Body size phenotypes comprehensively assess cardiometabolic risk and refine the association between obesity and gut microbiota

Polyphenols Influence the Development of Endometrial Cancer by Modulating the Gut Microbiota

Dysbiosis of the microbiota in the gastrointestinal tract can induce the development of gynaecological tumours, particularly in postmenopausal women, by causing DNA damage and alterations in metabolite metabolism. Dysbiosis also complicates cancer treatment by influencing the body's immune response and disrupting the sensitivity to chemotherapy drugs. Therefore, it is crucial to maintain homeostasis in the gut microbiota through the effective use of food components that affect its structure. Recent studies have shown that polyphenols, which are likely to be the most important secondary metabolites produced by plants, exhibit prebiotic properties. They affect the structure of the gut microbiota and the synthesis of metabolites. In this review, we summarise the current state of knowledge, focusing on the impact of polyphenols on the development of gynaecological tumours, particularly endometrial cancer, and emphasising that polyphenol consumption leads to beneficial modifications in the structure of the gut microbiota.

Obesity is the main driver of altered gut microbiome functions in the metabolically unhealthy

Obesity (OB) and cardiometabolic disease are major public health issues linked to changes in the gut microbiome. OB and poor cardiometabolic health status (CHS) are often comorbid, which hinders efforts to identify components of the microbiome uniquely linked to either one. Here, we used a deeply phenotyped cohort of 408 adults from Colombia, including subjects with OB, unhealthy CHS, or both, to validate previously reported features of gut microbiome function and diversity independently correlated with OB or CHS using fecal metagenomes. OB was defined by body mass index, waist circumference, and body fat; CHS as healthy or unhealthy according to blood biochemistry and anthropometric data. We found that OB, more so than metabolic status, drove associations with gut microbiome structure and functions. The microbiome of obese individuals with and without co-existing unhealthy CHS was characterized by reduced metagenomic diversity, reduced fermentative potential and elevated capacity to respond to oxidative stress and produce bacterial antigens. Disease-linked features were correlated with increased host blood pressure and inflammatory markers, and were mainly contributed by members of the family Enterobacteriaceae. Our results link OB with a microbiome able to tolerate an inflammatory and oxygenated gut state, and suggest that OB is the main driver of microbiome functional differences when poor CHS is a comorbidity.

Gut microbial change after administration of Lacticaseibacillus paracasei AO356 is associated with anti-obesity in a mouse model

Introduction

The status of an impaired gut microbial community, known as dysbiosis, is associated with metabolic diseases such as obesity and insulin resistance. The use of probiotics has been considered an effective approach for the treatment and prevention of obesity and related gut microbial dysbiosis. The anti-obesity effect of Lacticaseibacillus paracasei AO356 was recently reported. However, the effect of L. paracasei AO356 on the gut microbiota has not yet been identified. This study aimed to elucidate the effect of L. paracasei AO356 on gut microbiota and ensure its safety for use as a probiotic.

Methods

Oral administration of L. paracasei AO356 (107 colony-forming units [CFU]/mg per day, 5 days a week, for 10 weeks) to mice fed a high-fat diet significantly suppressed weight gain and fat mass. We investigated the composition of gut microbiota and explored its association with obesity-related markers.

Results

Oral administration of L. paracasei AO356 significantly changed the gut microbiota and modified the relative abundance of Lactobacillus, Bacteroides, and Oscillospira. Bacteroides and Oscillospira were significantly related to the lipid metabolism pathway and obesity-related markers. We also confirmed the safety of L. paracasei AO356 using antibiotics resistance, hemolysis activity, bile salt hydrolase activity, lactate production, and toxicity tests following the safety assessment guidelines of the Ministry of Food and Drug Safety (MFDS).

Discussion

This study demonstrated that L. paracasei AO356 is not only associated with an anti-obesity effect but also with changes in the gut microbiota and metabolic pathways related to obesity. Furthermore, the overall safety assessment seen in this study could increase the potential use of new probiotic materials with anti-obesity effects.

The Vaginal Microbiota of Pregnant Women Varies with Gestational Age, Maternal Age, and Parity

The composition of the vaginal microbiota is heavily influenced by pregnancy and may factor into pregnancy complications, including spontaneous preterm birth. However, results among studies have been inconsistent due, in part, to variation in sample sizes and ethnicity. Thus, an association between the vaginal microbiota and preterm labor continues to be debated. Yet, before assessing associations between the composition of the vaginal microbiota and preterm labor, a robust and in-depth characterization of the vaginal microbiota throughout pregnancy in the specific study population under investigation is required. Here, we report a large longitudinal study (n = 474 women, 1,862 vaginal samples) of a predominantly African-American cohort-a population that experiences a relatively high rate of pregnancy complications-evaluating associations between individual identity, gestational age, and other maternal characteristics with the composition of the vaginal microbiota throughout gestation resulting in term delivery. The principal factors influencing the composition of the vaginal microbiota in pregnancy are individual identity and gestational age at sampling. Other factors are maternal age, parity, obesity, and self-reported Cannabis use. The general pattern across gestation is for the vaginal microbiota to remain or transition to a state of Lactobacillus dominance. This pattern can be modified by maternal parity and obesity. Regardless, network analyses reveal dynamic associations among specific bacterial taxa within the vaginal ecosystem, which shift throughout the course of pregnancy. This study provides a robust foundational understanding of the vaginal microbiota in pregnancy and sets the stage for further investigation of this microbiota in obstetrical disease. IMPORTANCE There is debate regarding links between the vaginal microbiota and pregnancy complications, especially spontaneous preterm birth. Inconsistencies in results among studies are likely due to differences in sample sizes and cohort ethnicity. Ethnicity is a complicating factor because, although all bacterial taxa commonly inhabiting the vagina are present among all ethnicities, the frequencies of these taxa vary among ethnicities. Therefore, an in-depth characterization of the vaginal microbiota throughout pregnancy in the specific study population under investigation is required prior to evaluating associations between the vaginal microbiota and obstetrical disease. This initial investigation is a large longitudinal study of the vaginal microbiota throughout gestation resulting in a term delivery in a predominantly African-American cohort, a population that experiences disproportionally negative maternal-fetal health outcomes. It establishes the magnitude of associations between maternal characteristics, such as age, parity, body mass index, and self-reported Cannabis use, on the vaginal microbiota in pregnancy.

