The Gut Microbiota during a Behavioral Weight Loss Intervention

Altered gut microbiota has been linked to obesity and may influence weight loss. We are conducting an ongoing weight loss trial, comparing daily caloric restriction (DCR) to intermittent fasting (IMF) in adults who are overweight or obese. We report here an ancillary study of the gut microbiota and selected obesity-related parameters at the baseline and after the first three months of interventions. During this time, participants experienced significant improvements in clinical health measures, along with altered composition and diversity of fecal microbiota. We observed significant associations between the gut microbiota features and clinical measures, including weight and waist circumference, as well as changes in these clinical measures over time. Analysis by intervention group found between-group differences in the relative abundance of Akkermansia in response to the interventions. Our results provide insight into the impact of baseline gut microbiota on weight loss responsiveness as well as the early effects of DCR and IMF on gut microbiota.     

Evaluation of immune response,microbiota, and blood markers after probiotic bacteria administration in obese mice induced by a high-fat diet

ObjectiveObesity is associated with alterations in intestinal microbiota and immunity. The aim of this study was to determine the effect of probiotic Lactobacillus casei CRL 431 administration on intestinal and humoral immune response, clinical parameters, and gut microbiota was evaluated using a high-fat diet to induce obesity in a mouse model.MethodsAdult mice received a conventional balanced diet or a high-fat diet supplemented with milk, milk fermented by Lactobacillus casei (FM), L. casei as suspension, or water over 60 d. Histology of liver and small intestine (SI), immunoglobulin A-positive cells and macrophages in SI, phagocytic activity of spleen and peritoneal macrophages, and humoral immune response to ovalbumin were studied. Clinical parameters in serum and gut microbiota were also analyzed.ResultsFM was the most effective supplement for decreasing body weight and clinical parameters in serum. The histology of liver and SI was also improved in obese mice given FM. These animals had increased numbers of immunoglobulin A-positive cells and macrophages in SI. The gut microbiota showed that obese mice given probiotics had increased Bacteroides and bifidobacteria. Administration of FM or L. casei as suspension enhanced the phagocytic activity of macrophages. The anti-ovalbumin specific immune response was not increased by any supplement assayed.ConclusionAdministration of probiotics to obese hosts improved the gut microbiota and the mucosal immunity altered by obesity, down-regulated some biochemical parameters in blood associated with metabolic syndrome, and decreased liver steatosis. These results demonstrate the potential use of probiotics in obese individuals to decrease the body weight and to improve the biochemical and immunologic parameters altered by obesity.     

Effects of Probiotics and Synbiotics on Weight Loss in Subjects with Overweight or Obesity: A Systematic Review

Intestinal microbiota has been shown to be a potential determining factor in the development of obesity. The objective of this systematic review is to collect and learn, based on the latest available evidence, the effect of the use of probiotics and synbiotics in randomized clinical trials on weight loss in people with overweight and obesity. A search for articles was carried out in PubMed, Web of science and Scopus until September 2021, using search strategies that included the terms “obesity”, “overweight”, “probiotic”, “synbiotic”, “Lactobacillus”, “Bifidobacterium” and “weight loss”. Of the 185 articles found, only 27 complied with the selection criteria and were analyzed in the review, of which 23 observed positive effects on weight loss. The intake of probiotics or synbiotics could lead to significant weight reductions, either maintaining habitual lifestyle habits or in combination with energy restriction and/or increased physical activity for an average of 12 weeks. Specific strains belonging to the genus Lactobacillus and Bifidobacterium were the most used and those that showed the best results in reducing body weight. Both probiotics and synbiotics have the potential to help in weight loss in overweight and obese populations.     

