-inflammatory findings were confirmed by transcriptomic analysis of differentially expressed genes. Moreover, only the strain with the highest acetate production was superior in maintaining a stable gut microbial alpha-diversity upon inflammation. These findings support new possibilities for acetate-mediated management of inflammation in inflammatory bowel disease by administrating high-acetate-producing Saccharomyces cerevisae var. boulardii strains.

Escherichia coli Nissle 1917 Protects against Sepsis-Induced Intestinal Damage by Regulating the SCFA/GPRs Signaling Pathway

This study explores whether Escherichia coli Nissle 1917 (EcN) can preserve the integrity of the intestinal barrier by modulating the metabolism pathway of short-chain fatty acids (SCFAs) in a C57BL/6J mouse model of lipopolysaccharide (LPS)-induced acute enteritis and a model of a Caco-2 monolayer. The study involved establishing a septic shock model in mice through lipopolysaccharide (LPS) injection. Clinical scores and intestinal permeability were meticulously documented. Immunofluorescence was utilized to localize the tight junction proteins. A quantitative real-time polymerase chain reaction (qRT-PCR) was employed to assess the expression of G protein-coupled receptors (GPRs) signaling. Additionally, the supplement of acetate and butyrate with Caco-2 monolayers to elucidate the potential of EcN in augmenting the intestinal barrier primarily via the modulation of SCFAs and qRT-PCR was performed to detect the expression of tight junction proteins and the activation of the GPRs protein signaling pathway. EcN mitigated the clinical symptoms and reduced intestinal permeability in the colon of LPS-induced mice. It also enhanced the production of SCFAs in the gut and upregulated the expression of SCFA receptor proteins GPR41 and GPR43 in the colon tissue. Our findings reveal that EcN activates the SCFA/GPRs pathway, thereby preserving intestinal barrier function and alleviating inflammation in a mouse sepsis model.

Gut dysbiosis contributes to SCFAs reduction-associated adipose tissue macrophage polarization in gestational diabetes mellitus

AIMS

The prevalence of gestational diabetes mellitus (GDM) has spurred investigations into various interconnected factors, among which gut dysbiosis is notably prominent. Although gut dysbiosis is strongly associated with GDM, the specific role of the gut microbiome in the pathogenesis of GDM remains unknown. This study aims to explore the pathogenesis of GDM from gut microbiota.

MATERIALS AND METHODS

In our study, we constructed two GDM mice models: one induced by a high-fat diet (HFD) and the other through fecal microbiota transplantation (FMT) from GDM patients. In vitro, we used a co-culture system of RAW264.7 and 3T3-L1 adipocytes.

KEY FINDINGS

We induced a GDM-like state in pregnant mice by FMT from GDM patients, which was consistent with the HFD model. A potential mechanism identified involves the diminished abundance of SCFA-producing microbiota, which reduces SCFAs, particularly propionic acid and butyric acid. In vitro, butyric and propionic acids were observed to alleviate LPS-induced TLR4-NF-κB activation, thereby reducing inflammation levels and inhibiting adipose insulin resistance via the PI3K/AKT signaling pathway. This reduction appears to trigger the polarization of adipose tissue macrophages toward M1 and promote insulin resistance in adipose tissue.

SIGNIFICANCE

Our study fills this knowledge gap by finding that alterations in gut microbiota have an independent impact on hyperglycemia and insulin resistance in the GDM state. In vivo and in vitro, gut dysbiosis is linked to adipose tissue inflammation and insulin resistance via the bacterial product SCFAs in the GDM state, providing new insights into the pathogenesis of GDM.

Glaucoma and the Human Microbiome

PURPOSE OF REVIEW

To explore a view of the human microbiome as an interconnected, functional, dynamic system that may be linked to the pathogenesis and progression of glaucoma.

METHODS

A literature review was undertaken that included publications from 1966 to 2023.

RESULTS

Bacterial lipopolysaccharides (LPS) activate toll-like receptors (TLR) and mediate the human immune response. The LPS-TLR4 pathway is a potential avenue for the ocular, gut, and oral microbiomes to interface and/or influence ocular disease. Studies of gut dysbiosis have shown that alterations in the healthy microbiota can predispose the host to immune-mediated inflammatory and neurodegenerative conditions, while oral and ocular surface dysbiosis has been correlated with glaucoma. While developmental exposure to commensal microflora has shown to be necessary for the autoimmune and neurodegenerative responses to elevated intraocular pressure to take place, commensal bacterial products like short-chain fatty acids have regulatory effects protective against glaucoma.

