Gut microbiota and vitamin status in persons with obesity: A key interplay

The Obesogenic Gut Microbiota as a Crucial Factor Defining the Depletion of Predicted Enzyme Abundance for Vitamin B12 Synthesis in the Mouse Intestine

Currently, obesity is a critical global public health burden. Numerous studies have demonstrated the regulation of the pathogenesis of obesity and metabolic abnormalities by the gut microbiota and microbial factors; however, their involvement in the various degrees of obesity is not yet well understood. Previously, obesity has been shown to be associated with decreased levels of vitamin B12. Considering exclusive microbial production of vitamin B12, we hypothesized that a decrease in cobalamin levels in obese individuals may be at least partially caused by its depleted production in the intestinal tract by the commensal microbiota. In the present study, our aim was to estimate the abundance of enzymes and metabolic pathways for vitamin B12 synthesis in the gut microbiota of mouse models of alimentary and genetically determined obesity, to evaluate the contribution of the obesogenic microbiome to vitamin B12 synthesis in the gut. We have defined a significantly lower predicted abundance of enzymes and metabolic pathways for vitamin B12 biosynthesis in obese mice compared to non-obese mice, wherein enzyme depletion was more pronounced in lepr(-/-) (db/db) mice, which developed severe obesity. The predicted abundance of enzymes involved in cobalamin synthesis is strongly correlated with the representation of several microbes in high-fat diet-fed mice, while there were almost no correlations in db/db mice. Therefore, the degree of obesity and the composition of the correspondent microbiota are the main contributors to the representation of genes and pathways for cobalamin biosynthesis in the mouse gut.

Decreased vitamin D bio-availability with altered DNA methylation of its metabolism genes in association with the metabolic disorders among the school-aged children with degree I, II, and III obesity

Obesity is strongly associated with disturbances of vitamin D (VD) metabolites in the animal models. However, the related epidemiological evidence is still controversial, especially the different degrees of obesity children. Hence, in this present representative case-control study, 106 obesity school-age children aged 7-12 years were included and divided into different subgroups as degree I (the age- and sex-specific BMI≥95th percentile, n=45), II (BMI ≥120% percentile, n=34) and III (BMI ≥140% percentile, n=27) obesity groups across the ranges of body mass index (BMI). While the age- and sex-matched subjects without obesity were as the control group. Notably, it was significantly different of body composition, anthropological and clinical characteristics among the above four subgroups with the dose-response relationships (P<.05). Moreover, comparing with the control group, the serum VD concentrations were higher, VD metabolites like 25(OH)D, 25(OH)D3 and 1,25(OH)2D, and related hydroxylases as CYP27A1, CYP2R1 and CYP27B1 were lower in the degree I, II, and III obesity subgroups (P<.05), which were more disorder with the anthropological and clinical characteristics as the obesity was worsen in a BMI-independent manner (P<.05). However, there was a significant increase of CYP27B1 in the degree III obesity group than those in the degree I and II obesity subgroups. Furthermore, the methylation patterns on the genome-wide (Methylation/Hydroxymethylation) and VD metabolism genes (CYP27A1, CYP2R1 and CYP27B1) were negatively correlated with the worse obesity and their related expressions (P<.05). In summary, these results indicated that obesity could affect the homeostasis of VD metabolism related genes such as CYP27A1, CYP2R1, CYP27B1 and etc through abnormal DNA methylation, resulting in the disorders of VD related metabolites to decrease VD bio-availability with the BMI-independent manner. In turn, the lower levels of VD metabolites would affect the liver function to exacerbate the progression of obesity, as the Degree II and III obesity subgroups.

The science of micronutrients in clinical practice - Report on the ESPEN symposium

BACKGROUND & AIMS

The European Society for Clinical Nutrition and Metabolism published its first clinical guidelines for use of micronutrients (MNs) in 2022. A two-day web symposium was organized in November 2022 discussing how to apply the guidelines in clinical practice. The present paper reports the main findings of this symposium.

METHODS

Current evidence was discussed, the first day being devoted to clarifying the biology underlying the guidelines, especially regarding the definition of deficiency, the impact of inflammation, and the roles in antioxidant defences and immunity. The second day focused on clinical situations with high prevalence of MN depletion and deficiency.