Effect of a Multispecies Synbiotic Supplementation on Body Composition, Antioxidant Status, and Gut Microbiomes in Overweight and Obese Subjects: A Randomized, Double-Blind, Placebo-Controlled Study

Studies investigating the effect of multispecies synbiotic supplementation in obesity management are limited. The current study was performed to evaluate the effects of multispecies probiotics mixed with fructooligosaccharides on body composition, antioxidant status, and gut microbiome composition in overweight and obese individuals. We employed a randomized, double-blind, placebo-controlled trial design, in which 63 individuals aged 18-45 years were assigned to receive either a synbiotic supplement or placebo for 12 weeks. The synbiotic group consumed a daily dose of 37 × 10⁹ colony-forming units (CFU) of a unique blend of seven different probiotics, along with 2 g of fructooligosaccharides, while the placebo group consumed 2 g of maltodextrin daily. Assessments were performed at baseline, week 6, and the end of the study. The results of the study indicated that synbiotic supplementation resulted in a significant reduction in waist circumference and body fat percentage compared to the baseline measurements, as observed at 12 weeks. At the end of the study, there were no significant differences observed in body weight, BMI, waist circumference, or percentage of body fat between the synbiotic group and the placebo group. An analysis of plasma antioxidant capacity revealed that synbiotic supplementation caused a significant increase in Trolox equivalent antioxidant capacity (TEAC) and a concomitant decrease in malondialdehyde (MDA) in the test group when compared to the placebo. For the gut microbiota analysis, synbiotic supplementation significantly decreased Firmicutes abundance and the Firmicutes/Bacteroidetes (F/B) ratio at week 12 as compared to the placebo group. Nevertheless, the synbiotic group did not exhibit any substantial alterations in other biochemical blood parameters compared to the placebo group. These findings suggest that multispecies synbiotic supplementation could be a beneficial strategy to improve body composition, antioxidant status, and gut microbiome composition in overweight and obese subjects.

Putative intestinal permeability markers do not correlate with cardiometabolic health and gut microbiota in humans, except for peptides recognized by a widely used zonulin ELISA kit

BACKGROUND AND AIMS

Cardiometabolic diseases refer to a group of interrelated conditions, sharing metabolic dysfunctions like insulin resistance, obesity, dyslipidemia, and hypertension. The gut microbiota has been associated with CMD and related conditions. Alterations in the intestinal epithelium permeability triggered by chronic stress and diet could bridge gut microbiota with inflammation and CMD development. Here, we assessed the relationship between intestinal permeability and circulating SCFAs with cardiometabolic health status (CMHS) and gut microbiota in a sample of 116 Colombian adults.

METHODS AND RESULTS

Plasma levels of lipopolysaccharide-binding protein (LBP), intestinal fatty acid-binding protein (I-FABP), claudin-3, and purported zonulin peptides (PZP) were measured by ELISA, whereas plasmatic levels of acetate, propionate, butyrate, isobutyrate, and valerate were measured by gas chromatography/mass spectrometry. In addition, for further statistical analysis, we took data previously published by us on this cohort, including gut microbiota and multiple CMD risk factors that served to categorize subjects as cardiometabolically healthy or cardiometabolically abnormal. From univariate and multivariate statistical analyses, we found the levels of I-FABP, LBP, and PZP increased in the plasma of cardiometabolically abnormal individuals, although only PZP reached statistical significance.

CONCLUSIONS

Our results did not confirm the applicability of I-FABP, LBP, claudin-3, or SCFAs as biomarkers for associating intestinal permeability with the cardiometabolic health status in these subjects. On the other hand, the poorly characterized peptides detected with the ELISA kit branded as "zonulin" were inversely associated with cardiometabolic dysfunctions and gut microbiota. Further studies to confirm the true identity of these peptides are warranted.

Dietary antioxidant intake is inversely associated with 2,3-dinor oxylipin metabolites, the major excreted oxylipins in overweight and obese subjects

Cardiometabolic disease risk factors, including obesity, insulin resistance, high blood pressure, and dyslipidemia, are associated with elevated oxidative stress biomarkers like oxylipins. Increased adiposity by itself induces various isomers of this oxidized lipid family, while dietary polyphenols show benefits in its regulation. Previously, we showed that specific co-abundant microorganisms characterized the gut microbiota of Colombians and associated differentially with diet, lifestyle, obesity, and cardiometabolic health status, which led us to hypothesize that urinary oxylipins would reflect the intensity of oxidative metabolism linked to gut microbiota dysbiosis. Thus, we selected a convenience sample of 105 participants (age: 40.2 ± 11.9 years, 47.6% women), grouped according to microbiota, cardiometabolic health status, and body mass index (BMI); and evaluated 33 urinary oxylipins by HPLC-QqQ-MS/MS (e.g., isoprostanes, prostaglandins, and metabolites), paired with anthropometry and blood chemistry information and dietary antioxidants estimated from a 24-h food recall. In general, oxylipins did not show differences among individuals who differed in gut microbiota. While the unmetabolized oxylipin levels were not associated with BMI, the total content of oxylipin metabolites was highest in obese and cardiometabolically abnormal subjects (e.g., insulin resistant), mainly by prostaglandin-D (2,3-dinor-11β-PGF_2α) and 15-F_2t-IsoPs (2,3-dinor-15-F_2t-IsoP and 2,3-dinor-15-epi-15-F_2t-IsoP) metabolites. The total polyphenol intake in this cohort was 1070 ± 627 mg/day. After adjusting for body weight, the polyphenol intake was significantly higher in lean than overweight and showed an inverse association with dinor-oxylipin levels in principal component analysis. These results suggest that the 2,3-dinor-oxylipins could be more specific biomarkers associated with BMI than their parent oxylipins and that are sensitive to be regulated by dietary antioxidants.