The Nutrition-Microbiota-Physical Activity Triad: An Inspiring New Concept for Health and Sports Performance

The human gut microbiota is currently the focus of converging interest in many diseases and sports performance. This review presents gut microbiota as a real “orchestra conductor” in the host’s physio(patho)logy due to its implications in many aspects of health and disease. Reciprocally, gut microbiota composition and activity are influenced by many different factors, such as diet and physical activity. Literature data have shown that macro- and micro-nutrients influence gut microbiota composition. Cumulative data indicate that gut bacteria are sensitive to modulation by physical activity, as shown by studies using training and hypoactivity models. Sports performance studies have also presented interesting and promising results. Therefore, gut microbiota could be considered a “pivotal” organ for health and sports performance, leading to a new concept: the nutrition-microbiota-physical activity triad. The next challenge for the scientific and medical communities is to test this concept in clinical studies. The long-term aim is to find the best combination of the three elements of this triad to optimize treatments, delay disease onset, or enhance sports performance. The many possibilities offered by biotic supplementation and training modalities open different avenues for future research.     

Behavioral Variables Associated with Obesity in Police Officers

Past research has documented that non-behavioral variables (such as long work hours, exposure to police stressors) are associated with obesity risk in police officers, but limited research has examined behavioral variables that might be targeted by Employee Assistance Programs for police weight management. The present study compared non-obese and obese officers for behavioral variables found associated with obesity in other adult samples: physical activity (cardiovascular, strength-training, stretching), sleep duration, and consumption of alcohol, fruit and vegetables, and snack foods. Participants included 172 male police officers who completed questionnaires to report height and weight, used to calculate body mass index (BMI = kg/m²) and to divide them into “non-obese” and “obese” groups. They also reported the above behaviors and six non-behavioral variables found associated with obesity risk: age, health problems, family support, police work hours, police stressors, police support. ANCOVAs compared each behavioral variable across obesity status (non-obese, obese), with the six non-behavioral variables used as covariates. Results revealed that cardiovascular and strength-training physical activity were the only behavioral variables that differed significantly between non-obese and obese police officers. The use of self-reported height and weight values may provide Employee Assistance Program with improved cost, time, and officer participation.     

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.     

Effects of Anthocyanin on Intestinal Health: A Systematic Review

Intestinal health relies on the association between the mucosal immune system, intestinal barrier and gut microbiota. Bioactive components that affect the gut microbiota composition, epithelial physical barrier and intestinal morphology were previously studied. The current systematic review evaluated evidence of anthocyanin effects and the ability to improve gut microbiota composition, their metabolites and parameters of the physical barrier; this was conducted in order to answer the question: “Does food source or extract of anthocyanin promote changes on intestinal parameters?”. The data analysis was conducted following the PRISMA guidelines with the search performed at PubMed, Cochrane and Scopus databases for experimental studies, and the risk of bias was assessed by the SYRCLE tool. Twenty-seven studies performed in animal models were included, and evaluated for limitations in heterogeneity, methodologies, absence of information regarding allocation process and investigators’ blinding. The data were analyzed, and the anthocyanin supplementation demonstrated positive effects on intestinal health. The main results identified were an increase of Bacteroidetes and a decrease of Firmicutes, an increase of short chain fatty acids production, a decrease of intestinal pH and intestinal permeability, an increase of the number of goblet cells and tight junction proteins and villi improvement in length or height. Thus, the anthocyanin supplementation has a potential effect to improve the intestinal health. PROSPERO (CRD42020204835).     

Impact of Exercise on Gut Microbiota in Obesity

Physical activity, exercise, or physical fitness are being studied as helpful nonpharmacological therapies to reduce signaling pathways related to inflammation. Studies describing changes in intestinal microbiota have stated that physical activity could increase the microbial variance and enhance the ratio of Firmicutes/Bacteroidetes, and both actions could neutralize the obesity progression and diminish body weight. The aim of this review is to provide an overview of the literature describing the relationship between physical activity profiles and gut microbiota and in obesity and some associated comorbidities. Promoting physical activity could support as a treatment to maintain the gut microbiota composition or to restore the balance toward an improvement of dysbiosis in obesity; however, these mechanisms need to be studied in more detail. The opportunity to control the microbiota by physical activity to improve health results and decrease obesity and related comorbidities is very attractive. Nevertheless, several incompletely answered questions need to be addressed before this strategy can be implemented.     

