Short-chain fatty acids and human colonic function: roles of resistant starch and nonstarch polysaccharides

Evolution of multi-scale structure and microbiota metabolism of lentil resistant starch during the dynamic fermentation in vitro

This study investigated the structural changes of resistant starch (RS) derived from autoclaved lentil starch (ALRS) and untreated lentil starch (ULRS) during in vitro colonic fermentation, as well as their regulatory effects on the composition of the intestinal microbiota. Following in vitro fermentation, both RS samples exhibited a progressive decrease in molecular weight and a gradual increase in double helix/order. Bifidobacterium was more abundant in ULRS during the initial period of fermentation, while ALRS showed higher abundance in the later stage. ALRS demonstrated greater production of short-chain fatty acids (SCFAs) compared to ULRS, likely attributed to its higher structural order and faster fermentation pattern. The distinct surface morphologies of ULRS and ALRS played a crucial role in determining the accessibility of RS substrates for microbial fermentation. These different structural patterns also influenced the shifts in microbial composition in fecal cultures, leading to variations in SCFAs production through anaerobic fermentation.

In vivo absorption, in vitro simulated digestion, and fecal fermentation properties of Imperata cylindrica polysaccharides and their effects on gut microbiota

Recently we have investigated polysaccharide from Imperata cylindrica (ICP) for its physicochemical structure and biological activities. However, the digestion characteristics have yet to be understood. This study investigated the digestion and metabolism characteristics of ICP through in vivo fluorescence tracking, in vitro simulated digestion, fecal fermentation experiments, and microbial sequencing. The results showed that ICP significant distribution in the gastrointestinal tract and kidneys. ICP underwent slight degradation during simulated gastric and intestinal digestion. During fecal fermentation, the utilization degree of ICP and the concentration of short-chain fatty acids (SCFAs) increased. ICP promoted the increase of beneficial microbial abundance. To understand the impact of ICP on the integrity and health of intestinal tissues, molecular docking was employed to preliminarily predict the interaction between ICP and key proteins. The results revealed that ICP could recognize and bind to key proteins through high-affinity targeting binding sites.

Utilization of diverse probiotics to create human health promoting fatty acids: A review

Many probiotics produce functional lipids with health-promoting properties, such as short-chain fatty acids, linoleic acid and omega-3 fatty acids. They have been shown to maintain gut health, strengthen the intestinal barrier, and have anti-inflammatory and antioxidant effects. In this article, we provide an up-to-date review of the various functional lipids produced by probiotics. These probiotics can be incorporated into foods, supplements, or pharmaceuticals to produce these functional lipids in the human colon, or they can be used in industrial biotechnology processes to generate functional lipids, which are then isolated and used as ingredients. We then highlight the different physiological functions for which they may be beneficial to human health, in addition to discussing some of the challenges of incorporating probiotics into commercial products and some potential solutions to address these challenges. Finally, we highlight the importance of testing the efficacy and safety of the new generation of probiotic-enhanced products, as well as the great potential for the marketization of related products.

Advancements in modifying insoluble dietary fiber: Exploring the microstructure, physicochemical properties, biological activity, and applications in food industry-A review

Recent research has primarily focused on strategies for modifying insoluble dietary fiber (IDF) to enhance its performance and functionality. IDF is obtained from various inexpensive sources and can be manipulated to alter its biological effects, making it possible to revolutionize food processing and nutrition. In this review, multiple IDF modification techniques are thoroughly examined and discussed, with particular emphasis on the resulting changes in the physicochemical properties, biological activities, and microstructure of the fiber. An extensive overview of the practical applications of modified IDF in food processing is provided. Our study aims to raise awareness about the vast possibilities presented by modified IDF and encourage further exploration and utilization of this field in the realm of food production.

Impact of different organic acids on heat-moisture treated potato starch for enhancing prebiotic potential

This research verified the in vitro digestive properties of potato starch modified with citric acid (CA), malic acid (MA), and tartaric acid (TA), and evaluated its prebiotic potential. The resistant starch (RS) content in CA- or MA-modified starch was greater than that in native starch. Furthermore, after cooking, all modified starches exhibited an increase in RS content by 2.3 to 3.3 times compared to native starch, which has a 29.81% RS content, demonstrating high thermal stability. Probiotic bacteria demonstrated increased viability, raiging form 6.38-6.85 log CFU/mL, when cultured with modified starch, in contrast to 4.48 log CFU/mL with glucose. During animal testing, modified starches consistently improved gastrointestinal transit, fecal moisture, and lipid levels. Notably, CA-, MA- or TA-modified starches promoted beneficial bacteria growth by providing short-chain fatty acids, with CA-modified starch proving to be the most potent.

Polysaccharides in Medicinal and Food Homologous Plants regulate intestinal flora to improve type 2 diabetes: Systematic review

BACKGROUND

Medicinal and food homologous plants (MFHPs) which can improve Type 2 Diabetes Mellitus (T2DM) draw significant attention among the public due to their low toxicity and more safety. Polysaccharides, one of the various active components of MFHPs, are recognized as effective modulators of the intestinal flora. By altering the composition of intestinal flora and affecting their metabolic products, polysaccharides can improve T2DM, making them a central focus of anti-diabetic research.

PURPOSE

The purpose of this study is to systematically review the mechanism by which polysaccharides from MFHPs (MFHPPs) regulate the composition of intestinal flora and its metabolic products to improve T2DM.

METHODS

This study follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and conducts a comprehensive search on the PubMed, Web of Science and Embase databases. All experimental articles published up to March 4, 2024, are included in the search.

RESULTS

Among the 5733 articles reviewed, 29 were selected, covering 22 different MFHPs. MFHPPs can improve T2DM, particularly in lowering blood glucose levels, with consistent results. MFHPPs can regulate the diversity of intestinal flora in T2DM animal models, primarily affecting four phyla: decreasing Firmicutes and Proteobacteria while increasing Bacteroidetes and Actinobacteriota. At the genus level, the improvement of T2DM by MFHPPs is associated with the modulation of 12 key genera: Allobaculum, Akkermansia, Bifidobacterium, Lactobacillus, Helicobacter, Halomonas, Olsenella, Oscillospira, Shigella, Escherichia-Shigella, Romboutsia and Bacteroides. At the molecular level, MFHPPs primarily act by modulating the intestinal flora to increase short-chain fatty acid levels, promote the secretion of glucagon-like peptide-1, influence the IGF1/PI3K/AKT signaling pathway, or the PI3K/AKT/GSK-3β pathway, to lower blood glucose levels. They may also improve T2DM by working in glucose metabolism through the "microbiota-gut-organ" axis. MFHPPs can also alleviate T2DM by mitigating inflammation and oxidative stress: MFHPPs regulate intestinal flora to reduce lipopolysaccharide "leakage" and enhance intestinal mucosal permeability to tackle the inflammation associated with T2DM; MFHPPs enhance the expression of oxidative stress-related enzymes to alleviate oxidative stress and improve T2DM. Lastly, from a metabolic pathway perspective, MFHPPs are primarily involved in the metabolism of amino acids and their derivatives, carbohydrate metabolism and glutathione metabolism.

CONCLUSION

MFHPPs can improve T2DM by enhancing the composition of intestinal flora, regulating its metabolic products to promote insulin secretion, inhibiting glucagon-like peptide secretion, facilitating glycogen synthesis, reducing inflammation levels and alleviating oxidative stress. Furthermore, MFHPPs demonstrate potential protective effects on critical organs such as the pancreas, liver, kidneys and heart. Therefore, MFHPPs demonstrate significant clinical potential. However, most studies can only indicate the potential of MFHPPs intervention in improving T2DM through the intestinal flora. The causality between MFHPPs regulating the intestinal flora and T2DM requires further investigation.

Physiologic hypoxia in the intestinal mucosa: a central role for short-chain fatty acids

The intestinal mucosa is a dynamic surface that facilitates interactions between the host and an outside world that includes trillions of microbes, collectively termed the microbiota. This fine balance is regulated by an energetically demanding physical and biochemical barrier that is formed by the intestinal epithelial cells. In addition, this homeostasis exists at an interface between the anaerobic colonic lumen and a highly oxygenated, vascularized lamina propria. The resultant oxygen gradient within the intestine establishes "physiologic hypoxia" as a central metabolic feature of the mucosa. Although oxygen is vital for energy production to meet cellular metabolism needs, the availability of oxygen has far-reaching influences beyond just energy provision. Recent studies have shown that the intestinal mucosa has purposefully adapted to use differential oxygen levels largely through the presence of short-chain fatty acids (SCFAs), particularly butyrate (BA). Intestinal epithelial cells use butyrate for a multitude of functions that promote mucosal homeostasis. In this review, we explore how the physiologic hypoxia profile interfaces with SCFAs to benefit host mucosal tissues.

The effect of sodium butyrate administered in ovo on the health status and intestinal response in broiler chicken

A healthy gut is one of the main factors influencing bird response. Over the years, efforts have been made to improve intestinal health. One of the supporting methods may be enriching the diet with bioactive ingredients, including sodium butyrate (SB). One of the possible ways of administering such supplementation is in ovo technology. Over the years, research has shown that administering bioactive substances this way has a positive effect on the health status of chickens. The current study aimed to modify the gut microbiota of broiler chickens by in ovo stimulation on d 12 of egg incubation with SB and to determine the changes occurring in intestines. One thousand eggs were incubated and injected with 0.1, 0.3, or 0.5% SB on d 12 of incubation. The control group was injected with physiological saline. Samples collected for analysis were obtained postmortem from 42-day-old ROSS 308 broiler chickens. Growth performance parameters were also monitored during broiler rearing. Gene expression analysis showed significant changes in the levels of IL4, IFNγ, AvBD1, TJAP and MUC6 genes in the ileum. However, the IL8, MUC2 and MUC6 genes were significantly expressed in the cecal mucosa. These changes depended on the administered dose of butyrate. There was no effect of in ovo administration of various doses of SB on digesta pH, SCFA level and histological parameters. However, a significant increase in Bifidobacterium bacteria was detected in the ileum after administration of a dose of 0.5% SB and in the cecum after administration of a dose of 0.3%. Administration of SB in ovo has the potential to support intestinal health in poultry. The effects depend on the administered dose, while the results indicate a dose of 0.3% as the most optimal.

