Gut Bacterial Families Are Associated with Body Composition and Metabolic Risk Markers in School-Aged Children in Rural Mexico

Exploring the Dynamic Relationship between the Gut Microbiome and Body Composition across the Human Lifespan: A Systematic Review

This systematic review aimed to identify different gut microbiome profiles across the human lifespan and to correlate such profiles with the body composition. PubMed, Scopus, and Cochrane were searched from inception to March 2022. Sixty studies were included in this systematic review. Overall, the gut microbiome composition in overweight participants exhibited decreased α-diversity, decreased levels of the phylum Bacteroidetes and its taxa, and increased levels of the phylum Firmicutes, its taxa, and the Firmicutes/Bacteroidetes ratio, in comparison to normal-weight participants. Other body composition parameters showed similar correlations. Fat mass and waist circumference were found to correlate positively with the Firmicutes taxa and negatively with the Bacteroidetes taxa. In contrast, lean body mass and muscle mass demonstrated a positive correlation with the Bacteroidetes taxa. Notably, these correlations were more pronounced in athletes than in obese and normal-weight individuals. The composition of the gut microbiome is evidently different in overweight individuals or athletes of all age groups, with the former tending towards decreased Bacteroidetes taxa and increased Firmicutes taxa, while a reversed relationship is observed concerning athletes. Further studies are needed to explore the dynamic relationship between energy intake, body composition, and the gut microbiome across the human lifespan.

Spent coffee grounds and its antioxidant dietary fiber promote different colonic microbiome signatures: Benefits for subjects with chronodisruption

Chronodisruption, commonly displayed by people living with obesity (PLO), is linked to colonic microbiota dysbiosis, and may increase the risk of many chronic non-communicable diseases, whereas dietary interventions-called chrononutrition may mitigate it. We evaluated the in vitro effects of spent coffee grounds (SCG), and their antioxidant dietary fiber (SCG-DF) on the colonic microbiota of an obese donor displaying dysbiosis and chronodisruption. Basal microbiota pattern was associated with an increased risk of non-communicable chronic diseases. Both samples decrease species richness and increase microbiota diversity (p < 0.05; Chao and Shannon index, respectively), positively enhancing Firmicutes/Bacteroidetes index (SCG, p < 0.04; SCG-DF, p < 0.02). SCG and SCG-DF modulated the microbiota, but SCG-DF induced greater changes, significantly increasing. p_Actonobacterias (SCG p < 0.04; SCG-DF, p < 0.02), and reducing g_Alistipes; s_putredinis, g_Prevotella;s_copri. The highest increase was displayed by p_Proteobacteria (f_Desulfovibrionaceae and f_Alcanigenaceae, p < 0.05), while g_Haemophilus; s_parainfluenzae decreased (p < 0.05). However, neither SCG nor SCG-DF modulated g_Alistipes (evening-type colonic microbial marker) beneficially. SCG and SCG-DF reduced (p < 0.05) g_Lachnospira, a microbial evening-type marker, among other microbial populations, of an obese donor displaying chronodisruption and dysbiosis. SCG and SCG-DF displayed a prebiotic effect with the potential to mitigate diseases linked to chronodisruption.

From-Toilet-to-Freezer: A Review on Requirements for an Automatic Protocol to Collect and Store Human Fecal Samples for Research Purposes

The composition, viability and metabolic functionality of intestinal microbiota play an important role in human health and disease. Studies on intestinal microbiota are often based on fecal samples, because these can be sampled in a non-invasive way, although procedures for sampling, processing and storage vary. This review presents factors to consider when developing an automated protocol for sampling, processing and storing fecal samples: donor inclusion criteria, urine-feces separation in smart toilets, homogenization, aliquoting, usage or type of buffer to dissolve and store fecal material, temperature and time for processing and storage and quality control. The lack of standardization and low-throughput of state-of-the-art fecal collection procedures promote a more automated protocol. Based on this review, an automated protocol is proposed. Fecal samples should be collected and immediately processed under anaerobic conditions at either room temperature (RT) for a maximum of 4 h or at 4 °C for no more than 24 h. Upon homogenization, preferably in the absence of added solvent to allow addition of a buffer of choice at a later stage, aliquots obtained should be stored at either -20 °C for up to a few months or -80 °C for a longer period-up to 2 years. Protocols for quality control should characterize microbial composition and viability as well as metabolic functionality.