Pleurotus Ostreatus Ameliorates Obesity by Modulating the Gut Microbiota in Obese Mice Induced by High-Fat Diet

Pleurotus ostreatus (PO), a common edible mushroom, contains rich nutritional components with medicinal properties. To explore the effect of PO on ameliorating obesity and modulating the gut microbiota, we administered the mice with a low-fat diet or high-fat diet containing different dosages of PO (mass fraction: 0%, 2.5%, 5% and 10%). The body weight, adipose tissue weight, GTT, ITT, blood lipids, serum biomarkers of liver/kidney function, the gut microbiota and function were measured and analyzed after 6 weeks of PO treatment. The results showed PO prevented obesity, maintained glucose homeostasis and beneficially modulated gut microbiota. PO modified the composition and functions of gut microbiota in obese mice and make them similar to those in lean mice, which contributed to weight loss. PO significantly increased the relative abundance of Oscillospira, Lactobacillus group and Bifidobacterium, while decreased the relative abundance of Bacteroides and Roseburia. The prediction of gut microbiota function showed PO upregulated lipid metabolism, carbohydrate metabolism, bile acid biosynthesis, while it downregulated adipocytokine signaling pathway and steroid hormone biosynthesis. Correlation analysis further suggested the potential relationship among obesity, gut microbiota and the function of gut microbiota. In conclusion, all the results indicated that PO ameliorated obesity at least partly by modulating the gut microbiota.

Consistent Alterations of Human Fecal Microbes After Transplantation into Germ-free Mice

Fecal microbiota transplantation (FMT) of human fecal samples into germ-free (GF) mice is useful for establishing causal relationships between the gut microbiota and human phenotypes. However, due to the intrinsic differences between human and mouse intestines and the different diets of the two organisms, it may not be possible to replicate human phenotypes in mice through FMT; similarly, treatments that are effective in mouse models may not be effective in humans. In this study, we aimed to identify human gut microbes that undergo significant and consistent changes (i.e., in relative abundances) after transplantation into GF mice in multiple experimental settings. We collected 16S rDNA-seq data from four published studies and analyzed the gut microbiota profiles from 1713 human-mouse pairs. Strikingly, on average, we found that only 47% of the human gut microbes could be re-established in mice at the species level, among which more than 1/3 underwent significant changes (referred to as "variable taxa"). Most of the human gut microbes that underwent significant changes were consistent across multiple human-mouse pairs and experimental settings. Consequently, about 1/3 of human samples changed their enterotypes, i.e., significant changes in their leading species after FMT. Mice fed with a controlled diet showed a lower enterotype change rate (23.5%) than those fed with a noncontrolled diet (49.0%), suggesting a possible solution for rescue. Most of the variable taxa have been reported to be implicated in human diseases, with some recognized as the causative species. Our results highlight the challenges of using a mouse model to replicate human gut microbiota-associated phenotypes, provide useful information for researchers using mice in gut microbiota studies, and call for additional validations after FMT. An online database named FMT-DB is publicly available at http://fmt2mice.humangut.info/#/.

Evaluating the effects of a standardized polyphenol mixture extracted from poplar-type propolis on healthy and diseased human gut microbiota

INTRODUCTION

A large body of evidence suggests that propolis exerts antioxidant, anti-inflammatory, and antimicrobial activities, mostly ascribed to its polyphenol content. Growing evidence suggests that propolis could modulate gut microbiota exerting a positive impact on several pathological conditions. The aim of this study was to determine the in vitro impact of a poplar-type propolis extract with a standardized polyphenol content, on the composition and functionality of gut microbiota obtained from fecal material of five different donors (healthy adults, and healthy, obese, celiac, and food allergic children).

METHODS

The standardized polyphenol mixture was submitted to a simulated in vitro digestion-fermentation process, designed to mimic natural digestion in the human oral, gastric, and intestinal chambers. The antioxidant profile of propolis before and after the digestion-fermentation process was determined. 16 S rRNA amplicon next-generation sequencing (NGS) was used to test the effects on the gut microbiota of propolis extract. The profile of the short-chain fatty acids (SCFA) produced by the microbiota was also investigated through a chromatographic method coupled with UV detection.

RESULTS

In vitro digestion and fermentation induced a decrease in the antioxidant profile of propolis (i.e., decrease of total polyphenol content, antiradical and reducing activities). Propolis fermentation exhibited a modulatory effect on gut microbiota composition and functionality of healthy and diseased subjects increasing the concentration of SCFA.

CONCLUSIONS

Overall, these data suggest that propolis might contribute to gut health and could be a candidate for further studies in view of its use as a prebiotic ingredient.

Gut microbiota in patients with obesity and metabolic disorders - a systematic review

BACKGROUND

Previous observational studies have demonstrated inconsistent and inconclusive results of changes in the intestinal microbiota in patients with obesity and metabolic disorders. We performed a systematic review to explore evidence for this association across different geography and populations.

METHODS

We performed a systematic search of MEDLINE (OvidSP) and Embase (OvidSP) of articles published from Sept 1, 2010, to July 10, 2021, for case-control studies comparing intestinal microbiome of individuals with obesity and metabolic disorders with the microbiome of non-obese, metabolically healthy individuals (controls). The primary outcome was bacterial taxonomic changes in patients with obesity and metabolic disorders as compared to controls. Taxa were defined as "lean-associated" if they were depleted in patients with obesity and metabolic disorders or negatively associated with abnormal metabolic parameters. Taxa were defined as "obesity-associated" if they were enriched in patients with obesity and metabolic disorders or positively associated with abnormal metabolic parameters.