Effects of Lactobacillus curvatus HY7601 and Lactobacillus plantarum KY1032 on Overweight and the Gut Microbiota in Humans: Randomized,Double-Blinded,Placebo-Controlled Clinical Trial

Obesity and overweight are closely related to diet, and the gut microbiota play an important role in body weight and human health. The aim of this study was to explore how Lactobacillus curvatus HY7601 and Lactobacillus plantarum KY1032 supplementation alleviate obesity by modulating the human gut microbiome. A randomized, double-blind, placebo-controlled study was conducted on 72 individuals with overweight. Over a 12-week period, probiotic groups consumed 1 × 10¹⁰ colony-forming units of HY7601 and KY1032, whereas the placebo group consumed the same product without probiotics. After treatment, the probiotic group displayed a reduction in body weight (p < 0.001), visceral fat mass (p < 0.025), and waist circumference (p < 0.007), and an increase in adiponectin (p < 0.046), compared with the placebo group. Additionally, HY7601 and KY1032 supplementation modulated bacterial gut microbiota characteristics and beta diversity by increasing Bifidobacteriaceae and Akkermansiaceae and decreasing Prevotellaceae and Selenomonadaceae. In summary, HY7601 and KY1032 probiotics exert anti-obesity effects by regulating the gut microbiota; hence, they have therapeutic potential for preventing or alleviating obesity and living with overweight.     

Dietary Whole Grain–Microbiota Interactions: Insights into Mechanisms for Human Health