Multigenerational adversity impacts on human gut microbiome composition and socioemotional functioning in early childhood

Adversity exposures in the prenatal and postnatal period are associated with an increased risk for psychopathology, which can be perpetuated across generations. Nonhuman animal research highlights the gut microbiome as a putative biological mechanism underlying such generational risks. In a sample of 450 mother-child dyads living in Singapore, we examined associations between three distinct adversity exposures experienced across two generations-maternal childhood maltreatment, maternal prenatal anxiety, and second-generation children's exposure to stressful life events-and the gut microbiome composition of second-generation children at 2 y of age. We found distinct differences in gut microbiome profiles linked to each adversity exposure, as well as some nonaffected microbiome features (e.g., beta diversity). Remarkably, some of the microbial taxa associated with concurrent and prospective child socioemotional functioning shared overlapping putative functions with those affected by adversity, suggesting that the intergenerational transmission of adversity may have a lasting impact on children's mental health via alterations to gut microbiome functions. Our findings open up a new avenue of research into the underlying mechanisms of intergenerational transmission of mental health risks and the potential of the gut microbiome as a target for intervention.

Interaction of beta-glucans with gut microbiota: Dietary origins, structures, degradation, metabolism, and beneficial function

Beta-glucan (BG), a polysaccharide comprised of interfacing glucose monomers joined via beta-glycosidic linkages, can be defined as a type of dietary fiber with high specificity based on its interaction with the gut microbiota. It can induce similar interindividual microbiota responses, thereby having beneficial effects on the human body. In this paper, we review the four main sources of BG (cereals, fungi, algae, and bacteria) and their differences in structure and content. The interaction of BG with gut microbiota and the resulting health effects have been highlighted, including immune enhancement, regulation of serum cholesterol and insulin levels, alleviation of obesity and improvement of cognitive disorders. Finally, the application of BG in food products and its beneficial effects on the gut microbiota of consumers were discussed. Although some of the mechanisms of action remain unclear, revealing the beneficial functions of BG from the perspective of gut microbiota can help provide theoretical support for the development of diets that target the regulation of microbiota.

Obesogenic Diet Cycling Produces Graded Effects on Cognition and Microbiota Composition in Rats

SCOPE

The effects of diet cycling on cognition and fecal microbiota are not well understood.

METHOD AND RESULTS

Adult male Sprague-Dawley rats were cycled between a high-fat, high-sugar "cafeteria" diet (Caf) and regular chow. The impairment in place recognition memory produced by 16 days of Caf diet was reduced by switching to chow for 11 but not 4 days. Next, rats received 16 days of Caf diet in 2, 4, 8, or 16-day cycles, each separated by 4-day chow cycles. Place recognition memory declined from baseline in all groups and was impaired in the 16- versus 2-day group. Finally, rats received 24 days of Caf diet continuously or in 3-day cycles separated by 2- or 4-day chow cycles. Any Caf diet access impaired cognition and increased adiposity relative to controls, without altering hippocampal gene expression. Place recognition and adiposity were the strongest predictors of global microbiota composition. Overall, diets with higher Caf > chow ratios produced greater spatial memory impairments and larger shifts in gut microbiota species richness and beta diversity.

CONCLUSION

Results suggest that diet-induced cognitive deficits worsen in proportion to unhealthy diet exposure, and that shifting to a healthy chow for at least a week is required for recovery under the conditions tested here.

Inflammatory Mediators and Type 2 Diabetes Risk Factors before and in Response to Lifestyle Intervention among Latino Adolescents with Obesity

Obesity is associated with chronic inflammation that may contribute to T2D among youth. We examined the association between inflammatory biomarkers and insulin sensitivity and β-cell function and response to lifestyle intervention among Latino youth with obesity. Latino youth (n = 64) were randomized to six months of lifestyle intervention (INT, n = 40) or usual care (UC, n = 24). INT included nutrition education and physical activity. UC involved meeting with a pediatric endocrinologist and registered dietitian to discuss healthy lifestyles. At baseline, multiple linear regression assessed fasting serum interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), monocyte chemoattractant protein-1 (MCP-1), high-molecular weight adiponectin (HMW Adpn), IL-10, IL-1 receptor antagonist (IL-1ra) as predictors of insulin sensitivity (whole-body insulin sensitivity index, WBISI) and β-cell function (oral disposition index, oDI). Changes in outcomes between groups were assessed using covariance pattern models. At baseline, MCP-1 (β ± SE, -0.12 ± 0.05, p = 0.027) and IL-1ra (-0.03 ± 0.01, p = 0.005) were negatively associated with WBISI. Treatment effects were not observed for inflammatory markers. WBISI was significantly increased among both INT (from 1.8 ± 0.2 to 2.6 ± 0.4, p = 0.005) and UC (from 1.6 ± 0.2 to 2.8 ± 0.5, p = 0.002) with no significant differences between the groups. Obesity-related inflammatory mediators were associated with T2D risk factors but were unaffected by lifestyle intervention among Latino youth.