RESULTS

Among 2390 reports screened, we identified 110 full-text articles and 60 studies were included. Proteobacteria was the most consistently reported obesity-associated phylum. Thirteen, nine, and ten studies, respectively, reported Faecalibacterium, Akkermansia, and Alistipes as lean-associated genera. Prevotella and Ruminococcus were obesity-associated genera in studies from the West but lean-associated in the East. Roseburia and Bifidobacterium were lean-associated genera only in the East, whereas Lactobacillus was an obesity-associated genus in the West.

CONCLUSIONS

We identified specific bacteria associated with obesity and metabolic disorders in western and eastern populations. Mechanistic studies are required to determine whether these microbes are a cause or product of obesity and metabolic disorders.

Akkermansia muciniphila: is it the Holy Grail for ameliorating metabolic diseases?

The increasing prevalence of metabolic diseases has become a severe public health problem. Gut microbiota play important roles in maintaining human health by modulating the host's metabolism. Recent evidences demonstrate that Akkermansia muciniphila is effective in improving metabolic disorders and is thus considered as a promising "next-generation beneficial microbe". In addition to the live A. muciniphila, similar or even stronger beneficial effects have been observed in pasteurized A. muciniphila and its components, including the outer membrane protein Amuc_1100, A. muciniphila-derived extracellular vesicles (AmEVs), and secreted protein P9. Hence, this paper presents a systemic review of recent progress in the effects and mechanisms of A. muciniphila and its components in the treatment of metabolic diseases, including obesity, type 2 diabetes mellitus, cardiovascular disease, and nonalcoholic fatty liver disease, as well as perspectives on its future study.

Gut Microbiome Composition in Obese and Non-Obese Persons: A Systematic Review and Meta-Analysis

Whether the gut microbiome in obesity is characterized by lower diversity and altered composition at the phylum or genus level may be more accurately investigated using high-throughput sequencing technologies. We conducted a systematic review in PubMed and Embase including 32 cross-sectional studies assessing the gut microbiome composition by high-throughput sequencing in obese and non-obese adults. A significantly lower alpha diversity (Shannon index) in obese versus non-obese adults was observed in nine out of 22 studies, and meta-analysis of seven studies revealed a non-significant mean difference (−0.06, 95% CI −0.24, 0.12, I² = 81%). At the phylum level, significantly more Firmicutes and fewer Bacteroidetes in obese versus non-obese adults were observed in six out of seventeen, and in four out of eighteen studies, respectively. Meta-analyses of six studies revealed significantly higher Firmicutes (5.50, 95% 0.27, 10.73, I² = 81%) and non-significantly lower Bacteroidetes (−4.79, 95% CI −10.77, 1.20, I² = 86%). At the genus level, lower relative proportions of Bifidobacterium and Eggerthella and higher Acidaminococcus, Anaerococcus, Catenibacterium, Dialister, Dorea, Escherichia-Shigella, Eubacterium, Fusobacterium, Megasphera, Prevotella, Roseburia, Streptococcus, and Sutterella were found in obese versus non-obese adults. Although a proportion of studies found lower diversity and differences in gut microbiome composition in obese versus non-obese adults, the observed heterogeneity across studies precludes clear answers.

Cardiometabolic Benefits of Intermittent Fasting

This review aims to summarize the effects of intermittent fasting on markers of cardiometabolic health in humans. All forms of fasting reviewed here-alternate-day fasting (ADF), the 5:2 diet, and time-restricted eating (TRE)-produced mild to moderate weight loss (1-8% from baseline) and consistent reductions in energy intake (10-30% from baseline). These regimens may benefit cardiometabolic health by decreasing blood pressure, insulin resistance, and oxidative stress. Low-density lipoprotein cholesterol and triglyceride levels are also lowered, but findings are variable. Other health benefits, such as improved appetite regulation and favorable changes in the diversity of the gut microbiome, have also been demonstrated, but evidence for these effects is limited. Intermittent fasting is generally safe and does not result in energy level disturbances or increased disordered eating behaviors. In summary, intermittent fasting is a safe diet therapy that can produce clinically significant weight loss (>5%) and improve several markers of metabolic health in individuals with obesity.

The value of gut microbiota to predict feed efficiency and growth of rabbits under different feeding regimes

Gut microbiota plays an important role in nutrient absorption and could impact rabbit feed efficiency. This study aims at investigating such impact by evaluating the value added by microbial information for predicting individual growth and cage phenotypes related to feed efficiency. The dataset comprised individual average daily gain and cage-average daily feed intake from 425 meat rabbits, in which cecal microbiota was assessed, and their cage mates. Despite microbiota was not measured in all animals, consideration of pedigree relationships with mixed models allowed the study of cage-average traits. The inclusion of microbial information into certain mixed models increased their predictive ability up to 20% and 46% for cage-average feed efficiency and individual growth traits, respectively. These gains were associated with large microbiability estimates and with reductions in the heritability estimates. However, large microbiabililty estimates were also obtained with certain models but without any improvement in their predictive ability. A large proportion of OTUs seems to be responsible for the prediction improvement in growth and feed efficiency traits, although specific OTUs taxonomically assigned to 5 different phyla have a higher weight. Rabbit growth and feed efficiency are influenced by host cecal microbiota, thus considering microbial information in models improves the prediction of these complex phenotypes.

Seasonal Variation in Gut Microbiota Related to Diet in Fejervarya limnocharis

Organisms adapt to environmental fluctuations by varying their morphology and structural, physiological, and biochemical characteristics. Gut microbiome, varying rapidly in response to environmental shifts, has been proposed as a strategy for adapting to the fluctuating environment (e.g., new dietary niches). Here, we explored the adaptive mechanism of frog intestinal microbes in response to environmental changes. We collected 170 Fejervarya limnocharis during different seasons (spring, summer, autumn, and pre-hibernation) to study the compositional and functional divergence of gut microbiota and analysed the effects of seasonal feeding habits and body condition on intestinal microorganisms using 16S rRNA high-throughput sequencing, Tax4Fun function prediction analysis, and bioinformatics analysis. The results showed no significant dietary difference in various seasons and between males and females. However, a significantly positive correlation was detected between dietary diversity and food niche width. Host condition (body size, body mass, and body condition) also revealed seasonal changes. The frogs were colonised by 71 bacterial phyla and dominated by Proteobacteria, Firmicutes, and Bacteroidetes. Stenotrophomonas was the most abundant genus in the Proteobacteria. The composition, diversity, and function of intestinal microorganisms in different seasons were significantly different. Significant differences were observed in composition and function but not in the microbial diversity between sexes. Furthermore, seasonal foods and body mass were significantly correlated with gut microbial composition. Our results suggest that gut microbiomes of F. limnocharis vary seasonally in response to diet under fluctuating environments.