This article summarizes the presentations from the “Dietary Whole Grain–Microbiota Interactions: Insights into Mechanisms for Human Health” symposium held at the ASN Scientific Sessions and Annual Meeting at Experimental Biology 2014 in San Diego, CA, on 28 April 2014. The symposium focused on the interactive effects of whole grains and nondigestible carbohydrates with the gut microbiota with the goal of identifying the benefits of whole grains that are mediated through their effects on the gut microbiome. This theme was addressed by 4 speakers, each with their own unique perspective. Dr. Michael Lefevre reviewed the impact of whole grains on markers of subclinical inflammation, drawing examples from epidemiologic literature, clinical trials, and animal experiments. Dr. Knud Erik Bach Knudsen discussed data from studies he conducted to identify specific carbohydrates that enhance colonic butyrate production. Dr. Michael Keenan presented a chronology of his research program devoted to understanding the mechanisms underlying the metabolic effects of resistant starch, particularly high-amylose maize. Dr. Jens Walter emphasized that whole grains can impact gut microbial ecology by increasing microbial diversity and inducing compositional alterations, some of which are considered to have beneficial effects on the host.The concept of microbial-mammalian cometabolism as a key influence on human health is a hot topic that involves the integration of nutrition, metabolomics, microbiology, genomics/metagenomics, and food science. The role of the gut microbiome in optimizing health has received considerable attention in the nutrition community. Rather than review the sweeping research efforts in this rapidly expanding field, this symposium, entitled “Dietary Whole Grain–Microbiota Interactions: Insights into Mechanisms for Human Health,” focused on the interactive effects of whole grains and nondigestible carbohydrates with the gut microbiota with the goal of identifying the benefits of whole grains that are mediated through their effects on the gut microbiome. The objectives of this symposium were as follows: 1) to understand the current research methods used to study nutrition and gut microbiota; 2) to understand the roles of particular bacteria in the microbial community of the human large intestine; and 3) to present novel hypotheses related to the role of gut microbiota in improved human health. Four distinguished speakers addressed the symposium theme, each providing their own unique perspective, describing cutting-edge science in this field and testing key hypotheses relative to the mechanisms of the well-known health benefits of whole grains.The symposium’s first speaker was Dr. Michael Lefevre, USTAR Professor at Utah State University’s Center for Human Nutrition Studies and the Scientific Director of the Applied Nutrition Research team. Lefevre’s presentation, “Whole grains and markers of subclinical inflammation,” first reviewed epidemiologic evidence of the role of whole grains in promoting good health and affecting disease risk specific to inflammation. Cohort studies reveal that small changes in risk could be attributable to whole-grain consumption, but interpretation of this effect is confounded by the possibility that use of whole grains may indicate a healthier lifestyle. In contrast to epidemiologic studies, interventional studies do not demonstrate a clear effect of increased whole-grain consumption on markers of inflammation. Only 1 study found a decrease in circulating C-reactive protein concentrations, whereas all other studies reviewed found no change in markers of inflammation. Issues related to insufficient length of intervention, extent of dietary control, population selection, types of whole grains, and lack of a direct anti-inflammatory effect may underlie these discrepant findings. These findings have been summarized previously in a published review article (1). In particular, he emphasized that one cannot assume that all whole grains have similar physiologic effects. New research conducted in his laboratory demonstrates that whole wheat, whole oats, and whole corn have unique effects on inflammatory responses, metabolism, and gut microbiota composition.The second speaker was Dr. Knud Erik Bach Knudsen, Professor and Head of the Research Unit on Molecular Nutrition and Cell Biology in the Department of Animal Science, Aarhus University, Denmark. In his presentation, “Microbial degradation and impact on short-chain fatty acids of whole grain complex carbohydrates in the gut,” Knudsen posited that the carbohydrates found in cereals may have major effects on butyrate production in the large intestine and described a series of studies he conducted to identify specific carbohydrates that enhance colonic butyrate production. Butyrate is targeted for its beneficial effects on gut health, including maintaining the integrity of the coloncytes. Systemically, this short-chain FA may also promote insulin sensitivity and glucose homeostasis and reduce food intake through release of gut peptides associated with satiety. Knudsen has found that arabinoxylan-rich rye fractions produce the highest level of colonic butyrate production and explained how this carbohydrate source might be used to improve health.The third speaker was Dr. Michael J. Keenan, Associate Professor of Human Ecology at the Louisiana Agricultural Experimental Station at Louisiana State University, Baton Rouge, LA. Keenan’s presentation, “Role of resistant starch in improving gut health and metabolic syndrome,” included a chronology of his research program devoted to understanding the mechanisms underlying the metabolic effects of resistant starch, particularly high-amylose maize. He has studied the impact of resistant starches from grains on gut microbial profiles and markers of health in gestational diabetes and in both dietary and genetic animal models of obesity. The primary event in resistant starch action is the manipulation of the gut microbiome and resulting fermentation products. Keenan reported that microbial community shifts associated with resistant starch consumption include increases in Lactobacillus, Bifidobacterium, and Akkermansia. Along with these shifts in microbiota, insulin sensitivity improves, possibly due to these following secondary mechanisms: 1) improved gut health and gut barrier function, which lowers the leakage of inflammatory products from the gut to the blood stream; and/or 2) butyrate stimulation of enteroendocrine cells to increase production and secretion of glucagon-like peptide 1, which is known to improve insulin sensitivity and reduce body fat.The fourth speaker was Dr. Jens Walter, Associate Professor and Campus Alberta Innovation Program Chair for Nutrition, Microbes, and Gastrointestinal Health at the University of Alberta, Edmonton, Canada. Walter’s presentation, “The role of the gastrointestinal microbiota in the health benefits of whole grains,” began with the suggestion that dysbiosis of the intestinal microbiota is associated with a large number of the chronic diseases prevalent in Western societies. This dysbiosis, characterized by decreased diversity of the microbiota, is the result of a modern lifestyle that includes a diet low in fiber and high in simple sugars, fats, and protein—a diet that provides poor nutritional support for microbes inhabiting the large intestine. Walter emphasized that whole grains can impact gut microbial ecology by increasing microbial diversity and inducing compositional alterations, some of which are considered to have beneficial effects on the host. For example, in studies with whole-grain barley, brown rice, and the combination of these grains, he found that inclusion of both whole grains led to increases in the Firmicutes:Bacteroidetes ratio. Also, he found that whole-grain barley consumption resulted in enrichments of the genera Roseburia, Bifidobacterium, and Dialister, and the species Eubacterium rectale, Roseburia faecis, and Roseburia intestinalis. These changes were seen despite large interindividual variation in response to the whole grains. The grain combination also produced decreases in peak postprandial glucose and plasma IL-6; the latter decrease was related to abundance of specific taxa.In summary, new data were presented to demonstrate that consumption of whole grains and complex nondigestible carbohydrates found in whole grains can significantly shift the microbial ecology of the large bowel. These changes were associated with alterations in markers of immunologic function and with improvements in blood glucose control. Collectively, the speakers presented state-of-the-art concepts aimed to determine the role of the gut microbiota in conferring health benefits of whole grains. Important themes highlighted by these presentations were as follows: 1) the carbohydrates contained in whole grains vary in complexity and structure and, as a result, have different effects on the microbiota; 2) other diet components such as fat or protein may influence the response to whole grains; and 3) individual responses to whole grains are varied and influenced by phenotype and genotype. We were also reminded that, in addition to the complex carbohydrates, whole grains contain other bioactive components, such as lignans and polyphenols, that may influence metabolic and immunologic functions independently or in concert with shifts in the microbiota. Clearly, many questions remain to be answered, but the work presented by our speakers has established a strong foundation for future exploration of whole grain–microbiota interactions.     