SUMMARY

Alterations to human microbiotas have been associated with changes in intestinal permeability, gene regulation, immune cell differentiation, and neural functioning, which may predispose the host to glaucoma. Select microbes have been highlighted for their potential contributions to glaucoma disease progression or protection, raising the potential for microbiota-based treatment modalities. Current topical glaucoma treatments may disrupt the ocular surface microbiota, potentially having ramifications on host health. Further study of the relationships between human microbiome and glaucoma is needed.

The gut-immune axis during hypertension and cardiovascular diseases

The gut-immune axis is a relatively novel phenomenon that provides mechanistic links between the gut microbiome and the immune system. A growing body of evidence supports it is key in how the gut microbiome contributes to several diseases, including hypertension and cardiovascular diseases (CVDs). Evidence over the past decade supports a causal link of the gut microbiome in hypertension and its complications, including myocardial infarction, atherosclerosis, heart failure, and stroke. Perturbations in gut homeostasis such as dysbiosis (i.e., alterations in gut microbial composition) may trigger immune responses that lead to chronic low-grade inflammation and, ultimately, the development and progression of these conditions. This is unsurprising, as the gut harbors one of the largest numbers of immune cells in the body, yet is a phenomenon not entirely understood in the context of cardiometabolic disorders. In this review, we discuss the role of the gut microbiome, the immune system, and inflammation in the context of hypertension and CVD, and consolidate current evidence of this complex interplay, whilst highlighting gaps in the literature. We focus on diet as one of the major modulators of the gut microbiota, and explain key microbial-derived metabolites (e.g., short-chain fatty acids, trimethylamine N-oxide) as potential mediators of the communication between the gut and peripheral organs such as the heart, arteries, kidneys, and the brain via the immune system. Finally, we explore the dual role of both the gut microbiome and the immune system, and how they work together to not only contribute, but also mitigate hypertension and CVD.

Feeding gut microbes to nourish the brain: unravelling the diet-microbiota-gut-brain axis

The prevalence of brain disorders, including stress-related neuropsychiatric disorders and conditions with cognitive dysfunction, is rising. Poor dietary habits contribute substantially to this accelerating trend. Conversely, healthy dietary intake supports mood and cognitive performance. Recently, the communication between the microorganisms within the gastrointestinal tract and the brain along the gut-brain axis has gained prominence as a potential tractable target to modulate brain health. The composition and function of the gut microbiota is robustly influenced by dietary factors to alter gut-brain signalling. To reflect this interconnection between diet, gut microbiota and brain functioning, we propose that a diet-microbiota-gut-brain axis exists that underpins health and well-being. In this Review, we provide a comprehensive overview of the interplay between diet and gut microbiota composition and function and the implications for cognition and emotional functioning. Important diet-induced effects on the gut microbiota for the development, prevention and maintenance of neuropsychiatric disorders are described. The diet-microbiota-gut-brain axis represents an uncharted frontier for brain health diagnostics and therapeutics across the lifespan.

Design strategies, advances and future perspectives of colon-targeted delivery systems for the treatment of inflammatory bowel disease

Inflammatory bowel diseases (IBD) significantly contribute to high mortality globally and negatively affect patients' qualifications of life. The gastrointestinal tract has unique anatomical characteristics and physiological environment limitations. Moreover, certain natural or synthetic anti-inflammatory drugs are associated with poor targeting, low drug accumulation at the lesion site, and other side effects, hindering them from exerting their therapeutic effects. Colon-targeted drug delivery systems represent attractive alternatives as novel carriers for IBD treatment. This review mainly discusses the treatment status of IBD, obstacles to drug delivery, design strategies of colon-targeted delivery systems, and perspectives on the existing complementary therapies. Moreover, based on recent reports, we summarized the therapeutic mechanism of colon-targeted drug delivery. Finally, we addressed the challenges and future directions to facilitate the exploitation of advanced nanomedicine for IBD therapy.

Short-chain fatty acids ameliorate imiquimod-induced skin thickening and IL-17 levels and alter gut microbiota in mice: a metagenomic association analysis

Short-chain fatty acids (SCFAs) have been proposed to have anti-inflammatory effects and improve immune homeostasis. We aimed to examine the effects of SCFAs on skin phenotype, systemic inflammation, and gut microbiota in mice with psoriasis-like inflammation. Imiquimod (IMQ)-treated C57BL/6 mice served as the study model. We conducted a metagenomic association study of IMQ-mice treated with SCFAs or anti-IL-17 antibody using whole-genome shotgun sequencing. The associations among SCFA supplements, skin thickness, circulating inflammatory profiles, and fecal microbiota profiles were investigated. The microbiome study was performed using pipelines for phylogenetic analysis, functional gene analysis, and pathway analysis. In IMQ-treated mice, there were increases in skin thickness and splenic weight, as well as unique fecal microbial profiles. SCFAs ameliorated IMQ-induced skin thickening, splenic weight gain, and serum IL-17F levels, with results that were comparable with those receiving anti-IL-17 treatment. IMQ-treated mice receiving SCFAs had greater microbial diversity than mice treated with IMQ alone. SCFAs and anti-IL17 treatment were associated with alteration of gut microbiota, with increased prevalences of Oscillospiraceae and Lachnopiraceae and decreased prevalences of Muribaculaceae and Bacteroides, which have been predicted to be associated with increased glycan degradation, phenylalanine metabolism, and xylene degradation. SCFAs may mitigate IMQ-induced skin thickening and IL-17F levels and alter fecal microbiota profiles in IMQ-treated mice.

