Gut Microbiota Prevents Sugar Alcohol-Induced Diarrhea

Online monitored characterization of Phocaeicola vulgatus for organic acid production using anaerobic microtiter plate cultivations

Phocaeicola vulgatus (formerly Bacteroides vulgatus), an anaerobic gut bacterium, produces several organic acids. Research on P. vulgatus is still in its infancy. However, a detailed understanding of P. vulgatus growth and metabolism is essential for its assessment as an organic acid producer. Media variations, including different initial glucose and NH4Cl concentrations and osmolalities, are significant means to yield higher organic acid titers. Furthermore, examining different nitrogen and carbon sources is important to evaluate the potential of P. vulgatus for growth on renewable resources. Cultivations were performed in an in-house built device for anaerobic online-monitoring of fluorescence and scattered light in microtiter plates. Results revealed that the highest organic acid concentrations were reached while using galactose, glucose, or xylose as a carbon source, high osmolalities, and 0.25 g L-1 NH4Cl. In addition, the organic acid composition changed with changing carbon and nitrogen sources. P. vulgatus was successfully further characterized, thereby contributing to a faster characterization of other anaerobic strains and paving the way for anaerobic organic acid production.

Artificial sweeteners and Type 2 Diabetes Mellitus: A review of current developments and future research directions

While artificial sweeteners are Generally Regarded as Safe (GRAS), the scientific community remains divided on their safety status. The previous assumption that artificial sweeteners are inert within the body is no longer valid. Artificial sweeteners, known for their high intense sweetness and low or zero calories, are extensively used today in food and beverage products as sugar substitutes and are sometimes recommended for weight management and Type 2 Diabetes Mellitus (T2DM) patients. The general omission of information about the concentration of artificial sweeteners on market product labels makes it challenging to determine the amounts of artificial sweeteners consumed by people. Despite regulatory authorization for their usage, such as from the United States Food and Drug Administration (FDA), concerns remain about their potential association with metabolic diseases, such as T2DM, which the artificial sweeteners were supposed to reduce. This review discusses the relationship between artificial sweetener consumption and the risk of developing T2DM. With the increasing number of recent scientific studies adding to the debate on this subject matter, we assessed recent literature and up-to-date evidence. Importantly, we highlight future research directions toward furthering knowledge in this field of study.

The human gut microbiome in health and disease: time for a new chapter?

The gut microbiome, composed of the colonic microbiota and their host environment, is important for many aspects of human health. A gut microbiome imbalance (gut dysbiosis) is associated with major causes of human morbidity and mortality. Despite the central part our gut microbiome plays in health and disease, mechanisms that maintain homeostasis and properties that demarcate dysbiosis remain largely undefined. Here we discuss that sorting taxa into meaningful ecological units reveals that the availability of respiratory electron acceptors, such as oxygen, in the host environment has a dominant influence on gut microbiome health. During homeostasis, host functions that limit the diffusion of oxygen into the colonic lumen shelter a microbial community dominated by primary fermenters from atmospheric oxygen. In turn, primary fermenters break down unabsorbed nutrients into fermentation products that support host nutrition. This symbiotic relationship is disrupted when host functions that limit the luminal availability of host-derived electron acceptors become weakened. The resulting changes in the host environment drive alterations in the microbiota composition, which feature an elevated abundance of facultatively anaerobic microbes. Thus, the part of the gut microbiome that becomes imbalanced during dysbiosis is the host environment, whereas changes in the microbiota composition are secondary to this underlying cause. This shift in our understanding of dysbiosis provides a novel starting point for therapeutic strategies to restore microbiome health. Such strategies can either target the microbes through metabolism-based editing or strengthen the host functions that control their environment.

Gut Microbial Utilization of the Alternative Sweetener, D-Allulose, via AlsE

D-allulose, a rare sugar with emerging potential as a low-calorie sweetener, has garnered attention as an alternative to other commercially available alternative sweeteners, such as sugar alcohols, which often cause severe gastrointestinal discomfort. D-allulose-6-phosphate 3-epimerase (AlsE) is a prokaryotic enzyme that converts D-allulose-6-phosphate into D-fructose-6-phopshate, enabling its use as a carbon source. However, the taxonomic breadth of AlsE across gut bacteria remains poorly understood, hindering insights into the utilization of D-allulose by microbial communities. In this study, we provide experimental evidence showing that Clostridium innocuum is capable of D-allulose metabolism via a homologous AlsE. A bioinformatics search of 85,202 bacterial genomes identified 116 bacterial species with AlsE homologs, suggesting a limited distribution of AlsE in bacteria. Additionally, Escherichia coli contains a copy of alsE , but it does not grow on D-allulose as a sole carbon source unless alsE is heterologously expressed. A metagenomic analysis revealed that 15.8% of 3,079 adult healthy human metagenomic samples that we analyzed contained alsE , suggesting a limited prevalence of the enzyme in the gut microbiome. These results suggest that the gut microbiome has limited capacity to metabolize D-allulose via alsE , supporting its use as an alternative sweetener with minimal impact on microbial composition and gastrointestinal symptoms. This finding also enables personalized nutrition, allowing diabetic individuals to assess their gut microbiota for alsE , and manage glycemic response while reducing gastrointestinal distress.