Body Mass Index and Gut Microbiome: A Cluster-Randomized, Controlled, Pilot Feasibility Study

Background: Prebiotic fiber has been examined as a way to foster gut bacteria less associated with obesity. Tests of prebiotic fiber in reducing obesity have been conducted mainly in animals, adults, and Caucasians when the highest obesity rates are in African American and Latinx youth. Response to prebiotic fiber is determined by the pre-existing intestinal microbiota. The type of microbiota varies based on diet and physical activity (PA), so it is important to examine acceptability and response to prebiotic fiber in those most at risk for obesity. Methods: This cluster-randomized, controlled feasibility trial included an online program designed to improve diet and PA along with administration of a prebiotic fiber for 12 weeks in 123 students of 4th and 5th grade where 98% were eligible for free or reduced-fee lunch. Of these 56% were male; 71% Latinx; 15% African American; and 14% other. Results: Decrease in body fat (BF) was associated with higher pretest BF. Lower body mass index (BMI) was associated with decrease in fecal Tenericutes and increase in Actinobacteria. Conclusions: Prebiotic fiber can be helpful in supporting healthy weight, so inclusion in culturally congruent foods usually eaten by children from groups at high risk for obesity should be considered following additional studies. Determining those most responsive to prebiotic fibers can also permit individual recommendations for greater inclusion in usual diet choices. Clinical Trial Registration Number NCT05671731.

Bioactive composition and modulatory effects of Hed-Tean-Rad Mushroom, Macrocybe crassa on gut microbiota

Macrocybe crassa (or Tricholoma crassum) is a nutrient-dense wild edible mushroom native to Thailand. The mushroom extract and its constituents have remarkable biological characteristics, but the influence of the powder on the human gut microbiota is unknown. This study investigated the bioactive composition and modulatory properties of M. crassa powder on gut microbial composition and short-chain fatty acids (SCFA) production. The fermentation of M. crassa powder by human intestinal microbiota released SCFA, mainly acetic acid, propionic acid and butyric acid. M. crassa powder significantly modulated the microbiota by increasing the relative abundances of Bifidobacterium, Lactobacillus/Enterococcus group, Atopobium, Bacteroidaceae/Prevotellaceae, and C. coccoides. F. prausnitzii, Roseburia genus, C. histolyticum and C. cluster IX, similar to that of Fructooligosaccharides (FOS). With M. crassa powder, high content of propionic acid was observed, as well as a number of Bacteroidaceae/Prevotellaceae and C. cluster IX. On the other hand, FOS caused a high acetic acid concentration and a population of Bifidobacterium spp., Atopobium cluster, Bacteroidaceae/Prevotellaceae, and C. coccoides. Therefore, this work will significantly contribute to filling the knowledge gap and revealing the significance of M. crassa in the pharmaceutical industry.

Portulaca oleracea polysaccharides reduce serum lipid levels in aging rats by modulating intestinal microbiota and metabolites

Metabolic diseases characterized by dyslipidemia are common health problems for elderly populations. Dietary fiber intake is inversely associated with the risk of dyslipidemia. This study investigated the effects of Portulaca oleracea polysaccharide (POP) on the intestinal microbiota and its metabolites in aging rats using 16S rRNA sequencing and metabolomics techniques. Our results showed that POPs reduced the ratio of Firmicutes/Bacteroidetes (F/B), relative abundance of Fusobacteria, and levels of triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), alanine aminotransferase (ALT), and gamma-glutamyl transferase (γ-GT) in the serum of aging rats. POP supplementation also reduced 5beta-cholestane-3alpha,7alpha,12alpha,25-tetrol, and vaccenic acid concentrations in lipids and lipoid-like molecules, while soyasapogenol E and monoacylglycerol (MG) (24:0/0:0/0:0) levels increased. This study demonstrated that POP’s beneficial effects on lipid levels in aging rats might be partially attributable to the modification of gut microbiota and related metabolites.

Isoliquiritigenin Attenuates Adipose Tissue Inflammation and Metabolic Syndrome by Modifying Gut Bacteria Composition in Mice

SCOPE

Isoliquiritigenin (ILG) has been reported to attenuate adipose tissue inflammation and metabolic disorder; however, the underlying mechanisms remain to be elucidated. The aim of this study is to elucidate whether ILG shows the anti-inflammatory and antimetabolic syndrome effects through gut microbiota modification.

METHODS AND RESULTS

Mice are fed a high-fat diet (HFD) with or without ILG for up to 12 weeks. The effect of ILG on body weight, blood glucose level, adipose tissue inflammation, gut barrier function, and gut microbiota composition are investigated. ILG supplementation alleviates HFD-induced obesity, glucose tolerance, and insulin resistance and suppresses inflammatory gene expression in epididymal white adipose tissue (eWAT). Moreover, ILG supplementation modifies gut bacterial composition by increasing the abundance of antimetabolic disease-associated species (e.g., Parabacteroides goldsteinii and Akkemansia muciniphila) and up-regulated genes associated with gut barrier function. Fecal microbiome transplantation (FMT) from ILG-fed donors counteract HFD-induced body and eWAT weight changes, inflammation-related gene expression, glucose tolerance, and insulin resistance, thereby suggesting that ILG-responsive gut bacteria exerts anti-inflammatory and antimetabolic syndrome effects.