Chronic oral exposure to pesticides and their consequences on metabolic regulation: role of the microbiota

Pesticides have long been used in agriculture and household treatments. Pesticide residues can be found in biological samples for both the agriculture workers through direct exposure but also to the general population by indirect exposure. There is also evidence of pesticide contamination in utero and trans-generational impacts. Whilst acute exposure to pesticides has long been associated with endocrine perturbations, chronic exposure with low doses also increases the prevalence of metabolic disorders such as obesity or type 2 diabetes. Dysmetabolism is a low-grade inflammation disorder and as such the microbiota plays a role in its etiology. It is therefore important to fully understand the role of microbiota on the genesis of subsequent health effects. The digestive tract and mostly microbiota are the first organs of contact after oral exposure. The objective of this review is thus to better understand mechanisms that link pesticide exposure, dysmetabolism and microbiota. One of the key outcomes on the microbiota is the reduced Bacteroidetes and increased Firmicutes phyla, reflecting both pesticide exposure and risk factors of dysmetabolism. Other bacterial genders and metabolic activities are also involved. As for most pathologies impacting microbiota (including inflammatory disorders), the role of prebiotics can be suggested as a prevention strategy and some preliminary evidence reinforces this axis.

Diet Quality, Food Groups and Nutrients Associated with the Gut Microbiota in a Nonwestern Population

Diet plays an important role in shaping gut microbiota. However, much remains to be learned regarding this association. We analyzed dietary intake and gut microbiota in a community-dwelling cohort of 441 Colombians. Diet quality, intake of food groups and nutrient consumption were paired with microbial diversity and composition using linear regressions, Procrustes analyses and a random-forest machine-learning algorithm. Analyses were adjusted for potential confounders, including the five cities from where the participants originated, sex (male, female), age group (18-40 and 41-62 years), BMI (lean, overweight, obese) and socioeconomic status. Microbial diversity was higher in individuals with increased intake of nutrients obtained from plant-food sources, whereas the intake of food groups and nutrients correlated with microbiota structure. Random-forest regressions identified microbial communities associated with different diet components. Two remarkable results confirmed previous expectations regarding the link between diet and microbiota: communities composed of short-chain fatty acid (SCFA) producers were more prevalent in the microbiota of individuals consuming diets rich in fiber and plant-food sources, such as fruits, vegetables and beans. In contrast, an inflammatory microbiota composed of bile-tolerant and putrefactive microorganisms along with opportunistic pathogens thrived in individuals consuming diets enriched in animal-food sources and of low quality, i.e., enriched in ultraprocessed foods and depleted in dietary fiber. This study expands our understanding of the relationship between dietary intake and gut microbiota. We provide evidence that diet is strongly associated with the gut microbial community and highlight generalizable connections between them.

Gut Microbiota, Probiotics and Psychological States and Behaviors after Bariatric Surgery-A Systematic Review of Their Interrelation

The gastrointestinal (GI) microbiota plays an important role in health and disease, including brain function and behavior. Bariatric surgery (BS) has been reported to result in various changes in the GI microbiota, therefore demanding the investigation of the impact of GI microbiota on treatment success. The goal of this systematic review was to assess the effects of BS on the microbiota composition in humans and other vertebrates, whether probiotics influence postoperative health, and whether microbiota and psychological and behavioral factors interact. A search was conducted using PubMed and Web of Science to find relevant studies with respect to the GI microbiota and probiotics after BS, and later screened for psychological and behavioral parameters. Studies were classified into groups and subgroups to provide a clear overview of the outcomes. Microbiota changes were further assessed for whether they were specific to BS in humans through the comparison to sham operated controls in other vertebrate studies. Changes in alpha diversity appear not to be specific, whereas dissimilarity in overall microbial community structure, and increases in the abundance of the phylum Proteobacteria and Akkermansia spp. within the phylum Verrucomicrobia after surgery were observed in both human and other vertebrates studies and may be specific to BS in humans. Human probiotic studies differed regarding probiotic strains and dosages, however it appeared that probiotic interventions were not superior to a placebo for quality of life scores or weight loss after BS. The relationship between GI microbiota and psychological diseases in this context is unclear due to insufficient available data.

Exercise training modulates the gut microbiota profile and impairs inflammatory signaling pathways in obese children

Childhood obesity has reached epidemic levels and is a serious health concern associated with metabolic syndrome, nonalcoholic fatty liver disease, and gut microbiota alterations. Physical exercise is known to counteract obesity progression and modulate the gut microbiota composition. This study aims to determine the effect of a 12-week strength and endurance combined training program on gut microbiota and inflammation in obese pediatric patients. Thirty-nine obese children were assigned randomly to the control or training group. Anthropometric and biochemical parameters, muscular strength, and inflammatory signaling pathways in mononuclear cells were evaluated. Bacterial composition and functionality were determined by massive sequencing and metabolomic analysis. Exercise reduced plasma glucose levels and increased dynamic strength in the upper and lower extremities compared with the obese control group. Metagenomic analysis revealed a bacterial composition associated with obesity, showing changes at the phylum, class, and genus levels. Exercise counteracted this profile, significantly reducing the Proteobacteria phylum and Gammaproteobacteria class. Moreover, physical activity tended to increase some genera, such as Blautia, Dialister, and Roseburia, leading to a microbiota profile similar to that of healthy children. Metabolomic analysis revealed changes in short-chain fatty acids, branched-chain amino acids, and several sugars in response to exercise, in correlation with a specific microbiota profile. Finally, the training protocol significantly inhibited the activation of the obesity-associated NLRP3 signaling pathway. Our data suggest the existence of an obesity-related deleterious microbiota profile that is positively modified by physical activity intervention. Exercise training could be considered an efficient nonpharmacological therapy, reducing inflammatory signaling pathways induced by obesity in children via microbiota modulation.