Interactions between Dietary Antioxidants, Dietary Fiber and the Gut Microbiome: Their Putative Role in Inflammation and Cancer

The intricate relationship between the gastrointestinal (GI) microbiome and the progression of chronic non-communicable diseases underscores the significance of developing strategies to modulate the GI microbiota for promoting human health. The administration of probiotics and prebiotics represents a good strategy that enhances the population of beneficial bacteria in the intestinal lumen post-consumption, which has a positive impact on human health. In addition, dietary fibers serve as a significant energy source for bacteria inhabiting the cecum and colon. Research articles and reviews sourced from various global databases were systematically analyzed using specific phrases and keywords to investigate these relationships. There is a clear association between dietary fiber intake and improved colon function, gut motility, and reduced colorectal cancer (CRC) risk. Moreover, the state of health is reflected in the reciprocal and bidirectional relationships among food, dietary antioxidants, inflammation, and body composition. They are known for their antioxidant properties and their ability to inhibit angiogenesis, metastasis, and cell proliferation. Additionally, they promote cell survival, modulate immune and inflammatory responses, and inactivate pro-carcinogens. These actions collectively contribute to their role in cancer prevention. In different investigations, antioxidant supplements containing vitamins have been shown to lower the risk of specific cancer types. In contrast, some evidence suggests that taking antioxidant supplements can increase the risk of developing cancer. Ultimately, collaborative efforts among immunologists, clinicians, nutritionists, and dietitians are imperative for designing well-structured nutritional trials to corroborate the clinical efficacy of dietary therapy in managing inflammation and preventing carcinogenesis. This review seeks to explore the interrelationships among dietary antioxidants, dietary fiber, and the gut microbiome, with a particular focus on their potential implications in inflammation and cancer.

Dress me an outfit: advanced probiotics hybrid systems for intelligent IBD therapy

Inflammation bowel disease (IBD) has emerged as a public health challenge worldwide; with high incidence and rapid prevalence, it has troubled billions of people and further induced multitudinous systemic complications. Recent decade has witnessed the vigorous application of food-borne probiotics for IBD therapy; however, the complicated and changeable environments of digestive tract have forced probiotics to face multiple in vivo pressures, consequently causing unsatisfied prophylactic or therapeutic efficacy attributed to off-targeted arrival, damaged viability, insufficient colonization efficiency, etc. Fortunately, arisen hybrid technology has provided versatile breakthroughs for the targeted transplantation of probiotics. By ingeniously modifying probiotics to form probiotics hybrid systems (PHS), the biological behaviors of probiotics in vivo could be mediated, the interactions between probiotics with intestinal components can be facilitated, and diverse advanced probiotic-based therapies for IBD challenge can be developed, which attribute to the intelligent response to microenvironment of PHS, and intelligent design of PHS for multiple functions combination. In this review, various PHS were categorized and their intestinal behaviors were elucidated systematically, their therapeutic effects and intrinsic mechanism were further analyzed. Besides, shortages of present PHS and the corresponding solutions have been discussed, based on which the future perspectives of this field have also been proposed. The undeniable fact is that PHS show an incomparable future to bring the next generation of advanced food science.

In vitro digestion and fermentation characteristics of eight kinds of pulses and suggestions for different populations

Pulse-based diets are attracting attention for their potential in combating diet-related non-communicable diseases. However, limited research studies have focused on the digestive and fermentative properties of pulses, which are crucial for exerting benefits. Here, we investigated the in vitro digestibility of starch/protein, along with the fermentation characteristics, of eight pulses and their pastes, including white kidney beans, adzuki beans, cowpeas, broad beans, mung beans, chickpeas, white lentils, and yellow peas. The findings indicated that pulse flours and pastes were low GL food (estimated GL < 10) and had a low degree of protein hydrolysis during simulated gastrointestinal digestion. During in vitro fermentation, pulses flours and pastes decreased the fermentation pH, increased the level of short-chain fatty acids (mainly consisting of valeric acid, followed by acetic acid, propionic acid, butyric acid, isobutyric acid, and isovaleric acid), and positively modulated the microbiota composition over time, specifically reducing the ratio of Firmicutes to Bacteroidetes. In addition, we found that boiling could affect the in vitro digestion and fermentation characteristics of pulses, possibly depending on their intrinsic nutrient characteristics. This research could provide a comprehensive summary of the nutrient content, digestibility, and fermentation of eight pulses and their pastes. Guided by factor analysis, for different individuals' consumption, pulses, cowpeas, broad beans, white lentils, and white kidney beans were preferred for diabetic individuals, yellow peas and white lentils were preferred for intestinal homeostasis disorders, and white lentils, broad beans, white kidney beans, and cowpeas were suitable for obese individuals, in which white lentils were considered healthier and suggested for healthy adults.