CONCLUSION

Alterations in gut bacteria underly the beneficial effects of ILG against adipose tissue inflammation and metabolic disorders. ILG may be a promising prebiotic for the prevention and treatment of metabolic syndrome.

Obesity I: Overview and molecular and biochemical mechanisms

Obesity is a chronic, relapsing condition characterized by excess body fat. Its prevalence has increased globally since the 1970s, and the number of obese and overweight people is now greater than those underweight. Obesity is a multifactorial condition, and as such, many components contribute to its development and pathogenesis. This is the first of three companion reviews that consider obesity. This review focuses on the genetics, viruses, insulin resistance, inflammation, gut microbiome, and circadian rhythms that promote obesity, along with hormones, growth factors, and organs and tissues that control its development. It shows that the regulation of energy balance (intake vs. expenditure) relies on the interplay of a variety of hormones from adipose tissue, gastrointestinal tract, pancreas, liver, and brain. It details how integrating central neurotransmitters and peripheral metabolic signals (e.g., leptin, insulin, ghrelin, peptide YY_3-36) is essential for controlling energy homeostasis and feeding behavior. It describes the distinct types of adipocytes and how fat cell development is controlled by hormones and growth factors acting via a variety of receptors, including peroxisome proliferator-activated receptor-gamma, retinoid X, insulin, estrogen, androgen, glucocorticoid, thyroid hormone, liver X, constitutive androstane, pregnane X, farnesoid, and aryl hydrocarbon receptors. Finally, it demonstrates that obesity likely has origins in utero. Understanding these biochemical drivers of adiposity and metabolic dysfunction throughout the life cycle lends plausibility and credence to the "obesogen hypothesis" (i.e., the importance of environmental chemicals that disrupt these receptors to promote adiposity or alter metabolism), elucidated more fully in the two companion reviews.

The Impact of Host Genotype, Intestinal Sites and Probiotics Supplementation on the Gut Microbiota Composition and Diversity in Sheep

Three sampling strategies with a 16s rRNA high-throughput sequencing and gene expression assay (by RT-PCR) were designed, to better understand the host and probiotics effect on gut microbiota in sheep. Sampling: (1) colon contents and back-fat tissues from small-tailed Han sheep (SHS), big-tailed Hulun Buir sheep (BHBS), and short-tailed Steppe sheep (SHBS) (n = 12, 14, 12); (2) jejunum, cecum and colon contents, and feces from Tan sheep (TS, n = 6); (3) feces from TS at 4 time points (nonfeeding, 30 and 60 feeding days, and stop feeding 30 days) with probiotics supplementation (n = 7). The results indicated SHS had the highest Firmicutes abundance, the thinnest back-fat, and the lowest expression of C/EBPβ, C/EBPδ, ATGL, CFD, and SREBP1. Some bacteria orders and families could be potential biomarkers for sheep breeds with a distinct distribution of bacterial abundance, implying the host genotype is predominant in shaping unique microbiota under a shared environment. The microbiota diversity and Bifidobacterial populations significantly changed after 60 days of feeding but restored to its initial state, with mostly colonies, after 30 days ceased. The microbiota composition was greatly different between the small and large intestines, but somewhat different between the large intestine and feces; feces may be reliable for studying large intestinal microbiota in ruminants.

Improvement of Metabolic Syndrome in High-Fat Diet-Induced Mice by Yeast β-Glucan Is Linked to Inhibited Proliferation of Lactobacillus and Lactococcus in Gut Microbiota

There is growing evidence that prevention of metabolic syndrome (MS) by dietary fibers is intricately linked to gut microbiota. In the present work, the mice were fed a high-fat diet (HFD) and orally treated with yeast β-glucan to further examine the effects of β-glucan on MS and gut microbiota and the potential relationship between gut microbiota and its activity. After intervention for 10 weeks, it was found that the treatment of yeast β-glucan could significantly improve the HFD-induced MS. Furthermore, pro-inflammatory cytokines in plasma including IL-6 and IL-1β were decreased. Yeast β-glucan could regulate the diversity and composition of HFD-induced gut microbiota. Moreover, the relative abundances of Lactobacillus and Lactococcus, having significant positive correlation with metabolic changes, were decreased by β-glucan, which might play a critical role in attenuation of MS. Our findings suggest that yeast β-glucan shows promising application as a prebiotic for preventing MS and regulating gut microbiota.