Does the gut microbiome influence disc health and disease? The interplay between dysbiosis, pathobionts, and disc inflammation: a pilot study

BACKGROUND CONTEXT

Gut microbiome alterations resulting in inflammatory responses have been implicated in many distant effects on different organs. However, its influence on disc health is still not fully investigated.

PURPOSE

Our objective was to document the gut biome in healthy volunteers and patients with disc degeneration and to understand the role of gut dysbiosis on human disc health.

STUDY DESIGN

Experimental case-control study.

PATIENT SAMPLE

We included 40 patients with disc degeneration (DG) and 20 healthy volunteers (HV). HV comprised of age groups 30 to 60 years with no known record of back pain and no clinical comorbidities, with normal MRI. Diseased group (DG) were patients in the same age group undergoing surgery for disc disease (disc herniation-25; discogenic stenosis-15) and without instability (with Modic-20; and non-Modic-20).

OUTCOME MEASURES

N/A.

METHODS

We analyzed 16S V3-V4 rDNA gut metagenome from 20 healthy volunteers (HV) and compared the top signature genera from 40 patients with disc degeneration (DG) across Modic and non-Modic groups. Norgen Stool DNA Kit was used for DNA extraction from ∼200 mg of each faecal sample collected using the Norgen Stool Collection Kit.16S V3-V4 rDNA amplicons were generated with universal bacterial primers 341F and 806R and amplified with Q5 High-Fidelity DNA Polymerase. Libraries were sequenced with 250×2 PE to an average of 0.1 million raw reads per sample (Illumina Novaseq 6000). Demultiplexed raw data was assessed with FastQC, and adapter trimmed reads >Q30 reads were processed in the QIME2 pipeline. Serum C-reactive protein (CRP) was measured by the immunoturbimetry method and Fatty acid-binding protein 5 (FABP5) was measured in albumin-globulin-depleted plasma through global proteome analysis.

RESULTS

We observed significant gut dysbiosis between HV and DG and also between the Modic and non-Modic groups. In the Modic group, commensals Bifidobacterium and Ruminococcus were significantly depleted, while pathobionts Streptococcus, Prevotella, and Butryvibrio were enriched. Firmicutes/Bacteroidetes ratio was decreased in DG (Modic-0.62, non-Modic-0.43) compared to HV (0.70). Bacteria-producing beneficial short-chain fatty acids were also depleted in DG. Elevated serum CRP and increased FABP5 were observed in DG.

CONCLUSION

The study revealed gut dysbiosis, an altered Firmicutes/Bacteroidetes ratio, reduced SCFA-producing bacteria, and increased systemic and local inflammation in association with disc disease, especially in Modic changes. The findings have considerable importance for our understanding and prevention of disc degeneration.

Stratification of human gut microbiomes by succinotype is associated with inflammatory bowel disease status

BACKGROUND

The human gut microbiome produces and consumes a variety of compounds that interact with the host and impact health. Succinate is of particular interest as it intersects with both host and microbiome metabolism. However, which gut bacteria are most responsible for the consumption of intestinal succinate is poorly understood.

RESULTS

We build upon an enrichment-based whole fecal sample culturing approach and identify two main bacterial taxa that are responsible for succinate consumption in the human intestinal microbiome, Phascolarctobacterium and Dialister. These two taxa have the hallmark of a functional guild and are strongly mutual exclusive across 21,459 fecal samples in 94 cohorts and can thus be used to assign a robust "succinotype" to an individual. We show that they differ with respect to their rate of succinate consumption in vitro and that this is associated with higher concentrations of fecal succinate. Finally, individuals suffering from inflammatory bowel disease (IBD) are more likely to have the Dialister succinotype compared to healthy subjects.

CONCLUSIONS

We identified that only two bacterial genera are the key succinate consumers in human gut microbiome, despite the fact that many more intestinal bacteria encode for the succinate pathway. This highlights the importance of phenotypic assays in functionally profiling intestinal microbiota. A stratification based on "succinotype" is to our knowledge the first function-based classification of human intestinal microbiota. The association of succinotype with IBD thus builds a bridge between microbiome function and IBD pathophysiology related to succinate homeostasis. Video Abstract.

Association between empirically derived nutrient patterns and breast cancer: a case-control study in a Middle Eastern country

PURPOSE

The risk of breast cancer (BC) and related mortality have increased in Middle-East countries during recent decades. The relationship between several nutrient intakes and the risk of BC has been investigated in several studies. However, few studies have estimated the effects of patterns of different nutrient intake on the risk of BC in this region.

METHODS

A total of 453 patients who were recently diagnosed with breast cancer and 516 healthy women participated in the current case-control study. To evaluate the dietary intakes, we used a validated 168-item food frequency questionnaire (FFQ) during the last year. Nutrient Patterns (NPs) were extracted through factor analysis (FA) of energy-adjusted twenty-six nutrients. The relationship between nutrient patterns and the risk of breast cancer in pre and post-menopausal women was estimated by multivariable regression.

RESULTS

Four major nutrient patterns were identified in the current study. The first nutrient pattern was rich in animal protein, retinol, riboflavin, pantothenic acid, cobalamin, and calcium. Higher saturated fatty acids (SFAs), mono-unsaturated fatty acids (MUFAs), polyunsaturated fatty acids (PUFAs), and trans fatty acids (TFAs), and lower intakes of niacin were observed in nutrient pattern 2. The third nutrient pattern was rich in fiber, potassium, and vitamin C. Nutrient pattern 4, was associated with higher intakes of vegetable protein, alpha-tocopherol, and magnesium. A significant inverse relationship was observed between adherence to nutrient pattern 3 and the risk of BC in all participants [odds ratio (OR) = 0.70, 95% confidence interval (CI): 0.50, 0.97, P = 0.03) and pre-menopausal women (OR = 0.59 (0.39-0.89), P = 0.01).

CONCLUSION

Decreasing odds of breast cancer were observed by adherence to a nutrient pattern high in dietary fiber, vitamin C, and potassium. Future prospective investigations are recommended to confirm these findings.

Variation and Abundance of Resistant Starch in Selected Banana Cultivars in Uganda

The physiochemical, structural, and molecular characteristics of starch influence its functional properties, thereby dictating its utilization. The study aimed to profile the properties and quantity of resistant starch (RS) from 15 different banana varieties, extracted using a combination of alkaline and enzyme treatments. Granular structure and molecular organization were analyzed using light microscopy, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The physiochemical and functional properties were also investigated. RS content ranged from 49% to 80% without significant relationship to amylose (AM) (r = -0.1062). SEM revealed significant microarchitectural differences on the granules potentially affecting granule digestibility. FTIR and chemometrics identified differences in the crystalline peaks, yielding varying degrees of the molecular order of the RS polymers that aid in differentiating the RS sources. Despite similar solubility and swelling profiles, the pasting profiles varied across varieties, indicating high paste stability in hydrothermal processing. Clarity ranged from 43% to 93%, attributed to amylose leaching. This study highlights that RS from bananas varies in quantity, structure, and functionality, necessitating individualized approaches for processing and utilization.

The gut microbiota in thrombosis

The gut microbiota has emerged as an environmental risk factor that affects thrombotic phenotypes in several cardiovascular diseases. Evidence includes the identification of marker species by sequencing studies of the gut microbiomes of patients with thrombotic disease, the influence of antithrombotic therapies on gut microbial diversity, and preclinical studies in mouse models of thrombosis that have demonstrated the functional effects of the gut microbiota on vascular inflammatory phenotypes and thrombus formation. In addition to impaired gut barrier function promoting low-grade inflammation, gut microbiota-derived metabolites have been shown to act on vascular cell types and promote thrombus formation. Therefore, these meta-organismal pathways that link the metabolic capacities of gut microorganisms with host immune functions have emerged as potential diagnostic markers and novel drug targets. In this Review, we discuss the link between the gut microbiota, its metabolites and thromboembolic diseases.

Causal effects of gut microbiota, metabolites, immune cells, liposomes, and inflammatory proteins on anorexia nervosa: A mediation joint multi-omics Mendelian randomization analysis

BACKGROUND

Anorexia nervosa (AN) is a significant psychological disorder influenced by environmental and genetic elements. Emerging research highlights the pivotal role of the gut microbiome in the development of diverse mental health conditions. This study aims to explore the causal effects and interactions of the gut microbiome, metabolites, immune cells, lipids, and inflammatory proteins on the risk of anorexia nervosa through mediation and multi-omics Mendelian Randomization (MR) analysis.

METHODS

This study used data from the FinnGen genome-wide association study (GWAS) of AN (N = 402,625), integrated with GWAS data on 473 of gut microbiota (N = 5959), 233 metabolites (N = 136,016), 731 immune cells (N = 3757), 179 lipids (N = 7174), and 91 inflammatory proteins (N = 14,824). This study used the univariate MR (UVMR), mediation MR analysis, and sensitivity analysis to assess the potential causal associations between these biomarkers and AN.

