Gut Microbiota, Obesity and Bariatric Surgery: Current Knowledge and Future Perspectives

Brazilian guide to nutrition in bariatric and metabolic surgery

PURPOSE

Brazilian nutrition recommendations for bariatric and metabolic surgery aim to provide knowledge, based on scientific evidence, on nutritional practices related to different surgical techniques in the surgical treatment of obesity and metabolic diseases.

MATERIALS AND METHODS

A systematic literature search was carried out with the appropriate MeSH terms using Medline/Pubmed/LiLACS and the Cochrane database, with the established criteria being based on the inclusion of articles according to the degree of recommendation and strength of evidence of the Classification of Recommendations, Evaluation, Development, and Evaluation System (GRADE).

RESULTS

The recommendations that make up this guide were gathered to assist in the individualized clinical practice of nutritionists in the nutritional management of patients with obesity, including nutritional management in the intragastric balloon; pre and postoperative nutritional treatment and supplementation in bariatric and metabolic surgeries (adolescents, adults, elderly, pregnant women, and vegetarians); hypoglycemia and reactive hyperinsulinemia; and recurrence of obesity, gut microbiota, and inflammatory bowel diseases.

CONCLUSION

We believe that this guide of recommendations will play a decisive role in the clinical practice of nutritionists who work in bariatric and metabolic surgery, with its implementation in health services, thus promoting quality and safety in the treatment of patients with obesity. The concept of precision nutrition is expected to change the way we understand and treat these patients.

Bacteria with potential: Improving outcomes through probiotic use following Roux-en-Y gastric bypass

Obesity impairs the gastrointestinal microbiome (GM) and may promote micronutrient deficiencies. Bariatric surgery (BS), the most efficacious treatment for severe obesity, produces sustained weight loss and improvements in obesity-related comorbidities, but might not fully restore microbial balance. Moreover, BS may result in deleterious consequences that affect weight loss and further intensify post-operative micronutrient deficiencies. To date, the use of probiotics appears to be associated with greater weight loss in bariatric patients, improved vitamin synthesis and availability, and decreased instances of small intestinal bacterial overgrowth. Thus, manipulation of the GM through probiotics represents a promising therapeutic approach in bariatric patients. This review aims to highlight the benefits of using probiotics in bariatric surgical patients by addressing the impact of probiotics on the GM, how BS impacts the microbial environment, associations between gastrointestinal dysbiosis and negative health outcomes, how BS contributes to dysbiosis, and how probiotics may prove efficacious in treating patients who undergo Roux-en-Y gastric bypass (RYGB). Based on currently available data, the role of microbial manipulation post-RYGB through probiotics has shown great potential, but a further clinical investigation is warranted to better understand their efficacy.

Risk-Benefit Balance Associated With Obstetric, Neonatal, and Child Outcomes After Metabolic and Bariatric Surgery

Importance

Metabolic and bariatric surgery (MBS) is the most efficient therapeutic option for severe obesity. Most patients who undergo MBS are women of childbearing age. Data in the scientific literature are generally of a low quality due to a lack of well-controlled prospective trials regarding obstetric, neonatal, and child outcomes.

Objective

To assess the risk-benefit balance associated with MBS around obstetric, neonatal, and child outcomes.

Design, Setting, and Participants

The study included 53 813 women on the French nationwide database who underwent an MBS procedure and delivered a child between January 2012 and December 2018. Each women was their own control by comparing pregnancies before and after MBS.

Exposures

The women included were exposed to either gastric bypass or sleeve gastrectomy.

Main Outcomes and Measures

The study team first compared prematurity and birth weights in neonates born before and after maternal MBS with each other. Then they compared the frequencies of all pregnancy and child diagnoses in the first 2 years of life before and after maternal MBS with each other.