The protective effect of dulcitol on lipopolysaccharide-induced intestinal injury in piglets: mechanistic insights

This study investigated the protective effect of dulcitol on LPS-induced intestinal injury in piglets and explored the underlying molecular mechanisms. A total of 108 piglets were divided into three groups: CON, LPS, and DUL. The CON and LPS groups were fed a basal diet, the DUL group was fed a diet supplementation with 500 mg/kg dulcitol. On day 29, 6 piglets in the LPS and DUL groups were injected with 100 μg/kg BW of LPS. At 4 h postchallenge, all pigs were slaughtered, and colonic samples were collected. Results showed that dulcitol supplementation boosted intestinal barrier function in LPS-challenged piglets by enhancing intestinal morphology and integrity, and increasing the gene expression of zonula occludens-1, claudin-1, and occludin in the colonic mucosa (P <0.05). Metabolomics showed DUL supplementation mainly increased (P <0.05) the metabolites related to steroid and vitamin metabolism (Cholesterol and Vitamin C). Proteomics showed that dulcitol supplementation altered the protein expression involved in maintaining barrier integrity (FN1, CADM1, and PARD3), inhibiting inflammatory response (SLP1, SFN, and IRF3), and apoptosis (including FAS, ING1, BTK, MTHFR, NOX, and P53BP2) in LPS-challenged piglets (P <0.05). Additionally, dulcitol addition also suppressed the TLR4/NF-κB signaling pathway and apoptosis in mRNA and protein levels. Dulcitol increased the abundance of short-chain fatty acid-producing bacteria (Lactobacillus, Blautia, and Faecalibacterium) at the genus level, but decreased the relative abundance of Proteobacteria at the phylum level and Pseudomonas and Delftia at the genus level in piglets (P<.05). In conclusion, these results suggested that the addition of dulcitol alleviated LPS-induced intestinal barrier injury in piglets, probably by maintaining its integrity, inhibiting the TLR4/NF-κB signaling pathways and apoptosis, and modulating the gut microbiota. Therefore, dulcitol can be considered a potential dietary additive for improving intestinal health in pig models.

Host-diet-microbiota interplay in intestinal nutrition and health

The intestine is populated by a complex and dynamic assortment of microbes, collectively called gut microbiota, that interact with the host and contribute to its metabolism and physiology. Diet is considered a key regulator of intestinal microbiota, as ingested nutrients interact with and shape the resident microbiota composition. Furthermore, recent studies underscore the interplay of dietary and microbiota-derived nutrients, which directly impinge on intestinal stem cells regulating their turnover to ensure a healthy gut barrier. Although advanced sequencing methodologies have allowed the characterization of the human gut microbiome, mechanistic studies assessing diet-microbiota-host interactions depend on the use of genetically tractable models, such as Drosophila melanogaster. In this review, we first discuss the similarities between the human and fly intestines and then we focus on the effects of diet and microbiota on nutrient-sensing signaling cascades controlling intestinal stem cell self-renewal and differentiation, as well as disease. Finally, we underline the use of the Drosophila model in assessing the role of microbiota in gut-related pathologies and in understanding the mechanisms that mediate different whole-body manifestations of gut dysfunction.

Recommendations for the management of gastrointestinal comorbidities with or without trofinetide use in Rett syndrome

INTRODUCTION

Although gastrointestinal (GI) comorbidities are experienced by over 90% of individuals with Rett syndrome (RTT), a neurodevelopmental disorder associated with mutations in the MECP2 gene, many neurologists and pediatricians do not rank the management of these comorbidities among the most important treatment goals for RTT. Trofinetide, the first approved pharmacologic treatment for RTT, confers improvements in RTT symptoms but is associated with adverse GI events, primarily diarrhea and vomiting. Treatment strategies for GI comorbidities and drug-associated symptoms in RTT represent an unmet clinical need.

