Bariatric Surgery's Gut Microbiota–Epigenome Axis Unveiled as Key to Sustained Metabolic Improvement

The global obesity epidemic fuels rising rates of type 2 diabetes (T2DM) and metabolic dysfunction-associated steatohepatitis (MASH). While GLP-1 receptor agonists offer significant advances, they often lack the magnitude and durability of weight loss achieved by metabolic and bariatric surgery (BS). Understanding the sustained efficacy of BS beyond caloric restriction is crucial. This review explores the gut microbiota–epigenome axis as a key mechanistic gap, investigating how microbial shifts influence host gene expression to drive metabolic improvements.

This comprehensive review systematically synthesized existing literature to elucidate the intricate interplay between bariatric surgery, the gut microbiota, and host epigenetic modifications. The authors focused on identifying mechanistic insights into how surgical interventions lead to profound and sustained metabolic improvements. The review explored studies detailing changes in microbial composition, metabolite production, and their subsequent impact on host gene expression, DNA methylation, and histone modifications in metabolically active tissues. The aim was to bridge the understanding of microbial-epigenetic crosstalk in the context of BS outcomes and identify potential therapeutic perspectives.

The review highlights that bariatric surgery profoundly reshapes the gut microbial ecosystem, leading to significant shifts in bacterial diversity and metabolic output. These microbial alterations, in turn, are shown to influence host epigenetics, including DNA methylation and histone modifications, in tissues critical for metabolism like the liver, adipose tissue, and pancreas. Specific microbial metabolites, such as short-chain fatty acids (SCFAs), are identified as key mediators, impacting host gene expression related to glucose homeostasis, lipid metabolism, and inflammation. > The synthesis reveals a robust gut microbiota–epigenome axis as a central mechanism driving the sustained metabolic benefits of bariatric surgery, offering a deeper understanding beyond simple caloric restriction. Furthermore, the review discusses how these epigenetic changes contribute to improved insulin sensitivity, reduced hepatic steatosis, and long-term weight maintenance. The authors also identify how the gut-brain axis is modulated through these epigenetic pathways, influencing appetite regulation and energy expenditure post-surgery. This integrated understanding provides a foundation for future targeted interventions.