Results

A total of 53 813 women (median [IQR] age at surgery, 30 [26-35] years) were included, among 3686 women who had 1 pregnancy both before and after MBS. The study team found a significant increase in the small-for-gestational-age neonate rate after MBS (+4.4%) and a significant decrease in the large-for-gestational-age neonate rate (-12.6%). The study team highlighted that compared with pre-MBS births, after MBS births had fewer occurrences of gestational hypertension (odds ratio [OR], 0.16; 95% CI, 0.10-0.23) and gestational diabetes for the mother (OR, 0.39; 95% CI, 0.34-0.45), as well as fewer birth injuries to the skeleton (OR, 0.27; 95% CI, 0.11-0.60), febrile convulsions (OR, 0.39; 95% CI, 0.21-0.67), viral intestinal infections (OR, 0.56; 95% CI, 0.43-0.71), or carbohydrate metabolism disorders in newborns (OR, 0.54; 95% CI 0.46-0.63), but an elevated respiratory failure rate (OR, 2.42; 95% CI, 1.76-3.36) associated with bronchiolitis.

Conclusions and Relevance

The risk-benefit balance associated with MBS is highly favorable for pregnancies and newborns but may cause an increased risk of respiratory failure associated with bronchiolitis. Further studies are needed to better assess the middle- and long-term benefits and risks associated with MBS.

Analysis of the Relationship between Gut Flora Levels in Childhood Obese Population and Normal Healthy Population Based on Machine Learning

Aims

To explore the study of the relationship between the level of gut flora in childhood obese people and normal healthy people based on the analysis of machine learning.

Materials and Methods

The stools of 54 normal weight, 53 overweight, and 59 obese children from May 2021 to May 2022 were selected. And DNA was extracted, and primers specific for the four bacteria were designed according to the specificity of the four bacteria to the 16 S rDNA gene sequences of the bacteria to be tested, and real-time fluorescence quantitative PCR reactions were performed to compare whether there was any difference in the number of the four bacteria between the three groups. Results. The results of agarose gel electrophoresis showed that the PCR amplification products of all four target bacteria showed clear bands at the corresponding positions, and no nonspecific bands appeared. When compared with the marker, the size matched with the target fragment, indicating good primer specificity. The comparison between normal body recombinant, super recombinant, and obese groups was statistically significant (P < 0.05) for rectal eubacteria, polymorphic anaplasma, bifidobacteria spp., and lactobacilli. The median number of bifidobacteria in the three groups was significantly higher than the median number of rectal eubacteria, polymorphomycetes, and lactobacilli. The difference in comparison was statistically significant (P < 0.05). Stratified analysis of children's age revealed that normal body composition of Lactobacillus decreased with increasing age, and the difference was statistically significant (P < 0.05).

Conclusion

An increase in rectal eubacteria and a decrease in polymorphomycetes, bifidobacteria spp., and lactobacilli may be associated with the development of obesity. The numbers of rectal eubacteria, polymorphic methanobacteria, bifidobacteria spp., and lactobacilli in the intestine of normal weight and obese children were less affected by sex and age.

Gut microbiota and obesity

Worldwide, adults and childhood obesity are increasing alarmingly, being a major health problem. Obesity is correlated with an increased incidence of various systemic diseases including cancer, heart diseases, and diabetes mellitus type 2. Risk factors for obesity are dysbiosis, genetic, socioeconomic, behavioural and environmental. The gut microbiota has beneficial effects on human health, like host immune system stimulation, being influenced by pH, or nutrient intake. Studies performed on humans and animal models reported differences regarding microbiota at lean and obese individuals. The consumption of probiotics and prebiotics may balance the microbiota with positive effects in obesity. The main aim of this review is to reveal the interaction between dysbiosis and obesity

Gut microbiome: Linking together obesity, bariatric surgery and associated clinical outcomes under a single focus