RESULTS

The importance of the determination of MN status in patients at risk and diagnosis of deficiencies is still insufficiently perceived, considering the essential role of MNs in immune and antioxidant defences. Epidemiological data show that deficiencies of several MNs (iron, iodine, vitamin D) are a global problem that affects human health and well-being including immune responses such as to vaccination. Clinical conditions frequently associated with MN deficiencies were discussed including cancer, obesity with impact of bariatric surgery, diseases of the gastrointestinal tract, critical illness, and aging. In all these conditions, MN deficiency is associated with worsening of outcomes. The recurrent problem of shortage of MN products, but also lack of individual MN-products is a worldwide problem.

CONCLUSION

Despite important progress in epidemiology and clinical nutrition, numerous gaps in practice persist. MN depletion and deficiency are frequently insufficiently searched for in clinical conditions, leading to inadequate treatment. The symposium concluded that more research and continued education are required to improve patient outcome.

Effects of antibiotic, acidifier, and probiotic supplementation on mortality rates, lipoprotein profile, and carcass traits of broiler chickens

Antimicrobial resistance is a significant issue, therefore it's relevant to assess the effects of antibiotics, acidifiers, and probiotic supplementation finding a good alternative to reduce the use of antibiotics in broiler production in rural areas of Bangladesh. Using randomized control trial, this 28-day study evaluated 360 Hubbard Classic broiler chicks divided into four groups: oxytetracycline-treated, acidifier-treated, Lactobacillus-based probiotic-treated, and control (no antibiotics, acidifiers, or probiotics). Each group was replicated three times with 30 birds each with adlibitum feeding. Body weight and feed intake were recorded weekly, and on 28th day, carcass traits and blood lipoprotein levels were evaluated. Results showed that in first and fourth weeks, the body weight gain significantly varied in probiotics and acidifier-treated birds than the control group (P < 0.001). The probiotic group had gained considerable increase in body weight (185.0 g vs 161.7 g and 1745.0 g vs 1592.7 g) than the control group. Notably, in the first week, the feed conversion ratio for the probiotic group was 0.76, but the antibiotic group's was 0.96 (P < 0.001). The weights of the drumstick (88.33 g) and liver (61.0 g) having probiotic supplements were substantially higher than those in the control group (77.0 g and 51.33 g, respectively) (P < 0.001). According to serum lipoprotein analysis, the probiotic and acidifier groups exhibited lower LDL levels (71.1 mg/dl and 69.8 mg/dl, respectively) and higher triglyceride levels (122.9 mg/dl and 135.4 mg/dl). These findings highlight the potential of probiotics and acidifiers as effective antibiotic alternatives, promoting carcass traits and lowering LDL levels in broilers in Bangladesh.

Comparative genomics reveals extensive intra-species genetic divergence of the prevalent gut commensal Ruminococcus gnavus

Ruminococcus gnavus is prevalent in the intestines of humans and animals, and ambiguities have been reported regarding its relations with the development of diseases and host well-being. We postulate the ambiguities of its function in different cases may be attributed to strain-level variability of genomic features of R. gnavus. We performed comparative genomic and pathogenicity prediction analysis on 152 filtered high-quality genomes, including 4 genomes of strains isolated from healthy adults in this study. The mean G+C content of genomes of R. gnavus was 42.73±0.33 mol%, and the mean genome size was 3.46±0.34 Mbp. Genome-wide evolutionary analysis revealed R. gnavus genomes were divided into three major phylogenetic clusters. Pan-core genome analysis revealed that there was a total of 28 072 predicted genes, and the core genes, soft-core genes, shell genes and cloud genes accounted for 3.74 % (1051/28 072), 1.75 % (491/28 072), 9.88 % (2774/28 072) and 84.63 % (23 756/28 072) of the total genes, respectively. The small proportion of core genes reflected the wide divergence among R. gnavus strains. We found certain coding sequences with determined health benefits (such as vitamin production and arsenic detoxification), whilst some had an implication of health adversity (such as sulfide dehydrogenase subunits). The functions of the majority of core genes were unknown. The most widespread genes functioning in antibiotic resistance and virulence are tetO (tetracycline-resistance gene, present in 75 strains) and cps4J (capsular polysaccharide biosynthesis protein Cps4J encoding gene, detected in 3 genomes), respectively. Our results revealed genomic divergence and the existence of certain safety-relevant factors of R. gnavus. This study provides new insights for understanding the genomic features and health relevance of R. gnavus, and raises concerns regarding predicted prevalent pathogenicity and antibiotic resistance among most of the strains.

