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World J Gastrointest Pathophysiol. May 22, 2022; 13(3): 59-72
Published online May 22, 2022. doi: 10.4291/wjgp.v13.i3.59
Gut microbiome: Linking together obesity, bariatric surgery and associated clinical outcomes under a single focus
Konstantinos Georgiou, Nikolay A Belev, Tilemachos Koutouratsas, Hector Katifelis, Maria Gazouli
Konstantinos Georgiou, The First Propaedeutic Surgical Unit, Hippocrateion Athens General Hospital, Medical School, National and Kapodistrian University of Athens, Athens 11527, Greece
Nikolay A Belev, Medical Simulation Training Center, Research Institute of Medical University of Plovdiv, and UMPHAT “Eurohospital”, Medical University of Plovdiv, Plovdiv 4002, Bulgaria
Tilemachos Koutouratsas, Hector Katifelis, Maria Gazouli, Basic Medical Sciences, Medical School, National and Kapodistrian University of Athens, Athens 11527, Greece
Author contributions: Georgiou K, Koutouratsas K, and Katifelis H wrote the original draft, Gazouli M, and Belev NA edited and reviewed the final version of the manuscript; all authors have read and agreed to the published version of the manuscript.
Conflict-of-interest statement: Authors declare no conflict of interests for this article.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Maria Gazouli, PhD, Professor, Basic Medical Sciences, Medical School, National and Kapodistrian University of Athens, Michalakopoulou 176, Athens 11527, Greece. mgazouli@med.uoa.gr
Received: November 10, 2021
Peer-review started: November 10, 2021
First decision: December 12, 2021
Revised: December 21, 2021
Accepted: March 25, 2022
Article in press: March 25, 2022
Published online: May 22, 2022
Processing time: 189 Days and 1.2 Hours
Abstract

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.

Keywords: Bariatric surgery; Obesity; Gut microbiota; Micronutrient deficiency; Probiotics

Core Tip: Obesity represents a major cause of morbidity and mortality globally. Current knowledge suggests a connection between gut microbiota characteristics and obesity, while bariatric surgery has been shown to promote a healthier microbiota composition. However, the exact effects of these procedures remain unclear. In general, an increase in members of the phylum Bacteroidetes and Proteobacteria, and a decrease in members of the phylum Firmicutes is a common finding. This field of research can also inform clinicians’ predictions of outcomes before and after bariatric surgery through analysis of patterns in gut microbiota.