Fiber Consumption Mediates Differences in Several Gut Microbes in a Subpopulation of Young Mexican Adults

Diet is a determinant for bodyweight and gut microbiota composition. Changes in dietary patterns are useful for the prevention and management of overweight and obesity. We aim to evaluate diet behavior and its potential association with selected gut bacteria and body weight among Mexican young adults. Mexican college students aged between 18 and 25 (normal-weight, overweight, and obese) were recruited. Anthropometric variables were recorded. A validated food frequency questionnaire was applied to all the participants. The percentages of macronutrients, fiber, and energy were calculated, and fecal samples were analyzed by real-time-qPCR to quantify selected gut bacteria. All the participants showed an unbalanced dietary pattern. However, the consumption of fruits, non-fat cereals, and oils and fats without protein were higher in the normal-weight individuals. In the overweight/obese participants, fiber intake did not correlate with the microbial variables, while Kcal from protein and Clostridium leptum correlated positively with Lactobacillus. Similarly, Clostridium coccoides-Eubacterium rectale correlated with Akkermansia muciniphila. In the normal-weight participants, Clostridium leptum and Lactobacillus correlated positively with Clostridium coccoides-Eubacterium rectale and Bifidobacterium, respectively, and Bacteroidetes negatively with Akkermansia muciniphila. In conclusion, a higher fiber intake had a positive impact on body weight and bacterial gut composition in this Mexican population of college students.     

Obesity Modulates the Gut Microbiome in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is an aggressive, molecularly heterogeneous subtype of breast cancer. Obesity is associated with increased incidence and worse prognosis in TNBC through various potential mechanisms. Recent evidence suggests that the gut microbiome plays a central role in the progression of cancer, and that imbalances or dysbiosis in the population of commensal microbiota can lead to inflammation and contribute to tumor progression. Obesity is characterized by low-grade inflammation, and gut dysbiosis is associated with obesity, chronic inflammation, and failure of cancer immunotherapy. However, the debate on what constitutes a “healthy” gut microbiome is ongoing, and the connection among the gut microbiome, obesity, and TNBC has not yet been addressed. This study aims to characterize the role of obesity in modulating the gut microbiome in a syngeneic mouse model of TNBC. 16S rRNA sequencing and metagenomic analyses were performed to analyze and annotate genus and taxonomic profiles. Our results suggest that obesity decreases alpha diversity in the gut microbiome. Metagenomic analysis revealed that obesity was the only significant factor explaining the similarity of the bacterial communities according to their taxonomic profiles. In contrast to the analysis of taxonomic profiles, the analysis of variation of functional profiles suggested that obesity status, tumor presence, and the obesity–tumor interaction were significant in explaining the variation of profiles, with obesity having the strongest correlation. The presence of tumor modified the profiles to a greater extent in obese than in lean animals. Further research is warranted to understand the impact of the gut microbiome on TNBC progression and immunotherapy.     