Functional Foods: A Promising Strategy for Restoring Gut Microbiota Diversity Impacted by SARS-CoV-2 Variants

Natural herbs and functional foods contain bioactive molecules capable of augmenting the immune system and mediating anti-viral functions. Functional foods, such as prebiotics, probiotics, and dietary fibers, have been shown to have positive effects on gut microbiota diversity and immune function. The use of functional foods has been linked to enhanced immunity, regeneration, improved cognitive function, maintenance of gut microbiota, and significant improvement in overall health. The gut microbiota plays a critical role in maintaining overall health and immune function, and disruptions to its balance have been linked to various health problems. SARS-CoV-2 infection has been shown to affect gut microbiota diversity, and the emergence of variants poses new challenges to combat the virus. SARS-CoV-2 recognizes and infects human cells through ACE2 receptors prevalent in lung and gut epithelial cells. Humans are prone to SARS-CoV-2 infection because their respiratory and gastrointestinal tracts are rich in microbial diversity and contain high levels of ACE2 and TMPRSS2. This review article explores the potential use of functional foods in mitigating the impact of SARS-CoV-2 variants on gut microbiota diversity, and the potential use of functional foods as a strategy to combat these effects.

The human microbial exposome: expanding the Exposome-Explorer database with gut microbial metabolites

Metabolites produced by the gut microbiota play an important role in the cross-talk with the human host. Many microbial metabolites are biologically active and can pass the gut barrier and make it into the systemic circulation, where they form the gut microbial exposome, i.e. the totality of gut microbial metabolites in body fluids or tissues of the host. A major difficulty faced when studying the microbial exposome and its role in health and diseases is to differentiate metabolites solely or partially derived from microbial metabolism from those produced by the host or coming from the diet. Our objective was to collect data from the scientific literature and build a database on gut microbial metabolites and on evidence of their microbial origin. Three types of evidence on the microbial origin of the gut microbial exposome were defined: (1) metabolites are produced in vitro by human faecal bacteria; (2) metabolites show reduced concentrations in humans or experimental animals upon treatment with antibiotics; (3) metabolites show reduced concentrations in germ-free animals when compared with conventional animals. Data was manually collected from peer-reviewed publications and inserted in the Exposome-Explorer database. Furthermore, to explore the chemical space of the microbial exposome and predict metabolites uniquely formed by the microbiota, genome-scale metabolic models (GSMMs) of gut bacterial strains and humans were compared. A total of 1848 records on one or more types of evidence on the gut microbial origin of 457 metabolites was collected in Exposome-Explorer. Data on their known precursors and concentrations in human blood, urine and faeces was also collected. About 66% of the predicted gut microbial metabolites (n = 1543) were found to be unique microbial metabolites not found in the human GSMM, neither in the list of 457 metabolites curated in Exposome-Explorer, and can be targets for new experimental studies. This new data on the gut microbial exposome, freely available in Exposome-Explorer ( http://exposome-explorer.iarc.fr/ ), will help researchers to identify poorly studied microbial metabolites to be considered in future studies on the gut microbiota, and study their functionalities and role in health and diseases.

Vitamin D, Gut Microbiota, and Cardiometabolic Diseases-A Possible Three-Way Axis

Metabolic syndrome (MetSyn) is a precursor for several cardiometabolic diseases such as obesity, type-2 diabetes mellitus (T2DM), and cardiovascular diseases. Emerging evidence suggests that vitamin D deficiency links to cardiometabolic diseases through microbiota. A combination of poor vitamin D status and dysbiosis may contribute to the progression of cardiometabolic diseases. Therefore, in this review, we present the relationship among vitamin D, microbiota, and cardiometabolic diseases with a focus on MetSyn. We searched major databases for reports on vitamin D, microbiota, and MetSyn until June 2022. We reviewed 13 reports on the relation between vitamin D and MetSyn (6 randomized controlled and 7 cross-sectional studies) and 6 reports on the effect of vitamin D on the gut microbiome. Adequate vitamin D status has a beneficial effect on gut microbiota, therefore preventing the progression of MetSyn. Further, well-controlled studies are needed for a better understanding of the mechanisms of action involving vitamin D and microbiota in the pathogenesis of cardiometabolic diseases.