AREAS COVERED

This perspective covers GI comorbidities experienced by those with RTT, either with or without trofinetide treatment. PubMed literature searches were undertaken on treatment recommendations for the following conditions: constipation, diarrhea, vomiting, aspiration, dysphagia, gastroesophageal reflux, nausea, gastroparesis, gastritis, and abdominal bloating.

EXPERT OPINION

The authors recommend a proactive approach to management of symptomatic GI comorbidities and drug-associated symptoms in RTT to enhance drug tolerance and improve the quality of life of affected individuals. Management strategies for common GI comorbidities associated with RTT are reviewed based on authors' clinical experience and augmented by recommendations from the literature.

Bibliometric Analysis of Clinical Trials on the Effect of Sugar Alcohol Consumption on Oral Health: Trends, Insights, and Future Directions (1967-2024)

In recent years, the quest for healthier alternatives to sugar has led to the widespread use of sugar alcohol in various food and beverage products. Sugar alcohols, such as xylitol, sorbitol, and erythritol, are popular substitutes due to their sweet taste and lower calorie content than sucrose. Beyond their role in calorie reduction, sugar alcohols have garnered attention for their potential impact on oral health. The bibliometric analysis of clinical trials on sugar alcohol and oral health in PubMed reveals a dynamic and multifaceted research landscape shaped by various factors. Fluctuations in publication rates over time suggest influences such as shifts in research interests, technological advancements, regulatory changes, and evolving consumer behaviors. Key authors like Makinen KK, Makinen PL, and Soderling E emerge as prolific contributors with collaborative solid networks within the research community. The University of Turku in Finland has been identified as the highest contributing university, while Caries Research is the most contributing journal based on the number of clinical trials published. The country-wise analysis highlights Italy and the United States as substantial contributors, with diverse trajectories of research activity observed across nations. The subject-specific words with the highest cooccurrence are xylitol, dental caries, chewing gum, Streptococcus mutans, and saliva. Thematic analysis dives deep into how sugar alcohols relate to oral health, using different methods to study their effectiveness, safety, and how they affect the oral microbiome. The analysis of topic trends indicates ongoing exploration of sorbitol and xylitol, with an increasing emphasis on the potential advantages of xylitol. Additionally, there is notable attention on cariostatic agents, strategies for dental caries prevention, and the emergence of novel research domains like probiotics and erythritol, showcasing the dynamic evolution of oral health research focuses and developments. Overall, this analysis provides valuable insights into the distribution and trends of clinical trial publications, contributing to a nuanced understanding of the research landscape in sugar alcohol and oral health.

High fat intake sustains sorbitol intolerance after antibiotic-mediated Clostridia depletion from the gut microbiota

Carbohydrate intolerance, commonly linked to the consumption of lactose, fructose, or sorbitol, affects up to 30% of the population in high-income countries. Although sorbitol intolerance is attributed to malabsorption, the underlying mechanism remains unresolved. Here, we show that a history of antibiotic exposure combined with high fat intake triggered long-lasting sorbitol intolerance in mice by reducing Clostridia abundance, which impaired microbial sorbitol catabolism. The restoration of sorbitol catabolism by inoculation with probiotic Escherichia coli protected mice against sorbitol intolerance but did not restore Clostridia abundance. Inoculation with the butyrate producer Anaerostipes caccae restored a normal Clostridia abundance, which protected mice against sorbitol-induced diarrhea even when the probiotic was cleared. Butyrate restored Clostridia abundance by stimulating epithelial peroxisome proliferator-activated receptor-gamma (PPAR-γ) signaling to restore epithelial hypoxia in the colon. Collectively, these mechanistic insights identify microbial sorbitol catabolism as a potential target for approaches for the diagnosis, treatment, and prevention of sorbitol intolerance.

Gut dysbiosis: Ecological causes and causative effects on human disease

The gut microbiota plays a role in many human diseases, but high-throughput sequence analysis does not provide a straightforward path for defining healthy microbial communities. Therefore, understanding mechanisms that drive compositional changes during disease (gut dysbiosis) continues to be a central goal in microbiome research. Insights from the microbial pathogenesis field show that an ecological cause for gut dysbiosis is an increased availability of host-derived respiratory electron acceptors, which are dominant drivers of microbial community composition. Similar changes in the host environment also drive gut dysbiosis in several chronic human illnesses, and a better understanding of the underlying mechanisms informs approaches to causatively link compositional changes in the gut microbiota to an exacerbation of symptoms. The emerging picture suggests that homeostasis is maintained by host functions that control the availability of resources governing microbial growth. Defining dysbiosis as a weakening of these host functions directs attention to the underlying cause and identifies potential targets for therapeutic intervention.