RESULTS

The inverse variance weighted (IVW) results suggest that 25 gut microbiota have causal effects on AN. Firmicutes E (OR: 0.294, 95 % CI: 0.107-0.806, P = 0.017), RUG147 (OR: 0.386, 95 % CI: 0.151-0.990, P = 0.048), CAG-977 (OR: 0.562, 95 % CI: 0.378-0.837, P = 0.005), Desulfobacterota A (OR: 0.651, 95 % CI: 0.466-0.909, P = 0.012), CAG-269 sp002372935 (OR: 0.673, 95 % CI: 0.483-0.937, P = 0.019), Klebsiella (OR: 0.684, 95 % CI: 0.566-0.827, P = 0.00009), Desulfovibrionia (OR: 0.706, 95 % CI: 0.538-0.926, P = 0.012), Klebsiella pneumoniae (OR: 0.737, 95 % CI: 0.600-0.906, P = 0.004), Desulfovibrionales (OR: 0.786, 95 % CI: 0.631-0.979, P = 0.031), CAG-776 (OR: 0.787, 95 % CI: 0.632-0.980, P = 0.032), Desulfovibrionaceae (OR: 0.788, 95 % CI: 0.635-0.978, P = 0.030). 13 gut microbiota were risk factors for AN, including Parachlamydiales (OR: 3.134，95%CI: 1.185-8.287, P = 0.021), Paenibacillus J (OR: 2.366，95%CI: 1.305-4.29, P = 0.005), Gillisia (OR: 1.947，95%CI: 1.135-3.339, P = 0.016), UBA1191 (OR: 1.856，95%CI: 1.221-2.822, P = 0.004), UBA7703 (OR: 1.843，95%CI: 1.032-3.289, P = 0.039), Faecalicatena sp002161355 (OR: 1.788，95%CI: 1.114-2.870, P = 0.016), Johnsonella ignava (OR: 1.742，95%CI: 1.031-2.944, P = 0.038), Staphylococcus aureus (OR: 1.614, 95%CI: 1.007-2.588, P = 0.047), Comamonas (OR: 1.522，95%CI: 1.004-2.307, P = 0.048), Ruminococcus D (OR: 1.24，95%CI: 1.050-1.464, P = 0.011), CAG-349 (OR: 1.198，95%CI: 1.048-1.370, P = 0.008), Ruminococcus D bicirculans (OR: 1.175，95%CI: 1.001-1.379, P = 0.048), CAG-177 (OR: 1.272，95%CI: 1.077-1.503, P = 0.005). Reverse MR analysis showed that causal effect of AN on 18 gut microbiota, but to a lesser extent. 12 metabolites have causal effects on AN. There are 7 protective factors, including glucose levels (OR: 0.700, 95%CI: 0.550-0.893, P = 0.004), isoleucine levels (OR: 0.769, 95%CI: 0.602-0.983, P = 0.036), phospholipids in large VLDL (OR: 0.856, 95%CI: 0.736-0.996, P = 0.044), total lipids in large VLDL (OR: 0.860, 95%CI: 0.740-0.999, P = 0.049), total lipids in small VLDL (OR: 0.863, 95%CI: 0.751-0.992, P = 0.038), free cholesterol in small VLDL (OR: 0.86, 95%CI: 0.752-0.996, P = 0.044), and free cholesterol in medium VLDL (OR: 0.866, 95%CI: 0.752-0.998, P = 0.047). There are 5 risk factors, including estimated degree of unsaturation (OR: 1.174, 95%CI: 1.009-1.367, P = 0.039), free cholesterol to total lipids ratio in small VLDL (OR: 1.199, 95%CI: 1.017-1.414, P = 0.031), phospholipids to total lipids ratio in small VLDL (OR: 1.216, 95%CI: 1.008-1.467, P = 0.041), total cholesterol levels in small HDL (OR: 1.241, 95%CI: 1.008-1.530, P = 0.042), and phospholipids to total lipids ratio in medium VLDL (OR: 1.280, 95%CI: 1.055-1.553, P = 0.012). Reverse MR analysis showed that AN had a causal effect on 15 metabolites. Mediation analysis reveals that the estimated degree of unsaturation mediates 0.69 % of the effect of Klebsiella pneumoniae on AN. Total lipids in small VLDL mediate 0.358 % of the effect of CAG-177 on AN, with a mediated proportion of 1.490 %. The mediation proportions for Estimated degree of unsaturation and Total lipids in small VLDL are relatively small. 36 immune cells have causal effects on AN. There are 7 protective factors, including Switched memory B cells %B cell (OR: 0.892，95%CI: 0.801-0.994, P = 0.038), CD127-CD8+ T cell absolute count (OR: 0.888，95%CI: 0.789-1.000, P = 0.049), IgD + CD24- B cell (OR: 0.917，95%CI: 0.862-0.975, P = 0.006), HVEM+ T cell (OR: 0.945，95%CI: 0.894-0.999, P = 0.045), CD40 + CD14 + CD16- monocyte (OR: 0.937，95%CI: 0.882-0.996, P = 0.038), CD64 + CD14 + CD16- monocyte (OR: 0.966，95%CI: 0.939-0.993, P = 0.016), CD8+ natural killer T cells (OR: 0.911，95%CI: 0.836-0.992, P = 0.032), HLA-DR+ T cells (OR: 0.921，95%CI: 0.866-0.980, P = 0.010), CD28-CD8+ T cells (OR: 0.886，95%CI: 0.792-0.991, P = 0.034). There are 26 risk factors. Reverse MR analysis showed that AN had a causal effect on 31 immune cells. AN increases the expression levels of five types of immune cells, including CD40 + CD14-CD16+ monocytes (OR: 1.087，95%CI: 1.004-1.177, P = 0.041), PDL-1+ CD14-CD16+ monocytes (OR: 1.082，95%CI: 1.002-1.168, P = 0.046), CD45+ CD33dim HLA-DR+ cells (OR: 1.145，95%CI: 1.019-1.287, P = 0.023), CD45+ basophils (OR: 1.164，95%CI: 1.036-1.307, P = 0.011), CD8+ natural killer T cells (OR: 1.102, 95%CI: 1.015-1.196, P = 0.020), and also decreases the expression levels of 26 immune cells. 6 liposomes showed exhibit protective effects against AN, including phosphatidylcholine (18:0_20:3) levels (OR: 0.852, 95%CI: 0.740-0.981, P = 0.026), phosphatidylcholine (O-18:2_18:1) levels (OR: 0.800, 95%CI: 0.672-0.952, P = 0.012), phosphatidylinositol (18:0_18:1) levels (OR: 0.873, 95%CI: 0.773-0.986, P = 0.029), phosphatidylinositol (18:1_18:2) levels (OR: 0.844, 95%CI: 0.734-0.971, P = 0.018), sphingomyelin (d38:1) levels (OR: 0.903，95%CI: 0.820-0.995, P = 0.039), and triacylglycerol (56:4) levels (OR: 0.786, 95%CI: 0.660-0.936, P = 0.007). There are 3 risk factors, including diacylglycerol (16:1_18:1) levels (OR: 1.208, 95%CI: 1.040-1.404, P = 0.014), phosphatidylcholine (18:1_18:3) levels (OR: 1.237, 95%CI: 1.003-1.526, P = 0.047), and phosphatidylinositol (16:0_20:4) levels (OR: 1.148, 95%CI: 1.003-1.314, P = 0.045). Reverse MR analysis showed that AN had a causal effect on 3 phosphatidylcholine (15:0_18:2) levels (OR: 1.075, 95%CI: 1.001-1.154, P = 0.048), phosphatidylcholine (O-16:2_18:0) levels (OR: 1.078, 95%CI: 1.002-1.159, P = 0.043), and triacylglycerol (51:1) levels (OR: 0.919, 95%CI: 0.850-0.994, P = 0.035). 6 inflammatory proteins have causal effects on AN, with protective factors including Glial cell line-derived neurotrophic factor levels (OR: 0.822，95%CI: 0.692-0.978, P = 0.027) and Interleukin-15 receptor subunit alpha levels (OR: 0.886, 95%CI: 0.789-0.995, P = 0.041) and risk factors including CC motif chemokine 4 levels (OR: 1.126, 95%CI: 1.011-1.254, P = 0.031), Interleukin-12 subunit beta levels (OR: 1.135, 95%CI: 1.033-1.248, P = 0.008), Monocyte chemoattractant protein-1 levels (OR: 1.152, 95%CI: 1.010-1.314, P = 0.035), and Sulfotransferase 1A1 levels (OR: 1.166, 95%CI: 1.006-1.351, P = 0.042). Reverse MR analysis showed that AN had a causal effect on Transforming growth factor-alpha (OR: 1.054，95%CI: 1.010-1.101, P = 0.016).

CONCLUSIONS

This study used large-scale and novel GWAS data, for the first time reveals through mediation analysis and multi-omics MR analysis the roles of gut microbiota, metabolites, immune cells, lipids, and inflammatory proteins in the pathogenesis of AN. These findings provide new biomarkers and targets for further prevention and treatment strategies.

Structural elucidation and functional characteristics of novel potential prebiotics produced from Limosilactobacillus reuteri N1 GtfB-treated maize starches

The recently characterized Limosilactobacillus reuteri N1 GtfB (LrN1 GtfB) from glycoside hydrolase family 70 is a novel 4,6-α-glucanotransferase acting on starch/maltooligosaccharides with high enzyme activity and soluble protein yield (in heterogenous system). In this study, the influence of the treatment by LrN1 GtfB on the fine structure and functional characteristics of three maize starches were furtherly investigated and elucidated. Due to the treatment of LrN1 GtfB, the starch molecules were transformed into reuterans containing linear and branched (α1 → 6) linkages with notably smaller molecular weight and shorter chain length. Moreover, the (α1 → 6) linkage ratios in the GtfB-modified high-amylose maize starch (GHMS)/normal maize starch (GNMS)/waxy maize starch (GWMS) increased by 18.3 %/12.6 %/9.0 % as compared to their corresponding controls. In vitro digestibility experiment revealed that the resistant starch content of GHMS, GNMS and GWMS increased by 16 %, 18 % and 25 % as compared to the starch substrates. Furthermore, the butyric acid yielded from GHMS, GNMS and GWMS in the in vitro fermentation experiments were 1.4, 1.5 and 1.4 times higher than those of commercial galactose oligosaccharides. These results indicated that the highly-branched short-clustered reuteran synthesized by LrN1 GtfB might serve as novel potential prebiotics, and provide insights for the synthesis of promising prebiotic dietary fiber from starch.