The Effects of High Fiber Rye,Compared to Refined Wheat,on Gut Microbiota Composition,Plasma Short Chain Fatty Acids,and Implications for Weight Loss and Metabolic Risk Factors (the RyeWeight Study)

Consumption of whole grain and cereal fiber have been inversely associated with body weight and obesity measures in observational studies but data from large, long-term randomized interventions are scarce. Among the cereals, rye has the highest fiber content and high rye consumption has been linked to increased production of gut fermentation products, as well as reduced risks of obesity and metabolic disease. The effects on body weight and metabolic risk factors may partly be mediated through gut microbiota and/or their fermentation products. We used data from a randomized controlled weight loss trial where participants were randomized to a hypocaloric diet rich in either high fiber rye foods or refined wheat foods for 12 weeks to investigate the effects of the intervention on gut microbiota composition and plasma short chain fatty acids, as well as the potential association with weight loss and metabolic risk markers. Rye, compared to wheat, induced some changes in gut microbiota composition, including increased abundance of the butyrate producing Agathobacter and reduced abundance of [Ruminococcus] torques group, which may be related to reductions in low grade inflammation caused by the intervention. Plasma butyrate increased in the rye group. In conclusion, intervention with high fiber rye foods induced some changes in gut microbiota composition and plasma short chain fatty acid concentration, which were associated with improvements in metabolic risk markers as a result of the intervention.     

Non-Celiac Gluten/Wheat Sensitivity: Clinical Characteristics and Microbiota and Mycobiota Composition by Response to the Gluten Challenge Test

The aims of this observational “proof-of-concept” study were to analyze the clinical/psychological characteristics and gut microbiota/mycobiota composition of individuals with suspected non-celiac gluten/wheat sensitivity (NCGS/WS) according to responses to the double-blind-placebo-controlled (DBPC) crossover gluten challenge test. Fifty individuals with suspected NCGS/WS were subjected to the DBPC challenge test; anthropometric measurements, psychometric questionnaires, and fecal samples were collected. Twenty-seven (54%) participants were gluten responsive (NCGS), and 23 were placebo responsive, with an order effect. NCGS individuals displayed a significantly lower risk of eating disorders and a higher mental health score when compared to placebo-responsive participants, confirmed by multiple logistic regression analyses (OR = 0.87; 95% CI 0.76–0.98, p = 0.021, and OR = 1.30; 95% CI 1.06–1.59, p = 0.009, respectively). Principal coordinate analyses based on microbiota composition showed a separation by the DBPC response (p = 0.039). For Bacteroides (p = 0.05) and Parabacteroides (p = 0.007), the frequency of amplicon sequence variants was lower, and that for Blautia (p = 0.009) and Streptococcus (p = 0.004) was higher in NCGS individuals at multiple regression analyses. No difference in the mycobiota composition was detected between the groups. In conclusion, almost half of the individuals with suspected gluten sensitivity reported symptoms with placebo; they showed lower mental health scores, increased risk for eating disorders, and a different gut microbiota composition.     

Genistein Reduces the Risk of Local Mammary Cancer Recurrence and Ameliorates Alterations in the Gut Microbiota in the Offspring of Obese Dams

The risk of recurrence of estrogen receptor-positive breast cancer remains constant, even 20 years after diagnosis. Recurrence may be more likely in patients pre-programmed for it already in the womb, such as in the daughters born to obese mothers. Maternal obesity persistently alters offspring’s gut microbiota and impairs tumor immune responses. To investigate if the gut dysbiosis is linked to increased risk of mammary cancer recurrence in the offspring of obese rat dams, we fed adult offspring genistein which is known to have beneficial effects on the gut bacteria. However, the effects of genistein on breast cancer remain controversial. We found that genistein intake after tamoxifen response prevented the increased risk of local recurrence in the offspring of obese dams but had no effect on the control offspring. A significant increase in the abundance of inflammatory Prevotellaceae and Enterobacteriaceae, and a reduction in short-chain fatty acid producing Clostridiaceae was observed in the offspring of obese dams. Genistein supplementation reversed these changes as well as reversed increased gut metabolite N-acetylvaline levels which are linked to increased all-cause mortality. Genistein supplementation also reduced genotoxic tyramine levels, increased metabolites improving pro-resolving phase of inflammation, and reversed the elevated tumor mRNA expression of multiple immunosuppressive genes in the offspring of obese dams. If translatable to breast cancer patients, attempts to prevent breast cancer recurrences might need to focus on dietary modifications which beneficially modify the gut microbiota.     