Physical fitness regimens could stimulate shifts in gut microbiome composition and metabolism that counteract health risks associated with childhood obesity. This condition can increase the risk of metabolic and cardiovascular disease later in life. Several studies have indicated that disturbances in the microbial populations in the digestive tract may contribute to these diseases. Researchers led by Sonia Sánchez-Campos of the Institute of Biomedicine, León,Spain, recently assessed the impact of exercise and endurance training on microbiome composition in obese children. They determined that these regimens can produce measurable shifts in the gut microbe population, yielding bacterial communities that are more similar to those seen in non-obese children. These shifts were accompanied by alterations in metabolic activity that may help mitigate inflammatory signaling and other processes that fuel obesity-related disease.

The Firmicutes/Bacteroidetes Ratio: A Relevant Marker of Gut Dysbiosis in Obese Patients?

The gut microbiota is emerging as a promising target for the management or prevention of inflammatory and metabolic disorders in humans. Many of the current research efforts are focused on the identification of specific microbial signatures, more particularly for those associated with obesity, type 2 diabetes, and cardiovascular diseases. Some studies have described that the gut microbiota of obese animals and humans exhibits a higher Firmicutes/Bacteroidetes ratio compared with normal-weight individuals, proposing this ratio as an eventual biomarker. Accordingly, the Firmicutes/Bacteroidetes ratio is frequently cited in the scientific literature as a hallmark of obesity. The aim of the present review was to discuss the validity of this potential marker, based on the great amount of contradictory results reported in the literature. Such discrepancies might be explained by the existence of interpretative bias generated by methodological differences in sample processing and DNA sequence analysis, or by the generally poor characterization of the recruited subjects and, more particularly, the lack of consideration of lifestyle-associated factors known to affect microbiota composition and/or diversity. For these reasons, it is currently difficult to associate the Firmicutes/Bacteroidetes ratio with a determined health status and more specifically to consider it as a hallmark of obesity.

Variants in genes of innate immunity, appetite control and energy metabolism are associated with host cardiometabolic health and gut microbiota composition

Identifying the genetic and non-genetic determinants of obesity and related cardiometabolic dysfunctions is cornerstone for their prevention, treatment, and control. While genetic variants contribute to the cardiometabolic syndrome (CMS), non-genetic factors, such as the gut microbiota, also play key roles. Gut microbiota is intimately associated with CMS and its composition is heritable. However, associations between this microbial community and host genetics are understudied. We contribute filling this gap by genotyping 60 variants in 39 genes of three modules involved in CMS risk, measuring cardiometabolic risk factors, and characterizing gut microbiota in a cohort of 441 Colombians. We hypothesized that CMS risk variants were correlated with detrimental levels of clinical parameters and with the abundance of disease-associated microbes. We found several polymorphisms in genes of innate immunity, appetite control, and energy metabolism that were associated with metabolic dysregulation and microbiota composition; the associations between host genetics and cardiometabolic health were independent of the participants' gut microbiota, and those between polymorphisms and gut microbes were independent of the CMS risk. Associations were also independent of the host genetic ancestry, diet and lifestyle. Most microbes explaining genetic-microbiota associations belonged to the families Lachnospiraceae and Ruminococcaceae. Multiple CMS risk alleles were correlated with increased abundance of beneficial microbiota, suggesting that the phenotypic outcome of the evaluated variants might depend upon the genetic background of the studied population and its environmental context. Our results provide additional evidence that the gut microbiota is under the host genetic control and present pathways of host-microbe interactions.

Profile of the gut microbiota of adults with obesity: a systematic review

Recently, relationship between gut microbiota composition and development of obesity has been pointed. However, the gut microbiota composition of individual with obesity is not known yet. Therefore, this systematic review aimed to evaluate differences in profile of gut microbiota between individuals with obesity and individuals with normal weight. A search performed on August 2019 in the databases Pubmed, Scopus, Web of Science, Cochrane library, Lilacs and gray literature using the terms: "microbiota", "microbiome", "obesity", "obesity morbid", and "humans". Studies assessing the gut microbiota composition in adults with obesity and lean were included. Quality assessment was performed by Newcastle-Ottawa Quality Assessment Scale. Of the 12,496 studies, 32 were eligible and included in this review. Individuals with obesity have a greater Firmicutes/Bacteroidetes ratio, Firmicutes, Fusobacteria, Proteobacteria, Mollicutes, Lactobacillus (reuteri), and less Verrucomicrobia (Akkermansia muciniphila), Faecalibacterium (prausnitzii), Bacteroidetes, Methanobrevibacter smithii, Lactobacillus plantarum and paracasei. In addition, some bacteria had positive correlation and others negative correlation with obesity. Individuals with obesity showed profile of gut microbiota different than individual lean. These results may help in advances of the diagnosis and treatment of obesity.

The double burden of malnutrition: aetiological pathways and consequences for health

Malnutrition has historically been researched and addressed within two distinct silos, focusing either on undernutrition, food insecurity, and micronutrient deficiencies, or on overweight, obesity, and dietary excess. However, through rapid global nutrition transition, an increasing proportion of individuals are exposed to different forms of malnutrition during the life course and have the double burden of malnutrition (DBM) directly. Long-lasting effects of malnutrition in early life can be attributed to interconnected biological pathways, involving imbalance of the gut microbiome, inflammation, metabolic dysregulation, and impaired insulin signalling. Life-course exposure to early undernutrition followed by later overweight increases the risk of non-communicable disease, by imposing a high metabolic load on a depleted capacity for homoeostasis, and in women increases the risk of childbirth complications. These life-course trajectories are shaped both by societal driving factors-ie, rapidly changing diets, norms of eating, and physical activity patterns-and by broader ecological factors such as pathogen burden and extrinsic mortality risk. Mitigation of the DBM will require major societal shifts regarding nutrition and public health, to implement comprehensive change that is sustained over decades, and scaled up into the entire global food system.