Functional Muffins Exert Bifidogenic Effects along with Highly Product-Specific Effects on the Human Gut Microbiota Ex Vivo

GoodBiome™ Foods are functional foods containing a probiotic (Bacillus subtilis HU58™) and prebiotics (mainly inulin). Their effects on the human gut microbiota were assessed using ex vivo SIFR® technology, which has been validated to provide clinically predictive insights. GoodBiome™ Foods (BBM/LCM/OSM) were subjected to oral, gastric, and small intestinal digestion/absorption, after which their impact on the gut microbiome of four adults was assessed (n = 3). All GoodBiome™ Foods boosted health-related SCFA acetate (+13.1/14.1/13.8 mM for BBM/LCM/OSM), propionate (particularly OSM; +7.4/7.5/8.9 mM for BBM/LCM/OSM) and butyrate (particularly BBM; +2.6/2.1/1.4 mM for BBM/LCM/OSM). This is related to the increase in Bifidobacterium species (B. catenulatum, B. adolescentis, B. pseudocatenulatum), Coprococcus catus and Bacteroidetes members (Bacteroides caccae, Phocaeicola dorei, P. massiliensis), likely mediated via inulin. Further, the potent propionogenic potential of OSM related to increased Bacteroidetes members known to ferment oats (s key ingredient of OSM), while the butyrogenic potential of BBM related to a specific increase in Anaerobutyricum hallii, a butyrate producer specialized in the fermentation of erythritol (key ingredient of BBM). In addition, OSM/BBM suppressed the pathogen Clostridioides difficile, potentially due to inclusion of HU58™ in GoodBiome™ Foods. Finally, all products enhanced a spectrum of metabolites well beyond SCFA, including vitamins (B3/B6), essential amino acids, and health-related metabolites such as indole-3-propionic acid. Overall, the addition of specific ingredients to complex foods was shown to specifically modulate the gut microbiome, potentially contributing to health benefits. Noticeably, our findings contradict a recent in vitro study, underscoring the critical role of employing a physiologically relevant digestion/absorption procedure for a more accurate evaluation of the microbiome-modulating potential of complex foods.

Effect of Polygonatum cyrtonema Hua polysaccharides on gluten structure, in vitro digestion and shelf-life of fresh wet noodle

This study aimed to investigate the effects of raw Polygonatum cyrtonema Hua polysaccharides (RPCPs) and "zhi" P. cyrtonema Hua polysaccharides (ZPCPs) on the gluten structure, in vitro digestion, and shelf life of fresh wet noodles (FWN). The results demonstrated that incorporating PCPs improved the cooking and sensory qualities of FWN. Moreover, the shelf life of FWN was extended by 6 days with 1.5 % RPCPs (w/w) compared with the control FWN. Furthermore, incorporating 1.5 % ZPCPs led to a 1.2- and 0.2-fold increase in the disulfide bond and α-helix content, respectively, compared with the control FWN. This resulted in enhanced gluten structure, improved springiness and viscidity, and reduced cooking loss by 14.47 %-52.19 %. The scanning electron microscopy analysis revealed that the starch particles were entrapped by PCPs, leading to higher gelatinization temperature and lower setback value of FWN, thereby reducing the starch digestion ratio to 55.50 %. In summary, the findings suggested that FWN containing PCPs can extend shelf life, improve taste, and slow starch digestion staple.

Exploiting the gut microbiome for brain tumour treatment

Increasing evidence suggests that the gut microbiome plays a key role in a host of pathological conditions, including cancer. Indeed, the bidirectional communication that occurs between the gut and the brain, known as the 'gut-brain axis,' has recently been implicated in brain tumour pathology. Here, we focus on current research that supports a gut microbiome-brain tumour link with emphasis on high-grade gliomas, the most aggressive of all brain tumours, and the impact on the glioma tumour microenvironment. We discuss the potential use of gut-brain axis signals to improve responses to current and future therapeutic approaches. We highlight that the success of novel treatment strategies may rely on patient-specific microbiome profiles, and these should be considered for personalised treatment approaches.

Lactic Acid Bacteria-Gut-Microbiota-Mediated Intervention towards Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), encompassing ulcerative colitis (UC) and Crohn's disease (CD), arises from intricate interactions involving genetics, environment, and pharmaceuticals with an ambiguous pathogenic mechanism. Recently, there has been an increasing utilization of lactic acid bacteria (LAB) in managing IBD, attributed to their ability to enhance intestinal barrier function, mitigate inflammatory responses, and modulate gut microbiota. This review initiates by elucidating the pathogenesis of IBD and its determinants, followed by an exploration of the mechanisms underlying LAB therapy in UC and CD. Special attention is directed towards their influence on intestinal barrier function and homeostasis regulated by gut microbiota. Furthermore, the review investigates the complex interplay among pivotal gut microbiota, metabolites, and pathways associated with inflammation. Moreover, it underscores the limitations of LAB in treating IBD, particularly in light of their varying roles in UC and CD. This comprehensive analysis endeavors to offer insights for the optimized application of LAB in IBD therapy.

Fecal bacteria and short-chain fatty acids in irritable bowel syndrome: Relations to subtype

BACKGROUND

The relationship between gut microbiota and irritable bowel syndrome (IBS) subtype is unclear. We aimed to explore whether differences in fecal bacteria composition and short-chain fatty acid (SCFA) levels were associated with subtypes and symptoms of IBS.

METHODS

All participants delivered fecal samples and self-reports on IBS Symptom Severity Score (IBS-SSS), Bristol Stool Scale (BSS), and Gastrointestinal Symptom Rating Scale (GSRS). Fecal bacteria composition was assessed by the GA-map® Dysbiosis Test based on 16S rRNA sequences of bacterial species/groups. SCFAs were analyzed by vacuum distillation followed by gas chromatography.

KEY RESULTS

Sixty patients with IBS were included (mean age 38 years, 46 [77%] females): Twenty-one patients were classified as IBS-D (diarrhea), 31 IBS-M (mixed diarrhea and constipation), and eight IBS-C (constipation). Forty-two healthy controls (HCs) (mean age 35 years, 27 [64%] females) were included. Patients had a significantly higher relative frequency of dysbiosis, lower levels of Actinobacteria, and higher levels of Bacilli than HCs. Eight bacterial markers were significantly different across IBS subgroups and HCs, and 13 bacterial markers were weakly correlated with IBS symptoms. Clostridia and Veillonella spp. had a weak negative correlation with constipation scores (GSRS) and a weak positive correlation with loose stools (BSS). Diarrhea scores (GSRS) and looser stool (BSS) were weakly correlated with levels of total SCFAs, acetic and butyric acid. Levels of total SCFAs and acetic acid were weakly correlated with symptom severity (IBS-SSS).

CONCLUSIONS & INFERENCES

Patients with IBS had a different fecal bacteria composition compared to HCs, and alterations of SCFAs may contribute to the subtype.

Modeling the effects of prebiotic interventions on luminal and mucosa-associated gut microbiota without and with Clostridium difficile challenge in vitro

Prebiotics can modulate the gut microbial community composition and function for improved (gut) health and increase resilience against infections. In vitro models of the gut facilitate the study of intervention effects on the gut microbial community relevant to health. The mucosa-associated gut microbiota, which thrives in close contact with the host plays a pivotal role in colonization resistance and health. Therefore, we here introduce the Mi-screen, an experimental approach implementing a 96-well plate equipped with a mucus agar layer for the additional culturing of mucosa-associated microbiota in vitro. In this study, we screened the effects of 2'-Fucosyllactose (2'-FL), fructooligosaccharides (FOS), and inulin within a complex microbiota without and with infection with the C. difficile strains ATCC 43599 (Ribotype 001) or ATCC BAA-1870 (Ribotype 027). We analyzed the microbial community composition and short-chain fatty acid levels after 48 h of incubation. The inclusion of an additional substrate and surface in the form of the mucus agar layer allowed us to culture a microbial richness ranging between 100-160 in Chao index, with Shannon indices of 5-6 across culture conditions, indicative of a microbial diversity of physiological relevance. The mucus agar layer stimulated the growth of characteristic mucosa-associated bacteria such as Roseburia inulinovorans. The prebiotic interventions affected luminal and mucosal microbial communities cultured in vitro and stimulated short-chain fatty acid production. FOS, inulin and 2'-FL promoted the growth of Bifidobacterium adolescentis within the mucosa-associated microbiota cultured in vitro. When spiking the untreated conditions with pathogenic C. difficile, the strains thrived within the luminal and the mucosal sample types, whereas prebiotic treatments exhibited inhibitory effects on C. difficile growth and prevented colonization. In conclusion, the Mi-screen facilitates the screening of luminal and mucosa-associated gut microbial community dynamics in vitro and therefore fills an important gap in the field of in vitro modeling.

Research advances in the therapy of metabolic syndrome

Metabolic syndrome refers to the pathological state of metabolic disorder of protein, fat, carbohydrate, and other substances in the human body. It is a syndrome composed of a group of complex metabolic disorders, whose pathogenesis includes multiple genetic and acquired entities falling under the category of insulin resistance and chronic low-grade inflammationand. It is a risk factor for increased prevalence and mortality from diabetes and cardiovascular disease. Cardiovascular diseases are the predominant cause of morbidity and mortality globally, thus it is imperative to investigate the impact of metabolic syndrome on alleviating this substantial disease burden. Despite the increasing number of scientists dedicating themselves to researching metabolic syndrome in recent decades, numerous aspects of this condition remain incompletely understood, leaving many questions unanswered. In this review, we present an epidemiological analysis of MetS, explore both traditional and novel pathogenesis, examine the pathophysiological repercussions of metabolic syndrome, summarize research advances, and elucidate the mechanisms underlying corresponding treatment approaches.