Obesity is increasingly prevalent in the post-industrial era, with increased mortality rates. The gut microbiota has a central role in immunological, nutritional and metabolism mediated functions, and due to its multiplexity, it is considered an independent organ. Modern high-throughput sequencing techniques have allowed phylogenetic exploration and quantitative analyses of gut microbiome and improved our current understanding of the gut microbiota in health and disease. Its role in obesity and its changes following bariatric surgery have been highlighted in several studies. According to current literature, obesity is linked to a particular microbiota profile that grants the host an augmented potential for calorie release, while limited diversity of gut microbiome has also been observed. Moreover, bariatric surgery procedures represent effective interventions for sustained weight loss and restore a healthier microbiota, contributing to the observed fat mass reduction and lean mass increase. However, newer evidence has shown that gut microbiota is only partially recovered following bariatric surgery. Moreover, several targets including FGF15/19 (a gut-derived peptide), could be responsible for the favorable metabolic changes of bariatric surgery. More randomized controlled trials and larger prospective studies that include well-defined cohorts are required to better identify associations between gut microbiota, obesity, and bariatric surgery.

Metabolite Signature of Physical Activity and the Risk of Type 2 Diabetes in 7271 Men

Large population-based studies investigating the association of physical activity (PA) with the metabolite signature contribute significantly to the understanding of the effects of PA on metabolic pathways associated with the risk of type 2 diabetes. Our study included 8749 Finnish men without diabetes at baseline recruited from the Metabolic Syndrome in Men (METSIM) cohort. We used a questionnaire to measure leisure-time PA. Metabolites were measured in 7271 men as a part of Metabolon’s untargeted Discovery HD4 platform using ultrahigh-performance liquid chromatography–tandem mass spectrometry. We found 198 metabolites significantly associated with PA. Several of these metabolites were novel including especially steroids, amino acids, imidazoles, carboxylic acids, and hydroxy acids. Increased PA was significantly associated with high levels of choline plasmalogens, lysophosphatidylcholines, polyunsaturated fatty acids, carotenoids, long chain acylcarnitines, imidazoles, bilirubins, aryl sulfates, hydroxy acids, indolepropionate, and indolelactate. Several of these metabolites have been previously associated with a decreased risk of type 2 diabetes and with a healthy diet. Our population-based study shows that the metabolite signature of increased PA includes multiple metabolic pathways and is associated with better adherence to a healthy lifestyle.

Progress in treatment of type 2 diabetes by bariatric surgery

The incidence of type 2 diabetes (T2D) is increasing at an alarming rate worldwide. Bariatric surgical procedures, such as the vertical sleeve gastrectomy and Roux-en-Y gastric bypass, are the most efficient approaches to obtain substantial and durable remission of T2D. The benefits of bariatric surgery are realized through the consequent increased satiety and alterations in gastrointestinal hormones, bile acids, and the intestinal microbiota. A comprehensive understanding of the mechanisms by which various bariatric surgical procedures exert their benefits on T2D could contribute to the design of better non-surgical treatments for T2D. In this review, we describe the classification and evolution of bariatric surgery and explore the multiple mechanisms underlying the effect of bariatric surgery on insulin resistance. Based upon our summarization of the current knowledge on the underlying mechanisms, we speculate that the gut might act as a new target for improving T2D. Our ultimate goal with this review is to provide a better understanding of T2D pathophysiology in order to support development of T2D treatments that are less invasive and more scalable.