Alterations in the Gut Microbiome at 6 Months of Age in Obese Latino Infants

Objective: To investigate gut microbial composition in Latino infants in relation to breastfeeding, obesity, and antibiotic exposure.Method: We analyzed the gut microbiome in 6-month-old Latino infants from an ongoing urban mother-child cohort. Alpha and beta diversity were assessed in relation to infants' early dietary exposure and anthropometrics including obesity.Results: Infants exclusively breastfed at 4 to 6 weeks had lower alpha diversity and less bacterial abundance compared with those who did not. Breastfeeding status at 4 to 6 weeks and 6 months of age accounted for differences in alpha and beta diversity. Infants who were obese at 6 months of age had higher levels of alpha diversity compared with non-obese infants.Conclusions: Early exclusive breastfeeding and obesity impacts microbial diversity by 6 months of age in Latino infants, a group at high risk for future obesity.

Oral administration of Lactobacillus fermentum CRL1446 improves biomarkers of metabolic syndrome in mice fed a high-fat diet supplemented with wheat bran

This work evaluated the effect of oral administration of Lactobacillus fermentum CRL1446, feruloyl esterase producing, on metabolic biomarkers and intestinal microbiota of high fat diet-induced metabolic syndrome mice and supplemented with wheat bran.

Gut microbiome composition in the Hispanic Community Health Study/Study of Latinos is shaped by geographic relocation, environmental factors, and obesity

BACKGROUND

Hispanics living in the USA may have unrecognized potential birthplace and lifestyle influences on the gut microbiome. We report a cross-sectional analysis of 1674 participants from four centers of the Hispanic Community Health Study/Study of Latinos (HCHS/SOL), aged 18 to 74 years old at recruitment.

RESULTS

Amplicon sequencing of 16S rRNA gene V4 and fungal ITS1 fragments from self-collected stool samples indicate that the host microbiome is determined by sociodemographic and migration-related variables. Those who relocate from Latin America to the USA at an early age have reductions in Prevotella to Bacteroides ratios that persist across the life course. Shannon index of alpha diversity in fungi and bacteria is low in those who relocate to the USA in early life. In contrast, those who relocate to the USA during adulthood, over 45 years old, have high bacterial and fungal diversity and high Prevotella to Bacteroides ratios, compared to USA-born and childhood arrivals. Low bacterial diversity is associated in turn with obesity. Contrasting with prior studies, our study of the Latino population shows increasing Prevotella to Bacteroides ratio with greater obesity. Taxa within Acidaminococcus, Megasphaera, Ruminococcaceae, Coriobacteriaceae, Clostridiales, Christensenellaceae, YS2 (Cyanobacteria), and Victivallaceae are significantly associated with both obesity and earlier exposure to the USA, while Oscillospira and Anaerotruncus show paradoxical associations with both obesity and late-life introduction to the USA.

CONCLUSIONS

Our analysis of the gut microbiome of Latinos demonstrates unique features that might be responsible for health disparities affecting Hispanics living in the USA.

Sick Individuals and Sick (Microbial) Populations: Challenges in Epidemiology and the Microbiome

The human microbiome represents a new frontier in understanding the biology of human health. While epidemiology in this area is still in its infancy, its scope will likely expand dramatically over the coming years. To rise to the challenge, we argue that epidemiology should capitalize on its population perspective as a critical complement to molecular microbiome research, allowing for the illumination of contextual mechanisms that may vary more across populations rather than among individuals. We first briefly review current research on social context and the gut microbiome, focusing specifically on socioeconomic status (SES) and race/ethnicity. Next, we reflect on the current state of microbiome epidemiology through the lens of one specific area, the association of the gut microbiome and metabolic disorders. We identify key methodological shortcomings of current epidemiological research in this area, including extensive selection bias, the use of noncompositionally robust measures, and a lack of attention to social factors as confounders or effect modifiers.

The human microbiota is associated with cardiometabolic risk across the epidemiologic transition

Oral and fecal microbial biomarkers have previously been associated with cardiometabolic (CM) risk, however, no comprehensive attempt has been made to explore this association in minority populations or across different geographic regions. We characterized gut- and oral-associated microbiota and CM risk in 655 participants of African-origin, aged 25-45, from Ghana, South Africa, Jamaica, and the United States (US). CM risk was classified using the CM risk cut-points for elevated waist circumference, elevated blood pressure and elevated fasted blood glucose, low high-density lipoprotein (HDL), and elevated triglycerides. Gut-associated bacterial alpha diversity negatively correlated with elevated blood pressure and elevated fasted blood glucose. Similarly, gut bacterial beta diversity was also significantly differentiated by waist circumference, blood pressure, triglyceridemia and HDL-cholesterolemia. Notably, differences in inter- and intra-personal gut microbial diversity were geographic-region specific. Participants meeting the cut-points for 3 out of the 5 CM risk factors were significantly more enriched with Lachnospiraceae, and were significantly depleted of Clostridiaceae, Peptostreptococcaceae, and Prevotella. The predicted relative proportions of the genes involved in the pathways for lipopolysaccharides (LPS) and butyrate synthesis were also significantly differentiated by the CM risk phenotype, whereby genes involved in the butyrate synthesis via lysine, glutarate and 4-aminobutyrate/succinate pathways and LPS synthesis pathway were enriched in participants with greater CM risk. Furthermore, inter-individual oral microbiota diversity was also significantly associated with the CM risk factors, and oral-associated Streptococcus, Prevotella, and Veillonella were enriched in participants with 3 out of the 5 CM risk factors. We demonstrate that in a diverse cohort of African-origin adults, CM risk is significantly associated with reduced microbial diversity, and the enrichment of specific bacterial taxa and predicted functional traits in both gut and oral environments. As well as providing new insights into the associations between the gut and oral microbiota and CM risk, this study also highlights the potential for novel therapeutic discoveries which target the oral and gut microbiota in CM risk.