Dietary jack bean (Canavalia ensiformis L.) supplementation enhanced intestinal health by modulating intestinal integrity and immune responses of broiler chickens

This study investigated the influence of supplementing with jack beans on jejunal morphology, cecal short-chain fatty acids production, gene expression both of pro- and anti-inflammatory cytokines and tight junctions. Four treatment groups including 288 Indian River chicks that were one day old were randomized at random. While the treatment groups received jack bean supplementation at levels of 5 %, 10 %, and 15 %, the control group (0 %) was given a basal diet. For 11-35 days, each treatment consisted of 8 pens with 9 birds each. Supplementing with jack beans significantly enhanced butyrate production (P < 0.001), while at 10 % supplementation did not differ from control. Villus height (VH) and the ratio (VH:CD) were significantly (P < 0.001) increased by dietary treatments, while villus width (VW) and crypt depth (CD) were significantly (P < 0.05) decreased. TLR-3, TNF-a, and IL-6 were all significantly (P < 0.001) increased by dietary supplementation. However, at 15 %, TLR-3 and IL-6 were same with control. IL-18 was significantly (P < 0.05) decreased at 15 %. IL-10 decreased significantly (P < 0.001), but at 10 % same with control. At 5 and 10 %, IL-13 increased significantly (P < 0.001), whereas dietary treatments decreased at 15 % compared to control. Although ZO1 decreased significantly (P < 0.001) and OLCN increased significantly (P < 0.001), both ZO1 and OCLN were not significantly different from the control at 15 %. Dietary treatments significantly (P < 0.001) increased CLDN1 but did not differ from the control at 10 %. JAM2 decreased significantly (P < 0.001) with dietary treatments. In conclusion, jack bean supplementation may increase broiler chicken performance and intestinal health due to butyrate production. It may affect intestinal morphology and integrity by upregulating a tight junction protein gene. Jack beans also impacted jejunum immune responses and inflammatory cytokine gene expression.

Investigating the response of the butyrate production potential to major fibers in dietary intervention studies

Interventions involving dietary fibers are known to benefit host health. A leading contribution of gut microbiota is commonly recognized with production of short chain fatty acids (SCFA) suspected to play a key role. However, the detailed mechanisms are largely unknown, and apart from a well-described bifidogenic effect of some fibers, results for other bacterial taxa are often incongruent between studies. We performed pooled analyses of 16S rRNA gene data derived from intervention studies (n = 14) based on three fibers, namely, inulin-type fructans (ITF), resistant starch (RS), and arabinoxylan-oligosaccharides (AXOS), harmonizing the bioinformatics workflow to reveal taxa stimulated by those substrates, specifically focusing on the SCFA-production potential. The results showed an increased butyrate production potential after ITF (p < 0.05) and RS (p < 0.1) treatment via an increase in bacteria exhibiting the enzyme butyryl-CoA:acetate CoA-transferase (but) that was governed by Faecalibacterium, Anaerostipes (ITF) and Agathobacter (RS) respectively. AXOS did not promote an increase in butyrate producers, nor were pathways linked to propionate production stimulated by any intervention. A bifidogenic effect was observed for AXOS and ITF, which was only partly associated with the behavior of but-containing bacteria and largely represented a separate response. Low and high Ruminococcus abundances pre-intervention for ITF and RS, respectively, promoted an increase in but-containing taxa (p < 0.05) upon interventions, whereas initial Prevotella abundance was negatively associated with responses of butyrate producers for both fibers. Collectively, our data demonstrate targeted stimulation of specific taxa by individual fibers increasing the potential to synthesize butyrate, where gut microbiota composition pre-intervention strongly controlled outcomes.

Non-invasive VOCs detection to monitor the gut microbiota metabolism in-vitro

This work implemented a non-invasive volatile organic compounds (VOCs) monitoring approach to study how food components are metabolised by the gut microbiota in-vitro. The fermentability of a model food matrix rich in dietary fibre (oat bran), and a pure prebiotic (inulin), added to a minimal gut medium was compared by looking at global changes in the volatilome. The substrates were incubated with a stabilised human faecal inoculum over a 24-h period, and VOCs were monitored without interfering with biological processes. The fermentation was performed in nitrogen-filled vials, with controlled temperature, and tracked by automated headspace-solid-phase microextraction coupled with gas chromatography-mass spectrometry. To understand the molecular patterns over time, we applied a multivariate longitudinal statistical framework: repeated measurements-ANOVA simultaneous component analysis. The methodology was able to discriminate the studied groups by looking at VOCs temporal profiles. The volatilome showed a time-dependency that was more distinct after 12 h. Short to medium-chain fatty acids showed increased peak intensities, mainly for oat bran and for inulin, but with different kinetics. At the same time, alcohols, aldehydes, and esters showed distinct trends with discriminatory power. The proposed approach can be applied to study the intertwined pathways of gut microbiota food components interaction in-vitro.

Strategic exploration of whole grain cereals in modulating the glycaemic response

In the current context, diabetes presents itself as a widespread and complex global health issue. This study explores the significant influence of food microstructure and food matrix components interaction (protein, lipid, polyphenols, etc.) on the starch digestibility and the glycaemic response of post-prandial glycemia, focusing on the potential effectiveness of incorporating bioactive components from whole grain cereals into dietary strategies for the management and potential prevention of diabetes. This study aims to integrate the regulation of postprandial glycaemic homeostasis, including the complexities of starch digestion, the significant potential of bioactive whole grain components and the impact of food processing, to develop a comprehensive framework that combines these elements into a strategic approach to diabetes nutrition. The convergence of these nutritional strategies is analyzed in the context of various prevalent dietary patterns, with the objective of creating an accessible approach to mitigate and prevent diabetes. The objective remains to coalesce these nutritional paradigms into a coherent strategy that not only addresses the current public health crisis but also threads a preventative approach to mitigate future prevalence and impact.

The Role of Short Chain Fatty Acids in Inflammation and Body Health

Short chain fatty acids (SCFAs), mainly including acetate, propionate and butyrate, are produced by intestinal bacteria during the fermentation of partially digested and indigestible polysaccharides. SCFAs play an important role in regulating intestinal energy metabolism and maintaining the homeostasis of the intestinal environment and also play an important regulatory role in organs and tissues outside the gut. In recent years, many studies have shown that SCFAs can regulate inflammation and affect host health, and two main signaling mechanisms have also been identified: the activation of G-protein coupled receptors (GPCRs) and inhibition of histone deacetylase (HDAC). In addition, a growing body of evidence highlights the importance of every SCFA in influencing health maintenance and disease development. In this review, we summarized the recent advances concerning the biological properties of SCFAs and their signaling pathways in inflammation and body health. Hopefully, it can provide a systematic theoretical basis for the nutritional prevention and treatment of human diseases.

Associations between diet and nutritional supplements and colorectal cancer: A systematic review

Background and Aim

Colorectal cancer (CRC) is one of the most prevalent cancers around the world. The link between nutrients and the likelihood of developing CRC remains uncertain. The primary objective of the present study was to investigate the potential connection between dietary intake/dietary supplements and the occurrence of CRC through a literature review.

Methods

A comprehensive online search was conducted in PubMed, Scopus, Web of Science, and the Cochrane Library from January 1990 to March 2023 using appropriate keywords. A systematic search was conducted for clinical trials and cohort studies in order to determine the relationship between dietary components/supplements and CRC.

Results

The intake of long-chain n-3 polyunsaturated fatty acids (n-3 LCPUFAs), consisting of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), has the potential to decrease the likelihood of developing CRC (eight studies found positive effects and four studies found no association). Some other dietary components such as probiotics, prebiotics, and synbiotics may contribute to suppressing CRC development (three studies found positive effects, whereas three studies did not find any association). There is inconclusive evidence that supplementation with certain micronutrients including vitamin D (one trial found positive effects and another trial reported no association), folate, zinc, and selenium may reduce the risk of CRC.

Conclusion

Some dietary supplements such as n-3 LCPUFAs and probiotics have the potential to reduce the risk of developing CRC. Further studies are necessary to validate these results and understand the underlying mechanisms.

Interactive Effects of Dietary Fiber and Lipid Types Modulate the Predicted Production and Absorption of Cecal and Colorectal Short-Chain Fatty Acids in Growing Pigs

BACKGROUND

High-fiber diets are supplemented with lipids to meet the required energy content, but data on the interactions between dietary fiber (DF) and lipid types on gastrointestinal fermentation in pigs are scant.

OBJECTIVES

This study aimed to use a combination of in vivo and in vitro fermentation methodologies to determine the interactive effects of DF and lipid types on short-chain fatty acid (SCFA) production and absorption and organic matter (OM) fermentability in the cecum and colorectal tract of pigs.

METHODS

Eight ileal- and cecal-cannulated Yorkshire barrows were fed either pectin- or cellulose-containing diets that were supplemented with either corn oil or beef tallow in 2 independent Youden squares with a 2 × 2 factorial arrangement of treatments (n = 6). Ileal and cecal digesta were collected, freeze-dried, and fermented using inoculum from fresh cecal digesta and feces, respectively, to determine individual SCFA production and absorption and fermentability of OM.

RESULTS

Interactions (P < 0.001) between DF and lipid types were observed in which the addition of beef tallow decreased the quantity of cecal and colorectal acetic acid production and cecal acetic absorption, cecal butyric production, predicted cecal OM fermentability, and predicted colorectal propionic acid in pectin diets, but the effects were not observed for cellulose diets. The addition of beef tallow increased (P < 0.001) the production of cecal butyric and propionic acids during in vitro fermentation in cellulose diets and apparent total tract digestibility (ATTD) of OM in pectin diets.