Vitamin B12 Status and Gut Microbiota among Saudi Females with Obesity

Previous studies have suggested that dietary habits and dysbiosis of gut microbiota contributed to obesity development. Vitamin B12 is produced by microbes; however, the relationships between vitamin B12, gut microbiome, and obesity are understudied. We aimed to determine the association between vitamin B12 status and gut microbiota relative to obesity in 92 Saudi Arabian females aged 19-25 years who were obese (n = 44) or normal weight (n = 48). Anthropometric, biochemical data, and dietary data were collected. The microbial communities of stool samples were characterized using the shotgun metagenomic sequencing technique. The relationship between vitamin B12 status and gut microbiota composition was identified using Pearson correlation analysis. A statistically significant difference was found in bacterial α- and β-diversity between the groups relative to median serum vitamin B12 level (404.0 pg/mL) and body weight. In the total participants, dietary vitamin B12 intake was inversely correlated with Bifidobacterium kashiwanohense and Blautia wexlerae species. In obese participants, dietary vitamin B12 intake was inversely correlated with Akkermansia muciniphila species and species from the Verrucomicrobia phylum, whereas it was positively correlated with Bacteroides species. Our findings indicate that the abundance (frequency) and diversity (richness) of gut microbiota are associated with vitamin B12 levels and obesity in young females.

Interplay between dietary intake, gut microbiota, and metabolic profile in obese adolescents: Sex-dependent differential patterns

BACKGROUND & AIMS

The interplay among dietary intake, gut microbiota, gut metabolites and circulating metabolites in adolescents is barely known, not to mention sex-dependent pattern. We aimed to explore unique profiles of gut bacterial, gut metabolites and circulating metabolites from both genders of adolescents due to BMI and eating pattern.

METHODS

Clinical indices, fecal gut microbiota, fecal and plasma metabolites, and diet intake information were collected in case-control sample matched for normal and obesity in girls (normal = 12, obesity = 12) and boys (normal = 20, obesity = 20), respectively. 16S rRNA gene sequencing and untargeted metabolomics was performed to analysis the signature of gut microbiota and metabolites. Unique profiles of girls associated with BMI and eating pattern was revealed by Spearman's correlations analysis, co-occurrence network analysis, Kruskal-Wallis test, and Wilcoxon rank-sum test.

RESULTS

Gender difference was found between normal and obese adolescents in gut microbiota, fecal metabolites, and plasma metabolites. The Parabacteroides were only decreased in obese girls. And the characteristic of obese girls' and boys' cases in fecal and plasma was xanthine and glutamine, ornithine and LCA, respectively. Soy products intake was negatively associated with Parabacteroides. The predicted model has a higher accuracy based on the combined markers in obesity boys (AUC = 0.97) and girls (AUC = 0.97), respectively.

CONCLUSIONS

Reduced abundance of Phascolarctobacterium and Parabacteroides, as well as the increased fecal xanthine and ornithine, may provide a novel biomarker signature in obesity girls and boys. Soy products intake was positively and negatively associated with Romboutsia and Parabacteroides abundance, respectively. And the combined markers facilitate the accuracy of predicting obesity in girls and boys in advance.

Influence of biotin intervention on glycemic control and lipid profile in patients with type 2 diabetes mellitus: A systematic review and meta-analysis

Background

Biotin is a water-soluble vitamin acting as a covalently bound coenzyme in regulating energy production. Previous studies have reported that biotin supplementation may influence blood glucose and lipid level in patients with type 2 diabetes mellitus (T2DM).

Methods

We searched Pubmed, Embase, and Cochrane library databases up to 8th August 2022 for studies examining the effects of biotin supplementation in T2DM patients. Pooled effects were measured by weighted mean differences (WMDs) with 95% confidence intervals (CI) using random effects models. Inter-study heterogeneity was assessed and quantified.

Results

A total of five random controlled trials (RCT), involving 445 participants were included. It was suggested that biotin supplementation for 28 to 90 days significantly decreased the level of fasting blood glucose (FBG) (MD: -1.21 mmol/L, 95% CI: -2.73 to 0.31), total cholesterol (TC) (MD: -0.22 mmol/L, 95% CI: -0.25 to -0.19) and triglycerides (TG) (MD: -0.59 mmol/L, 95% CI: -1.21 to 0.03). No significant beneficial effects were observed on insulin (MD: 1.88 pmol/L 95% CI: -13.44 to 17.21). Evidence for the impact of biotin supplementation on the levels of glycated hemoglobin (HbA1c), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and very low-density lipoprotein cholesterol (VLDL-C) was limited to draw conclusion.