Functional Fiber Reduces Mice Obesity by Regulating Intestinal Microbiota

Obesity may cause metabolic syndrome and has become a global public health problem, and dietary fibers (DF) could alleviate obesity and metabolic syndrome by regulating intestinal microbiota. We developed a functional fiber (FF) with a synthetic mixture of polysaccharides, high viscosity, water-binding capacity, swelling capacity, and fermentability. This study aimed to investigate the effect of FF on obesity and to determine its prevention of obesity by modulating the gut microbiota. Physiological, histological, and biochemical parameters, and gut microbiota composition were investigated in the following six groups: control group (Con), high-fat diet group (HFD), low-fat diet group (LFD, conversion of HFD to LFD), high-fat +8% FF group (8% FF), high-fat +12% FF group (12% FF), and high-fat +12% FF + antibiotic group (12% FF + AB). The results demonstrated that 12% FF could promote a reduction in body weight and epididymal adipocyte area, augment insulin sensitivity, and stimulate heat production from brown adipose tissue (BAT) (p < 0.05). Compared with the HFD, 12% FF could also significantly improve the intestinal morphological integrity, attenuate systemic inflammation, promote intestinal microbiota homeostasis, and stabilize the production of short-chain fatty acids (SCFAs) (p < 0.05). Consistent with the results of 12% FF, the LFD could significantly reduce the body weight and epididymal adipocyte area relative to the HFD (p < 0.05), but the LFD and HFD showed no significant difference (p > 0.05) in the level of inflammation and SCFAs. Meanwhile, 12% FF supplementation showed an increase (p < 0.05) in the abundance of the Bifidobacterium, Lactococcus, and Coprococcus genus in the intestine, which had a negative correlation with obesity and insulin resistance. Additionally, the treatment with antibiotics (12% FF + AB) could inhibit the effect of FF in the HFD. The Kyoto Encyclopedia of Genes and Genomes (KEGG) function prediction revealed that 12% FF could significantly inhibit the cyanogenic amino acid metabolic pathway and decrease the serum succinate concentration relative to the HFD group. The overall results indicate that 12% FF has the potential to reduce obesity through the beneficial regulation of the gut microbiota and metabolites.     

Effects of gut microbes on nutrient absorption and energy regulation

Malnutrition may manifest as either obesity or undernutrition. Accumulating evidence suggests that the gut microbiota plays an important role in the harvest, storage, and expenditure of energy obtained from the diet. The composition of the gut microbiota has been shown to differ between lean and obese humans and mice; however, the specific roles that individual gut microbes play in energy harvest remain uncertain. The gut microbiota may also influence the development of conditions characterized by chronic low-level inflammation, such as obesity, through systemic exposure to bacterial lipopolysaccharide derived from the gut microbiota. In this review, the role of the gut microbiota in energy harvest and fat storage is explored, as well as differences in the microbiota in obesity and undernutrition.     

Preliminary Report on Intestinal Flora Disorder,Faecal Short-Chain Fatty Acid Level Decline and Intestinal Mucosal Tissue Weakening Caused by Litchi Extract to Induce Systemic Inflammation in HFA Mice