CONCLUSIONS

The interactions between DF and lipids on gastrointestinal fermentation largely depend on the degree of saturation of fatty acids in dietary lipids. The addition of beef tallow selectively decreased the production and absorption of individual SCFAs in pectin and cellulose diets but increased cecal butyric and propionic acid production in cellulose diets and the ATTD of OM in pectin diets.

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.

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

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

Peyer's Patch: Possible target for modulating the Gut-Brain-Axis through microbiota

The gastrointestinal (GI) tract and the brain form bidirectional nervous, immune, and endocrine communications known as the gut-brain axis. Several factors can affect this axis; among them, various studies have focused on the microbiota and imply that alterations in microbiota combinations can influence both the brain and GI. Also, many studies have shown that the immune system has a vital role in varying gut microbiota combinations. In the current paper, we will review the multidirectional effects of gut microbiota, immune system, and nervous system on each other. Specifically, this review mainly focuses on the impact of Peyer's patches as a critical component of the gut immune system on the gut-brain axis through affecting the gut's microbial composition. In this way, some factors were discussed as proposed elements of missing gaps in this field.

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.

Elucidating Korean meadowsweet (Filipendula glaberrima Nakai)-derived arabinogalactan protein-induced macrophage activation and its associated mechanism of action

This study aimed to confirm macrophage-stimulatory component from Korean meadowsweet (Filipendula glaberrima; FG) and characterize its compositional and structural properties. FG-CWH, prepared via cool-water extraction and ethanol precipitation, induced the highest secretion of NO (6.0-8.0 μM), TNF-α (8.7-9.5 ng/mL), and IL-6 (1.0-5.7 ng/mL) compared to other samples at 0.4-10 μg/mL in RAW 264.7 cells. Analytical results revealed that FG-CWH is a high-molecular-weight component with an average molecular weight of 220 kDa, constituting a polysaccharide-protein mixture. Chemical and enzymatic treatment of FG-CWH indicated its primary composition as arabinogalactan protein (AGP)-rich glycoprotein, with activity likely associated with the chemical and structural characteristics of AGP. FG-CWH treatment resulted in significant and concentration-dependent increases in iNOS (20.0-29.6 folds), TNFα (10.6-18.6 folds) and IL6 (10.9-155.6 folds) gene expression, as well as the secretion of NO (5.3-6.3 μM), TNF-α (35.4-44.3 ng/mL), and IL-6 (4.1-8.4 ng/mL) secretion, even at a reduced concentration range of 125-500 ng/mL, compared to the negative control group. Immunoblotting analysis indicated FG-CWH-induced macrophage stimulation significantly associated with the activation of MAPK (ERK, JNK, and p38) and NF-κB (p65 and IκBα). These findings can serve as valuable groundwork for developing FG-derived AGP as novel functional ingredients to enhance human immunity.

Lentils pasta by-product in a complete extruded diet for dogs and its effect on extrusion, digestibility, and carbohydrate metabolism

Introduction

Recently, increasing effort has been directed toward environmental sustainability in pet food. The aim of this study was to evaluate the extrusion parameters, nutrient digestibility, fecal characteristics, palatability and insulinemic and glycaemic curves of a complete diet for dogs in which the main carbohydrate source was a red lentil pasta by-product (LP).

Methods

Five experimental diets were formulated: a basal diet (CO) based on rice and a poultry by-product meal; three experimental diets where LP substituted rice at 33, 66, or 100% (LP33, LP66, and LP100, respectively); and a diet formulated on 70% of the basal diet (CO) plus 30% LP (LPS) to evaluate the digestibility of LP ingredient.

Results and discussion

The extruder pressure, hardness and bulk density of the kibble increased in a linear manner with increasing LP percentage (P < 0.05), without affecting starch gelatinization. According to polynomial contrast analysis, rice replacement with LP at 33 and 66% caused no reduction in apparent total tract digestibility coefficient (ATTDC), with similar or higher values compared with the CO diet. Nitrogen balance did not change (P > 0.05), but we observed a linear increase in feces production and moisture content as the LP inclusion rate rose and a linear decrease in feces pH (P < 0.05). Nevertheless, the fecal score was unaffected. Fecal acetate, propionate, total short-chain fatty acids (SCFA), branched-chain fatty acids, and lactate all increased linearly as the LP inclusion rate increased (P < 0.05), without altering ammonia concentration in feces. Feces concentrations of cadaverine, tyramine, histamine, and spermidine also increased in a linear manner with increasing LP inclusion (P < 0.05). The fermentation of LP dietary fiber by the gut microbiota increased the concentration of desirable fermentation by-products, including SCFA and spermidine. The post-prandial glucose and insulin responses were lower in the dogs fed the LP100 diet compared with CO, suggesting the possible use of this ingredient in diets designed to generate a low glycaemic response. Finally, the palatability study results showed a preference for the LP100 ration in both the "first choice" and the "consumption rate" evaluation (P < 0.05). This trial reveals how a by-product discarded from the human-grade food chain retains both its nutritional and organoleptic properties.

Dietary risk factors for colorectal cancer in Uganda: a case-control study

INTRODUCTION

Low-income countries in East Africa have a lower incidence of colorectal cancer (CRC) than high-income countries; however, the incidence has steadily increased in the last few decades. In Uganda, the extent to which genetic and environmental factors, particularly dietary factors, contribute to the aetiology of CRC is unclear. Therefore, the objective of our study was to determine the relationship between dietary factors and CRC in Uganda.

METHODS

We conducted a case-control study and recruited 128 cases and 256 controls, matched for age (± 5 years) and sex. Data regarding the frequency of consumption of the dietary factors were obtained from all the participants using an interview-based questionnaire. The potential dietary risk factors and protective factors evaluated included the type and frequency of meat consumed and the type and frequency of high-fibre foods consumed. The frequency was either 4 or more times/week, 2-3 times/week, once/week or never. Conditional logistic regression analyses were used to determine the odds ratios associated with the different risk and protective factors.

RESULTS

The median age (IQR) for the case participants was 55.5 (43-67.5) years, and that of the control participants was 54 (42-65) years. The male-to-female ratio was 1:1 for all the participants. Factors significantly associated with CRC cases included:- the consumption of boiled beef 2-3 times/week (aOR:3.24; 95% CI: 1.08-9.69; p < 0.035). Consumption of high-fibre foods, including:- millet for ≥ 4 times/week (aOR: 0.23; 95% CI: 0.09-0.62; p = 0.003)), spinach for ≥ 4 times/week (aOR:0.32; 95% CI: 0.11-0.97; p = 0.043), and potatoes 2-3 times/week (aOR: 0.30; 95% CI: 0.09-0.97; p = 0.044), were protective against CRC. Boiled cassava showed a tendency to reduce the likelihood of CRC when consumed ≥ 4 times/week (aOR:0.38; 95% CI: 0.12-1.18) however this did not reach statistical significance (p = 0.093).

CONCLUSIONS

The consumption of boiled beef increases the risk of CRC, while the intake of high-fibre foods may reduce the risk of CRC among Ugandans. We recommend nutritional educational programmes to increase public awareness regarding the protective role of a high-fibre diet and to limit the intake of cooked meat in our Ugandan population.

Effects of germinated brown rice and germinated black rice on people with type 2 diabetes mellitus combined with dyslipidaemia

Objective: This study aimed to observe the effects of germinated brown rice and germinated black rice on blood lipid levels, blood glucose levels and lipid metabolism-related enzymes in T2DM patients with dyslipidaemia and to study their effects on the gut microbiome and short-chain fatty acids. Methods: According to the inclusion and exclusion criteria, 68 subjects were randomly divided into a germinated brown rice group, a germinated black rice group and a white rice group. At the end of the intervention, relevant anthropometric indices, blood biochemistry, and levels of adipokines and lipid metabolism-related enzymes were measured. Faecal samples were collected for 16S rDNA high-throughput sequencing and for an analysis of short-chain fatty acids. Results: After 3 months of intervention with germinated brown rice, germinated black rice or white rice, 21 people in each group completed the intervention as required. At the end of the intervention, the levels of total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) in the germinated brown rice group and germinated black rice group were significantly lower than those in the white rice group. The levels of adiponectin (ADPN) and lecithin cholesterol acyltransferase (LCAT) in the germinated brown rice group were significantly higher than those in the white rice group (P < 0.05). At the genus level, interventions with germinated brown rice and germinated black rice significantly increased the relative abundance of Megamonas, Muribaculaceae and Alloprevotella and significantly decreased the relative abundance of Veillonella (P < 0.05). After 3 months of intervention, a significant decrease in waist circumference was observed within the germinated brown rice group compared to that at baseline (P < 0.05). Conclusions: Compared with the consumption of white rice, the consumption of germinated brown rice and germinated black rice can effectively regulate the glucose and lipid metabolism of this population. In addition, interventions involving the use of germinated brown rice and germinated black rice may further improve intestinal diversity and abundance, increase the relative abundance of Megamonas and decrease the relative abundance of Veillonella.

Gut microbiome and cardiometabolic comorbidities in people living with HIV

BACKGROUND

Despite modern antiretroviral therapy (ART), people living with HIV (PLWH) have increased relative risk of inflammatory-driven comorbidities, including cardiovascular disease (CVD). The gut microbiome could be one of several driving factors, along with traditional risk factors and HIV-related risk factors such as coinfections, ART toxicity, and past immunodeficiency.

