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

Abstract

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.

Fecal Metabolome and Bacterial Composition in Severe Obesity: Impact of Diet and Bariatric Surgery

“…The dissimilar impact of the two bariatric surgical approaches on gut microbial composition has been exhaustively reviewed, with consistent results [9,[21][22][23][24][25][26][27]. Alpha diversity dynamics appear not to be reproducible across studies; however, beta diversity analyses consistently nd deeper changes for RYGB, including an expansion of the Pseudomonadota (formerly Proteobacteria) phyla [28][29][30][31][32][33].…”

Roux-En-Y Gastric Bypass (RYGB) Surgery during High Liquid Sucrose Diet Leads to Gut Microbiota-Related Systematic Alterations

“…RYGB surgery causes a persistent environmental change of the gut which has been previously associated with a long-lasting impact on the microbiota composition and metabolism [44]. RYGB has also been shown to promote a change in dietary habits and their associated neuronal processes [45]. Bacteroidetes and Proteobacteria such as Escherichia have been reported to actively express the genes necessary for producing the neurotransmitter GABA in human stool [46].…”

Microbiome

“…Numerous studies demonstrate the effects of this treatment strategy geared towards weight loss and controlling obesity had adverse influences on normal gut microflora. 22 The alterations in gut microbiota after Roux-en-Y gastric bypass or sleeve gastrectomy contribute to reducing body weight. 23 This change in gut microbiota can have a negative effect on stable weight loss due to the increased abundance of Gammaproteobacteria.…”