Conclusions

Biotin supplementation may decrease FBG, TC and TG levels. However, its influence on insulin is not significant and further studies on the effects of biotin on HbA1c, LDL-C, HDL-C and VLDL-C are expected.

Discovering Biomarkers for Non-Alcoholic Steatohepatitis Patients with and without Hepatocellular Carcinoma Using Fecal Metaproteomics

High-calorie diets lead to hepatic steatosis and to the development of non-alcoholic fatty liver disease (NAFLD), which can evolve over many years into the inflammatory form of non-alcoholic steatohepatitis (NASH), posing a risk for the development of hepatocellular carcinoma (HCC). Due to diet and liver alteration, the axis between liver and gut is disturbed, resulting in gut microbiome alterations. Consequently, detecting these gut microbiome alterations represents a promising strategy for early NASH and HCC detection. We analyzed medical parameters and the fecal metaproteome of 19 healthy controls, 32 NASH patients, and 29 HCC patients, targeting the discovery of diagnostic biomarkers. Here, NASH and HCC resulted in increased inflammation status and shifts within the composition of the gut microbiome. An increased abundance of kielin/chordin, E3 ubiquitin ligase, and nucleophosmin 1 represented valuable fecal biomarkers, indicating disease-related changes in the liver. Although a single biomarker failed to separate NASH and HCC, machine learning-based classification algorithms provided an 86% accuracy in distinguishing between controls, NASH, and HCC. Fecal metaproteomics enables early detection of NASH and HCC by providing single biomarkers and machine learning-based metaprotein panels.

Synbiotic Supplements in the Prevention of Obesity and Obesity-Related Diseases

Obesity and being overweight have reached incredible proportions worldwide and are one of the most common human health problems. The causes of obesity are multifactorial, including a complex interplay among genes, metabolism, diet, physical activity, and the environment. The intestinal microbiota has the ability to affect the host physiology for both benefit and damage, either directly or through microbial metabolites. The aim of this review is to discuss the mechanisms by which the intestinal microbiota could act as a key modifier of obesity and related metabolic abnormalities. The synbiotic components provide an optimal target for modulation of the intestinal microbiota and help reshape the metabolic profile in obese people. The development of novel functional foods containing synbiotic ingredients may present a support in the prevention of obesity as one of the risk factors for chronic diseases. Knowledge of the synbiotic mechanisms of action and the use of new functional foods supplemented with probiotics and prebiotics will facilitate the clinical application and development of individual health care strategies.

Polydextrose Alleviates Adipose Tissue Inflammation and Modulates the Gut Microbiota in High-Fat Diet-Fed Mice

The soluble dietary fiber polydextrose (PDX) is a randomly linked glucose oligomer containing small amounts of sorbitol and citric acid and is widely used in the food industry. However, whether PDX can prevent and treat obesity in high-fat diet (HFD)-fed mice has not been directly investigated, and further studies are needed to better understand the complex interactions among PDX, adipose tissue inflammation and the gut microbiota. In the present study, PDX reduced body weight, fasting blood glucose (FBG), adipose tissue accumulation, adipocyte hypertrophy, serum total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) levels in HFD-fed mice. Moreover, PDX alleviated serum lipopolysaccharide (LPS) levels and macrophage infiltration in epididymal adipose tissue and resulted in macrophage polarization toward the M2 phenotype. Gut microbiota analysis revealed that PDX promoted the growth of beneficial microbes such as Bacteroides, Parabacteroides, Alloprevotella, Muribaculum, Akkermansia, Ruminococcaceae_UCG-014 and UBA1819 in obese mice, which were negatively correlated with subcutaneous fat, epididymal fat, body weight, FBG, serum TC, HDL-C, LDL-C and LPS levels. Our results indicates that PDX can prevent and treat obesity in HFD-fed mice, specifically in alleviating glucolipid metabolism disorders and adipose tissue inflammation, which may be mediated by modulating the structure of the gut microbiota. Therefore, PDX may become a promising nondrug therapy for obesity.