RESULTS

PLWH have an altered gut microbiome, even after adjustment for known confounding factors including sexual preference. The HIV-related microbiome has been associated with cardiometabolic comorbidities, and shares features with CVD-related microbiota profiles, in particular reduced capacity for short-chain fatty acid (SCFA) generation. Substantial inter-individual variation has so far been an obstacle for applying microbiota profiles for risk stratification. This review covers updated knowledge and recent advances in our understanding of the gut microbiome and comorbidities in PLWH, with specific focus on cardiometabolic comorbidities and inflammation. It covers a comprehensive overview of HIV-related and comorbidity-related dysbiosis, microbial translocation, and microbiota-derived metabolites. It also contains recent data from studies in PLWH on circulating metabolites related to comorbidities and underlying gut microbiota alterations, including circulating levels of the SCFA propionate, the histidine-analogue imidazole propionate, and the protective metabolite indole-3-propionic acid.

CONCLUSIONS

Despite recent advances, the gut microbiome and related metabolites are not yet established as biomarkers or therapeutic targets. The review gives directions for future research needed to advance the field into clinical practice, including promises and pitfalls for precision medicine. Video Abstract.

A Symbiotic Meal Containing Extruded Sorghum and Probiotic (Bifidobacterium longum) Ameliorated Intestinal Health Markers in Individuals with Chronic Kidney Disease: A Secondary Analysis of a Subsample from a Previous Randomized and Controlled Clinical Trial

BACKGROUND

Chronic kidney disease increases uremic toxins concentrations, which have been associated with intestinal dysbiosis. Sorghum bicolor L. Moench has dietary fiber and bioactive compounds, while Bifidobacterium longum can promote beneficial health effects.

METHODS

It is a controlled, randomized, and single-blind clinical trial. Thirty-nine subjects were randomly separated into two groups: symbiotic group (SG), which received 100 mL of unfermented probiotic milk with Bifidobacterium longum strain and 40 g of extruded sorghum flakes; and the control group (CG), which received 100 mL of pasteurized milk and 40 g of extruded corn flakes for seven weeks.

RESULTS

The uremic toxins decreased, and gastrointestinal symptoms improved intragroup in the SG group. The acetic, propionic, and butyric acid production increased intragroup in the SG group. Regarding α-diversity, the Chao1 index was enhanced in the SG intragroup. The KEGG analysis revealed that symbiotic meal increased the intragroup energy and amino sugar metabolism, in addition to enabling essential amino acid production and metabolism, sucrose degradation, and the biosynthesis of ribonucleotide metabolic pathways.

CONCLUSIONS

The consumption of symbiotic meal reduced BMI, improved short-chain fatty acid (SCFA) synthesis and gastrointestinal symptoms, increased diversity according to the Chao1 index, and reduced uremic toxins in chronic kidney disease patients.

Influence of Novel Microcapsulates of Bee Products on Gut Microbiota Modulation and Their Prebiotic and Pro-Adhesive Properties

With the aim to obtain controlled-release systems and to preserve the antioxidant, immunomodulatory, and prebiotic activity of the bioactive compounds, microencapsulation of both honeydew honey and royal jelly into biopolymeric microparticles based on rye bran heteropolysaccharides (HPS) was successfully performed. Honeydew honey and royal jelly microcapsules were prepared by spray-drying method and were characterized in terms of morphology and biological properties. Due to the resistance of the obtained encapsulates to the acidic pH in the stomach and digestive enzymes, the microcapsules showed prebiotic properties positively influencing both the growth, retardation of the dying phase, and the pro-adhesive properties of probiotic bacteria, i.e., Bifidobacterium spp. and lactic acid bacteria. Moreover, as a result of fermentation of the microcapsules of bee products in the lumen of the large intestine, an increased synthesis of short-chain fatty acids, i.e., butyric acid, was found on average by 39.2% in relation to the SCFA concentrations obtained as a result of fermentation of native bee products, thus opening new perspectives for the exploitation of honeydew honey and royal jelly loaded microcapsules for nutraceutical applications.

Pro-pre and Postbiotic Fermentation of the Dietetic Dairy Matrix with Prebiotic Sugar Replacers

In this study, bacterial growth, postbiotic short-chain fatty acids (SCFAs) formation, and gelation properties of sugar-free probiotic milk gels produced with stevia and inulin as a sugar replacer and synbiotic interactions were investigated with regard to prebiotic/bio-therapeutic potential and consumer preference. Lactobacillus acidophilus and Bifidobacterium animalis subsp. lactis cultures were used in the manufacture of dietetic milk gels. The addition of stevia and inulin promoted the viability of bacteria and enhanced milk gel firmness throughout its shelf life. The activity of the probiotic bacteria was identified to be within the potential prebiotic effects (> 8.30 log10 cfu mL-1) in a food matrix. However, it was determined that especially stevia and stevia + inulin addition increased the survival rate of probiotic bacteria and in vitro total SCFA production with higher scores for consumers' preferences rather than with the addition of stevia alone. Yoghurts containing B. animalis subsp. lactis have improved the instrumental textural properties, whereas yoghurts containing L. acidophilus had higher scores for sensorial attributes.

Relationship between gut microbiota and the pathogenesis of gestational diabetes mellitus: a systematic review

Introduction

Gestational diabetes mellitus (GDM) is a form of gestational diabetes mellitus characterized by insulin resistance and abnormal function of pancreatic beta cells. In recent years, genomic association studies have revealed risk and susceptibility genes associated with genetic susceptibility to GDM. However, genetic predisposition cannot explain the rising global incidence of GDM, which may be related to the increased influence of environmental factors, especially the gut microbiome. Studies have shown that gut microbiota is closely related to the occurrence and development of GDM. This paper reviews the relationship between gut microbiota and the pathological mechanism of GDM, in order to better understand the role of gut microbiota in GDM, and to provide a theoretical basis for clinical application of gut microbiota in the treatment of related diseases.

Methods

The current research results on the interaction between GDM and gut microbiota were collected and analyzed through literature review. Keywords such as "GDM", "gut microbiota" and "insulin resistance" were used for literature search, and the methodology, findings and potential impact on the pathophysiology of GDM were systematically evaluated.

Results

It was found that the composition and diversity of gut microbiota were significantly associated with the occurrence and development of GDM. Specifically, the abundance of certain gut bacteria is associated with an increased risk of GDM, while other changes in the microbiome may be associated with improved insulin sensitivity. In addition, alterations in the gut microbiota may affect blood glucose control through a variety of mechanisms, including the production of short-chain fatty acids, activation of inflammatory pathways, and metabolism of the B vitamin group.

Discussion

The results of this paper highlight the importance of gut microbiota in the pathogenesis of GDM. The regulation of the gut microbiota may provide new directions for the treatment of GDM, including improving insulin sensitivity and blood sugar control through the use of probiotics and prebiotics. However, more research is needed to confirm the generality and exact mechanisms of these findings and to explore potential clinical applications of the gut microbiota in the management of gestational diabetes. In addition, future studies should consider the interaction between environmental and genetic factors and how together they affect the risk of GDM.

Identification of carbohydrate gene clusters obtained from in vitro fermentations as predictive biomarkers of prebiotic responses

BACKGROUND

Prebiotic fibers are non-digestible substrates that modulate the gut microbiome by promoting expansion of microbes having the genetic and physiological potential to utilize those molecules. Although several prebiotic substrates have been consistently shown to provide health benefits in human clinical trials, responder and non-responder phenotypes are often reported. These observations had led to interest in identifying, a priori, prebiotic responders and non-responders as a basis for personalized nutrition. In this study, we conducted in vitro fecal enrichments and applied shotgun metagenomics and machine learning tools to identify microbial gene signatures from adult subjects that could be used to predict prebiotic responders and non-responders.

RESULTS

Using short chain fatty acids as a targeted response, we identified genetic features, consisting of carbohydrate active enzymes, transcription factors and sugar transporters, from metagenomic sequencing of in vitro fermentations for three prebiotic substrates: xylooligosacharides, fructooligosacharides, and inulin. A machine learning approach was then used to select substrate-specific gene signatures as predictive features. These features were found to be predictive for XOS responders with respect to SCFA production in an in vivo trial.

CONCLUSIONS

Our results confirm the bifidogenic effect of commonly used prebiotic substrates along with inter-individual microbial responses towards these substrates. We successfully trained classifiers for the prediction of prebiotic responders towards XOS and inulin with robust accuracy (≥ AUC 0.9) and demonstrated its utility in a human feeding trial. Overall, the findings from this study highlight the practical implementation of pre-intervention targeted profiling of individual microbiomes to stratify responders and non-responders.

Heme Metabolism Mediates the Effects of Smoking on Gut Microbiome

INTRODUCTION

The number of smokers worldwide increased greatly during the past decades and reached 1.14 billion in 2019, becoming a leading risk factor for human health. Tobacco smoking has wide effects on human genetics, epigenetics, transcriptome, and gut microbiome. Although many studies have revealed effects of smoking on host transcriptome, research on the relationship between smoking, host gene expression, and the gut microbiome is limited.

AIMS AND METHODS

We first explored transcriptome and metagenome profile differences between smokers and nonsmokers. To evaluate the relationship between host gene expression and gut microbiome, we then applied bidirectional mediation analysis to infer causal relationships between smoking, gene expression, and gut microbes.

RESULTS

Metagenome and transcriptome analyses revealed 71 differential species and 324 differential expressed genes between smokers and nonsmokers. With smoking as an exposure variable, we identified 272 significant causal relationships between gene expression and gut microbes, among which there were 247 genes that mediate the effect of smoking on gut microbes. Pathway-based enrichment analysis showed that these genes were significantly enriched in heme metabolic pathway, which mainly mediated the changes of Bacteroides finegoldii and Lachnospiraceae bacterium 9_1_43BFAA. Additionally, by performing metabolome data analysis in the Integrated Human Microbiome Project (iHMP) database, we verified the correlation between the intermediate products of the heme metabolism pathway (porphobilinogen, bilirubin, and biliverdin) and gut microbiome.