Certain foods are known as “heating” foods in Chinese medicine. Over-consumption of these foods can lead to symptoms known as “heating up”. These symptoms have been shown to be symptoms of systemic low-grade inflammation. However, the mechanism by which these foods cause inflammation is not clear. In this preliminary study, we investigated dysbacteriosis of the gut microbiota as a possible cause of inflammation by litchi, a typical “heating” food. A human flora-associated (HFA) mouse model (donor: n = 1) was constructed. After gavaging the mice with litchi extract suspension at low, medium and high doses (400, 800, 1600 mg/kg·d⁻¹, respectively) (n = 3) for 7 days, the serum levels of inflammatory cytokines, gut microbiota, the concentration of SCFAs and the integrity of the intestinal mucosal barrier were measured. The results revealed significant increases in the abundance of Prevotella and Bacteroides. A significant increase in the abundance of Bilophila and a decrease in Megasomonas was observed in the high-dose group. High-dose litchi intervention led to a decrease of most SCFA levels in the intestine. It also caused a more than two-fold increase in the serum TNF-α level and LPS level but a decrease in the IL-1β and IL-6 levels. Medium- and high-dose litchi intervention caused widening of the intestinal epithelial cell junction complex and general weakening of the intestinal mucosal barrier as well as reduced energy conversion efficiency of the gut microbiota. These data suggest that litchi, when consumed excessively, can lead to a low degree of systematic inflammation and this is linked to its ability to cause dysbacteriosis of the gut microbiota, decrease SCFAs and weaken the intestinal mucosal tissues.     

学龄儿童肥胖与肠道菌群多样性及菌属丰度的关联研究

目的分析学龄肥胖儿童和正常体重儿童肠道菌群多样性差异, 识别肥胖儿童肠道特征菌属, 为后续相关机制研究和学龄儿童肥胖的防治提供依据。方法基于2016年在上海市嘉定区某小学建立的研究队列人群, 将2016-2018年3年均处肥胖状态的儿童共63名纳入肥胖组, 其中男生43名, 女生20名。在3年均为正常体重的儿童中, 根据年龄、性别和所在班级, 将其与肥胖组儿童进行1∶1匹配, 共选择63名纳入对照组。采用问卷收集儿童基本信息、饮食状况、母乳喂养等情况, 收集两组儿童的粪便样本并进行16S rDNA测序。对质量优化后的测序序列按照97%相似性进行可操作分类单元聚类及物种注释。分析肥胖组和对照组儿童肠道菌群多样性及菌属丰度差异。计算肠道菌群的Ace、Chao1、Shannon、Simpson 4种α多样性指数, 并利用主坐标分析, 在非加权Unifrac距离和加权Unifrac距离的基础上表示β多样性。使用相似性分析(ANOSIM)比较两组β多样性的差异。利用STAMP软件挑选出两组儿童共有菌属中的差异细菌, 并利用广义线性模型(GLM)分析肥胖与α多样性以及显著差异菌属的关联。结果肥胖组...     

Relative contributions of health behaviours versus social factors on perceived and objective weight status in Canadian adolescents

ObjectivesPublic health interventions for adolescent “obesity prevention” have focused predominantly on individualistic health behaviours (e.g., diet and physical activity) at the expense of recognizing body weight diversity and the array of social factors (e.g., stigma and discrimination of marginalized identities) that may be linked to weight status. Research is needed to examine the extent to which individualistic health behaviours versus social factors contribute to weight status in adolescents. As such, the aim of this study was to investigate the relative contribution of individualistic health behaviours versus social factors to objective and perceptual indices of weight status.MethodsCross-sectional survey data were collected as part of the Toronto Public Health Student Survey and comprised students 12 to 19 years of age (N = 5515). Measures included perceived and objective weight status, social and demographic factors (e.g., gender, sexual orientation, school connectedness), and health behaviours (e.g., physical activity, nutritious consumption).ResultsFindings from latent variable regression models partially supported hypotheses, whereby social factors (i.e., age, sex, socio-economic access, sexual minority status) contribute similar amounts of variance, or relatively more variance in weight indices, compared to health behaviours (e.g., physical activity, nutritious consumption).ConclusionContrary to traditional views of adolescent weight status, physical activity (i.e., school-based, individual, active transport) and nutritious consumption (i.e., fruits, vegetables, milk) were not associated with weight status, when considering social factors. These findings challenge the utility of public health approaches that target individualistic behaviours as critical risk factors in “obesity prevention” efforts in adolescence.