Recommendations for the Use of Dietary Fiber to Improve Blood Pressure Control

According to several international, regional, and national guidelines on hypertension, lifestyle interventions are the first-line treatment to lower blood pressure (BP). Although diet is one of the major lifestyle modifications described in hypertension guidelines, dietary fiber is not specified. Suboptimal intake of foods high in fiber, such as in Westernized diets, is a major contributing factor to mortality and morbidity of noncommunicable diseases due to higher BP and cardiovascular disease. In this review, we address this deficiency by examining and advocating for the incorporation of dietary fiber as a key lifestyle modification to manage elevated BP. We explain what dietary fiber is, review the existing literature that supports its use to lower BP and prevent cardiovascular disease, describe the mechanisms involved, propose evidence-based target levels of fiber intake, provide examples of how patients can achieve the recommended targets, and discuss outstanding questions in the field. According to the evidence reviewed here, the minimum daily dietary fiber for adults with hypertension should be >28 g/day for women and >38 g/day for men, with each extra 5 g/day estimated to reduce systolic BP by 2.8 mm Hg and diastolic BP by 2.1 mm Hg. This would support a healthy gut microbiota and the production of gut microbiota-derived metabolites called short-chain fatty acids that lower BP. Awareness about dietary fiber targets and how to achieve them will guide medical teams on better educating patients and empowering them to increase their fiber intake and, as a result, lower their BP and cardiovascular disease risk.

Systematic review of the association between short-chain fatty acids and allergic diseases

We performed a systematic review to investigate the current evidence on the association between allergic diseases and short chain fatty acids (SCFAs), which are microbially produced and suggested as one mechanism on how gut microbiome affects the risk of allergic diseases. Medline, Embase and Web of Science were searched from data inception until September 2022. We identified 37 papers, of which 17 investigated prenatal or early childhood SCFAs and the development of allergic diseases in childhood, and 20 assessed SCFAs in patients with pre-existing allergic diseases. Study design, study populations, outcome definition, analysis method and reporting of the results varied between papers. Overall, there was some evidence showing that the three main SCFAs (acetate, propionate and butyrate) in the first few years of life had a protective effect against allergic diseases, especially for atopic dermatitis, wheeze or asthma and IgE-mediated food allergy in childhood. The association between each SCFA and allergic disease appeared to be different by disease and the age of assessment. Further research that can determine the potentially timing specific effect of each SCFA will be useful to investigate how SCFAs can be used in treatment or in prevention against allergic diseases.

Short-chain fatty acid levels in stools of patients with inflammatory bowel disease are lower than those in healthy subjects

OBJECTIVE

Short-chain fatty acids (SCFAs) are produced when the microbiota in the large intestine cause fermentation of dietary carbohydrates and fibers. These fatty acids constitute the primary energy source of colon mucosa cells and have a protective effect in patients suffering from inflammatory bowel disease (IBD). This study aimed to compare the SCFA levels in the stools of patients with IBD and healthy controls.

METHOD

Healthy controls and patients with IBD aged 18 and over were included in the study. Stool samples from all patients and healthy controls were collected, and stool acetic acid, propionic acid, and butyric acid levels were measured using a gas chromatography-mass spectrometry measurement method.

RESULTS

In this study, 64 participants were divided into two groups: 34 were in IBD (Crohn disease and ulcerative colitis) and 30 were in healthy control group. When fecal SCFA concentrations of IBD and healthy control groups were compared, a statistically significant difference was observed between them. When the fecal SCFA concentrations of Crohn's disease and ulcerative colitis patients in the IBD group were compared, however, no statistically significant difference was observed between them. Furthermore, when the participants' diet type (carbohydrate-based, vegetable-protein-based and mixed diet) and the number of meals were compared with fecal SCFA concentrations, no statistically significant difference was observed between them.

CONCLUSION

In general, fecal SCFA levels in patients with IBD were lower than those in healthy controls. Moreover, diet type and the number of meals had no effect on stool SCFA levels in patients with IBD and healthy individuals.