CONCLUSIONS

By investigating the bidirectional interaction between smoking-related host gene expression and gut microbes, this study provided evidence for the mediation of smoking on gut microbes through co-involvement or interaction of heme metabolism.

IMPLICATIONS

By comparing the metagenome and transcriptome sequencing profiles between 34 smokers and 33 age- and gender-matched nonsmokers, we are the first to reveal causal relationships among tobacco smoking, host gene expression, and gut microbes. These findings offer insight into how smoking affects gut microbes through host gene expression and metabolism, which highlights the importance of heme metabolism in modulating the effects of smoking on gut microbiome.

The effect of fecal microbiota transplantation on antibiotic-associated diarrhea and its impact on gut microbiota

BACKGROUND

Antibiotic-associated diarrhea (AAD) refers to symptoms of diarrhea that cannot be explained by other causes after the use of antibiotics. AAD is thought to be caused by a disruption of intestinal ecology due to antibiotics. Fecal Microbiota Transplantation (FMT) is a treatment method that involves transferring microbial communities from the feces of healthy individuals into the patient's gut.

METHOD

We selected 23 AAD patients who received FMT treatment in our department. Before FMT, we documented patients' bowel movement frequency, abdominal symptoms, routine blood tests, and inflammatory markers, and collected fecal samples for 16S rRNA sequencing to observe changes in the intestinal microbiota. Patients' treatment outcomes were followed up 1 month and 3 months after FMT.

RESULTS

Out of the 23 AAD patients, 19 showed a clinical response to FMT with alleviation of abdominal symptoms. Among them, 82.61% (19/23) experienced relief from diarrhea, 65% (13/20) from abdominal pain, 77.78% (14/18) from abdominal distension, and 57.14% (4/7) from bloody stools within 1 month after FMT. Inflammatory markers IL-8 and CRP significantly decreased after FMT, but there were no noticeable changes in WBC, IL-6, and TNF-α before and after transplantation. After FMT, the abundance of Bacteroides and Faecalibacterium increased in patients' fecal samples, while the abundance of Escherichia-Shigella and Veillonella decreased.

CONCLUSION

FMT has a certain therapeutic effect on AAD, and can alleviate abdominal symptoms and change the intestinal microbiota of patients.

Short-Chain Fatty Acid Butyrate Is an Inotropic Agent With Vasorelaxant and Cardioprotective Properties

BACKGROUND

The heart can metabolize the microbiota-derived short-chain fatty acid butyrate. Butyrate may have beneficial effects in heart failure, but the underlying mechanisms are unknown. We tested the hypothesis that butyrate elevates cardiac output by mechanisms involving direct stimulation of cardiac contractility and vasorelaxation in rats.

METHODS AND RESULTS

We examined the effects of butyrate on (1) in vivo hemodynamics using parallel echocardiographic and invasive blood pressure measurements, (2) isolated perfused hearts in Langendorff systems under physiological conditions and after ischemia and reperfusion, and (3) isolated coronary arteries mounted in isometric wire myographs. We tested Na-butyrate added to injection solutions or physiological buffers and compared its effects with equimolar doses of NaCl. Butyrate at plasma concentrations of 0.56 mM increased cardiac output by 48.8±14.9%, stroke volume by 38.5±12.1%, and left ventricular ejection fraction by 39.6±6.2%, and lowered systemic vascular resistance by 33.5±6.4% without affecting blood pressure or heart rate in vivo. In the range between 0.1 and 5 mM, butyrate increased left ventricular systolic pressure by up to 23.7±3.4% in isolated perfused hearts and by 9.4±2.9% following ischemia and reperfusion, while reducing myocardial infarct size by 81.7±16.9%. Butyrate relaxed isolated coronary septal arteries concentration dependently with an EC50=0.57 mM (95% CI, 0.23-1.44).

CONCLUSIONS

We conclude that butyrate elevates cardiac output through mechanisms involving increased cardiac contractility and vasorelaxation. This effect of butyrate was not associated with adverse myocardial injury in damaged hearts exposed to ischemia and reperfusion.

In vitro and in vivo fermentation models to study the function of dietary fiber in pig nutrition

The importance of dietary fiber (DF) in animal diets is increasing with the advancement of nutritional research. DF is fermented by gut microbiota to produce metabolites, which are important in improving intestinal health. This review is a systematic review of DF in pig nutrition using in vitro and in vivo models. The fermentation characteristics of DF and the metabolic mechanisms of its metabolites were summarized in an in vitro model, and it was pointed out that SCFAs and gases are the important metabolites connecting DF, gut microbiota, and intestinal health, and they play a key role in intestinal health. At the same time, some information about host-microbe interactions could have been improved through traditional animal in vivo models, and the most direct feedback on nutrients was generated, confirming the beneficial effects of DF on sow reproductive performance, piglet intestinal health, and growing pork quality. Finally, the advantages and disadvantages of different fermentation models were compared. In future studies, it is necessary to flexibly combine in vivo and in vitro fermentation models to profoundly investigate the mechanism of DF on the organism in order to promote the development of precision nutrition tools and to provide a scientific basis for the in-depth and rational utilization of DF in animal husbandry. KEY POINTS: • The fermentation characteristics of dietary fiber in vitro models were reviewed. • Metabolic pathways of metabolites and their roles in the intestine were reviewed. • The role of dietary fiber in pigs at different stages was reviewed.

Effect of Stool Sampling on a Routine Clinical Method for the Quantification of Six Short Chain Fatty Acids in Stool Using Gas Chromatography-Mass Spectrometry

Short chain fatty acids (SCFAs) are primarily produced in the caecum and proximal colon via the bacterial fermentation of undigested carbohydrates that have avoided digestion in the small intestine. Increasing evidence supports the critical role that SCFAs play in health and homeostasis. Microbial SCFAs, namely butyric acid, serve as a principal energy source for colonocytes, and their production is essential for gut integrity. A direct link between SCFAs and some human pathological conditions, such as inflammatory bowel disease, irritable bowel syndrome, diarrhea, and cancer, has been proposed. The direct measurement of SCFAs in feces provides a non-invasive approach to demonstrating connections between SCFAs, microbiota, and metabolic diseases to estimate their potential applicability as meaningful biomarkers of intestinal health. This study aimed to adapt a robust analytical method (liquid-liquid extraction, followed by isobutyl chloroformate derivatization and GC-MS analysis), with comparable performances to methods from the literature, and to use this tool to tackle the question of pre-analytical conditions, namely stool processing. We focused on the methodology of managing stool samples before the analysis (fresh stool or dilution in either ethanol/methanol, lyophilized stool, or RNAlater®), as this is a significant issue to consider for standardizing results between clinical laboratories. The objective was to standardize methods for future applications as diagnostic tools. In this paper, we propose a validated GC-MS method for SCFA quantification in stool samples, including pre- and post-analytical comparison studies that could be easily used for clinical laboratory purposes. Our results show that using lyophilization as a stool-processing method would be the best method to achieve this goal.

Integrated Metabolomics and Proteomics of Symptomatic and Early Presymptomatic States of Colitis

Colitis has a multifactorial pathogenesis with a strong cross-talk among microbiota, hypoxia, and tissue metabolism. Here, we aimed to characterize the molecular signature of the disease in symptomatic and presymptomatic stages of the inflammatory process at the tissue and fecal level. The study is based on two different murine models for colitis, and HR-MAS NMR on "intact" colon tissues and LC-MS/MS on colon tissue extracts were used to derive untargeted metabolomics and proteomics information, respectively. Solution NMR was used to derive metabolomic profiles of the fecal extracts. By combining metabolomic and proteomic analyses of the tissues, we found increased anaerobic glycolysis, accompanied by an altered citric acid cycle and oxidative phosphorylation in inflamed colons; these changes associate with inflammation-induced hypoxia taking place in colon tissues. Different colitis states were also characterized by significantly different metabolomic profiles of fecal extracts, attributable to both the dysbiosis characteristic of colitis as well as the dysregulated tissue metabolism. Strong and distinctive tissue and fecal metabolomic signatures can be detected before the onset of symptoms. Therefore, untargeted metabolomics of tissues and fecal extracts provides a comprehensive picture of the changes accompanying the disease onset already at preclinical stages, highlighting the diagnostic potential of global metabolomics for inflammatory diseases.

Short-Chain Fatty Acid (SCFA) as a Connecting Link between Microbiota and Gut-Lung Axis-A Potential Therapeutic Intervention to Improve Lung Health

The microbiome is an integral part of the human gut, and it plays a crucial role in the development of the immune system and homeostasis. Apart from the gut microbiome, the airway microbial community also forms a distinct and crucial part of the human microbiota. Furthermore, several studies indicate the existence of communication between the gut microbiome and their metabolites with the lung airways, called "gut-lung axis". Perturbations in gut microbiota composition, termed dysbiosis, can have acute and chronic effects on the pathophysiology of lung diseases. Microbes and their metabolites in lung stimulate various innate immune pathways, which modulate the expression of the inflammatory genes in pulmonary leukocytes. For instance, gut microbiota-derived metabolites such as short-chain fatty acids can suppress lung inflammation through the activation of G protein-coupled receptors (free fatty acid receptors) and can also inhibit histone deacetylase, which in turn influences the severity of acute and chronic respiratory diseases. Thus, modulation of the gut microbiome composition through probiotic/prebiotic usage and fecal microbiota transplantation can lead to alterations in lung homeostasis and immunity. The resulting manipulation of immune cells function through microbiota and their key metabolites paves the way for the development of novel therapeutic strategies in improving the lung health of individuals affected with various lung diseases including SARS-CoV-2. This review will shed light upon the mechanistic aspect of immune system programming through gut and lung microbiota and exploration of the relationship between gut-lung microbiome and also highlight the therapeutic potential of gut microbiota-derived metabolites in the management of respiratory diseases.