Effects of cat ownership on the gut microbiota of owners

Pet ownership is an essential environmental exposure that might influence the health of the owner. This study’s primary objectives were to explore the effects of cat ownership on the gut microbial diversity and composition of owners. Raw data from the American Gut Project were obtained from the SRA database. A total of 214 Caucasian individuals (111 female) with cats and 214 individuals (111 female) without cats were used in the following analysis. OTU number showed significant alteration in the Cat group and Female_cat group, compared with that of the no cat (NC) group and Female_ NC group, respectively. Compared with the NC group, the microbial phylum Proteobacteria was significantly decreased in the Cat group. The microbial families Alcaligenaceae and Pasteurellaceae were significantly reduced, while Enterobacteriaceae and Pseudomonadaceae were significantly increased in the Cat group. Fifty metabolic pathways were predicted to be significantly changed in the Cat group. Twenty-one and 13 metabolic pathways were predicted to be significantly changed in the female_cat and male_cat groups, respectively. Moreover, the microbial phylum Cyanobacteria was significantly decreased, while the families Alcaligenaceae, Pseudomonadaceae and Enterobacteriaceae were significantly changed in the normal weight cat group. In addition, 41 and 7 metabolic pathways were predicted to be significantly changed in the normal-weight cat and overweight cat groups, respectively. Therefore, this study demonstrated that cat ownership could influence owners’ gut microbiota composition and function, especially in the female group and normal-weight group.

Relationship between bariatric surgery outcomes and the preoperative gastrointestinal microbiota: a cohort study

BACKGROUND

The composition of the gastrointestinal microbiota is associated with obesity. We hypothesized that the gut microbiota influences the outcomes of bariatric surgery.

OBJECTIVES

We aimed to analyze using oral swabs and stool samples the microbiota of patients with morbid obesity who were undergoing laparoscopic sleeve gastrectomy (SG).

SETTING

A university hospital in Poland.

METHODS

This prospective cohort study was conducted between November 2018 and June 2019. Participants underwent SG or no surgery (controls). Results were then analyzed as a group 1 (surgical participants who achieved a percentage of excess weight loss [%EWL] >50%), group 2 (surgical participants who achieved a %EWL <50%), and group 3 (nonsurgical controls). %EWL was measured 6 months following surgery. Before surgery, oral swabs were obtained and stool samples were provided. The endpoint was the composition of the gut microbiota.

RESULTS

Group 1 comprised 19 participants, group 2 comprised 11 participants, and group 3 comprised 16 participants. No participants were lost to follow-up during the study. Participants in group 1 had an oral microbiota that was enriched in the phyla Proteobacteria, and Bacteroidetes. Their intestinal microbiota was enriched in the Proteobacteria. In contrast, the oral microbiota of group 2 was enriched in the Actinobacteria and the intestinal microbiota was enriched in the phyla Bacteroidetes and Firmicutes.

CONCLUSIONS

The compositions of the microbiota of the oral cavity and large intestine are related to the weight loss achieved following SG.

A Spectrum of Topics for 2019: Advances in Neuroinflammation, Oxidative Stress, Obesity, Diabetes Mellitus, Cardiovascular Disease, Autism, Exosomes, and Central Nervous System Diseases

Advances in various fields were discussed in the reviews and original research articles published in 2019 in Current Pharmaceutical Design. Here, I review some of the major highlights for selected areas. A better understanding of disease mechanisms was a prominent recurrent theme and new therapeutic targets based on those mechanisms are highlighted here. Inflammation and oxidative stress are major features of many diseases, therefore, interventions to address these processes are reviewed. Although repurposing of old drugs occurred in several fields, drug targeting and drug delivery, especially of nanoparticles, also continues to be a major area of interest.

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.

Bariatric Surgery in Obesity: Effects on Gut Microbiota and Micronutrient Status

Obesity is associated with reduced gut microbial diversity and a high rate of micronutrient deficiency. Bariatric surgery, the therapy of choice for severe obesity, produces sustained weight loss and improvements in obesity-related comorbidities. Also, it significantly alters the gut microbiota (GM) composition and function, which might have an important impact on the micronutrient status as GM is able to synthesize certain vitamins, such as riboflavin, folate, B12, or vitamin K2. However, recent data have reported that GM is not fully restored after bariatric surgery; therefore, manipulation of GM through probiotics represents a promising therapeutic approach in bariatric patients. In this review, we discuss the latest evidence concerning the relationship between obesity, GM and micronutrients, the impact of bariatric surgery on GM in relation with micronutrients equilibrium, and the importance of the probiotics' supplementation in obese patients submitted to surgical treatment.