Trehalose Inhibits Inflammatory Responses through Mitochondrial Reprogramming in RAW 264.7 Macrophages

Studies reported the beneficial effects of trehalose on metabolic syndromes, hyperlipidemia, and autophagy, but its action mechanisms are still poorly understood. Even though trehalose is digested by disaccharidase and absorbed in the intestine, intact molecules encounter immune cells which form a solid balance between the allowance of nutritive substances and the removal of harmful pathogens. In this regard, the polarization of intestinal macrophages into an anti-inflammatory phenotype through metabolic regulation is emerging as a therapeutic strategy for the prevention of gastrointestinal inflammation. The current study investigated the effects of trehalose on immunological phenotypes, energy metabolism, and LPS-induced macrophage mitochondrial functioning. Results indicate that trehalose reduces prostaglandin E₂ and nitric oxide, which are inflammatory mediators of LPS-induced macrophages. In addition, trehalose further significantly suppressed inflammatory cytokines and mediators via energy metabolism reprogramming towards M2-like status in LPS-stimulated macrophages.

The Impact of Food Additives on the Abundance and Composition of Gut Microbiota

The gut microbiota has been confirmed as an important part in human health, and is even take as an 'organ'. The interaction between the gut microbiota and host intestinal environment plays a key role in digestion, metabolism, immunity, inflammation, and diseases. The dietary component is a major factor that affects the composition and function of gut microbiota. Food additives have been widely used to improve the color, taste, aroma, texture, and nutritional quality of processed food. The increasing variety and quantity of processed food in diets lead to increased frequency and dose of food additives exposure, especially artificial food additives, which has become a concern of consumers. There are studies focusing on the impact of food additives on the gut microbiota, as long-term exposure to food additives could induce changes in the microbes, and the gut microbiota is related to human health and disease. Therefore, the aim of this review is to summarize the interaction between the gut microbiota and food additives.

Effects of sweeteners on host physiology by intestinal mucosal microbiota: Example-addition sweeteners in Qiweibaizhu Powder on intestinal mucosal microbiota of mice with antibiotic-associated diarrhea

In recent years, sweeteners have gained massive popularity under the trend of limiting sugar intake. Our previous study found that Qiweibaizhu Powder (QWBZP) could improve gut microbiota dysbiosis and has good efficacy in treating antibiotic-associated diarrhea (AAD). In this study, we investigated the effects of sucrose, sorbitol, xylitol, and saccharin on the intestinal mucosal microbiota of AAD mice treated with QWBZP. When the AAD model was constructed by being gavaged mixed antibiotic solution, Kunming mice were randomly assigned to seven groups: the control (mn) group, the ADD (mm) group, the QWBZP (mq) group, the saccharin + QWBZP (mc) group, the sucrose + QWBZP (ms) group, the xylito + QWBZP (mx) group, and the sorbitol + QWBZP (msl) group. Subsequently, 16S rRNA gene amplicon sequencing was used to analyze the intestinal mucosal microbiota composition and abundance. The results showed that feces from AAD mice were diluted and wet and improved diarrhea symptoms with QWBZP and sorbitol. In contrast, the addition of sucrose, saccharin, and xylitol delayed the healing of diarrhea. The relative abundance of intestinal mucosal microbiota showed Glutamicibacter, Robinsoniella, and Blautia were characteristic bacteria of the mx group, Candidatus Arthromitus, and Bacteroidales_S24-7_group as the typical bacteria of the mn group, Clostridium_innocuum_group as the distinct bacteria of the mm group. Mycoplasma and Bifidobacterium as the characteristic bacteria of the ms group. Correlation analysis of typical bacterial genera with metabolic functions shows that Blautia negatively correlates with D-Glutamine and D-glutamate metabolism. Bacteroidales_S24-7_group has a significant negative correlation with the Synthesis and degradation of ketone bodies. The study confirmed that sucrose, sorbitol, xylitol, and saccharin might further influence metabolic function by altering the intestinal mucosal microbiota. Compared to the other sweetener, adding sorbitol to QWBZP was the best therapeutic effect for AAD and increased the biosynthesis and degradation activities. It provides the experimental basis for applying artificial sweeteners in traditional Chinese medicine (TCM) as a reference for further rational development and safe use of artificial sweeteners.