Surgery Today · Feb 9, 2026

Impact of laparoscopic sleeve gastrectomy on gut and oral microbiota diversity, weight loss, and the metabolic outcomes

By Umemura A, Sasaki A, Sasaki D et al.

PURPOSE: Metabolic and bariatric surgery (MBS) alters the gut microbiota (GM). Changes in oral microbiota (OM) after MBS have not yet been thoroughly investigated. In this study, we evaluated the changes in GM and OM before and after laparoscopic sleeve gastrectomy (LSG) in patients with severe obesity and investigated the relationship between improvements in GM/OM, weight loss, and the metabolic effects. METHODS: Thirty-seven severely obese patients who underwent LSG were enrolled in this study. We retrieved samples from the feces and oral mucosa from baseline to 1-year after LSG. These samples were subjected to a 16 S rRNA metagenomic analysis using a next-generation sequencer. We evaluated the significant changes in GM/OM and compared the results with clinical outcomes. RESULTS: Regarding OM diversity, g_Actinomyces (p = 0.003), o_Rothia (p = 0.020), and g_Streptococcus (p = 0.004) increased. With regard to GM, g_Slackia (p = 0.039), g_Bacillus (p = 0.030), g_Roseburia (p = 0.027), and g_Faecalibacterium (P = 0.003) increased, the proportion of p_ Firmicutes increased, and p_Bacteroidetes decreased in both groups. Changes in g_Akkermansia did not contribute to GM/OM diversity. The weight loss and remission rates of type 2 diabetes were higher in patients with increased normal oral flora and a recovery of g_Faecalibacterium in GM. CONCLUSIONS: We clarified that the LSG reconstructs GM/OM as weight loss and the metabolic effects are enhanced.

doi.org/10.1007/s00595-026-03241-z PubMed 41661326 Interventions