Gut microbiota composition explains more variance in the host cardiometabolic risk than genetic ancestry

Cardiometabolic affections greatly contribute to the global burden of disease. The susceptibility to obesity, cardiovascular disease, and type-2 diabetes, conditions that add to the cardiometabolic syndrome (CMS), was associated with the ancestral genetic composition and gut microbiota. Studies explicitly testing associations between genetic ancestry and gut microbes are growing. We here examined whether the host genetic ancestry was associated with gut microbiota composition, and distinguished the effects of genetic ancestry and non-genetic factors on human cardiometabolic health. We performed a cross-sectional study with 441 community-dwelling Colombian mestizos from five cities spanning the Andes, Pacific, and Caribbean coasts. We characterized the host genetic ancestry by genotyping 40 ancestry informative markers; characterized gut microbiota through 16S rRNA gene sequencing; assessed diet intake, physical activity, cigarette, and medicament consumption; and measured cardiometabolic outcomes that allowed calculating a CMS risk scale. On average, each individual of our cohort was 67 ± 6% European, 21 ± 5% Native American and 12 ± 5% African. Multivariable-adjusted generalized linear models showed that individuals with higher Native American and African ancestries had increased fasting insulin, body mass index and CMS risk, as assessed by the CMS risk scale. Furthermore, we identified 21 OTUs associated to the host genetic ancestry and 20 to cardiometabolic health. While we highlight novel associations between genetic ancestry and gut microbiota, we found that the effect of intestinal microbes was more likely to explain the variance in CMS risk scale than the contributions of European, Native American and African genetic backgrounds.

Altered gut microbiota after traumatic splenectomy is associated with endotoxemia

Splenectomy carries a long-term risk of postoperative infection, and the chronic, low-grade inflammation associated with endotoxemia may be related to the gut microbiota. In this study, to increase our understanding of the potential cause of the high rate of infection in postsplenectomy patients, we evaluated the differences in the gut microbiota and plasma lipopolysaccharide level of patients after splenectomy relative to those of healthy controls. Thirty-two patients having undergone splenectomy and 42 healthy individuals were enrolled into the splenectomy (SP) and healthy control (HC) groups, respectively. The SP group was subdivided into three subgroups according to the length of their postoperative time. Fecal samples were used for gut microbiota analysis via 16s rRNA gene sequencing, blood examinations and plasma lipopolysaccharide measurements were also taken. Significant differences were observed in gut microbiota composition with regard to the relative bacterial abundances of 2 phyla, 7 families, and 15 genera. The lipopolysaccharide level was significantly higher in the SP group than in the HC group and were negatively associated with five bacterial families with low abundance in the SP group. The degree of the microbiota alteration increased with the length of the postoperative time. The PICRUSt analysis showed that the relative abundances of lipopolysaccharide biosynthesis proteins and lipopolysaccharide biosynthesis pathways were higher in the SP group and were positively associated with the plasma lipopolysaccharide level. Significant alterations were observed in the gut microbiota of the splenectomized patients and were associated with plasma lipopolysaccharide level. Further studies are needed to verify whether such alterations after splenectomy are related to an increased risk of complications.

Rabbit Microbiota Changes Throughout the Intestinal Tract

To gain insight into the importance of carefully selecting the sampling area for intestinal microbiota studies, cecal and fecal microbial communities of Caldes meat rabbit were characterized. The animals involved in the study were divided in two groups according to the feed intake level they received during the fattening period; ad libitum (n = 10) or restricted to 75% of ad libitum intake (n = 11). Cecum and internal hard feces were sampled from sacrificed animals. Assessment of bacterial and archaeal populations was performed by means of Illumina sequencing of 16S rRNA gene amplicons in a MiSeq platform. A total of 596 operational taxonomic units (OTUs) were detected using QIIME software. Taxonomic assignment revealed that microbial diversity was dominated by phyla Firmicutes (76.42%), Tenericutes (7.83%), and Bacteroidetes (7.42%); kingdom Archaea was presented at low percentage (0.61%). No significant differences were detected between sampling origins in microbial diversity or richness assessed using two alpha-diversity indexes: Shannon and the observed number of OTUs. However, the analysis of variance at genus level revealed a higher presence of genera Clostridium, Anaerofustis, Blautia, Akkermansia, rc4-4, and Bacteroides in cecal samples. By contrast, genera Oscillospira and Coprococcus were found to be overrepresented in feces, suggesting that bacterial species of these genera would act as fermenters at the end of feed digestion process. At the lowest taxonomic level, 83 and 97 OTUs in feces and cecum, respectively, were differentially represented. Multivariate statistical assessment revealed that sparse partial least squares discriminant analysis (sPLS-DA) was the best approach for this purpose. Interestingly, the majority of the most discriminative OTUs selected by sPLS-DA were found to be differentially represented between sampling origins in univariate analysis. Our study provides evidence that the choice of intestinal sampling area is relevant due to important differences in some taxa's relative abundance that have been revealed between rabbits' cecal and fecal microbiota. An appropriate sampling intestinal area should be chosen in each microbiota assessment.

Progress in primary prevention of colorectal cancer

Colorectal cancer (CRC) is one of the most common malignant tumors in the digestive tract, with high incidence and mortality. Most of CRC cases are diagnosed at the late stage, and the treatment effect is therefore poor. Thus, the prevention of CRC is particularly important. There have been many studies on the prevention of CRC in recent years. This paper will summarize the latest research on the primary prevention of CRC.