The gut microbiota's role in bulimia nervosa and binge eating disorder: etiological insights and therapeutic implications from a scoping review

This scoping review synthesizes emerging evidence on the relationship between gut microbiota and eating disorders (EDs), particularly bulimia nervosa (BN) and binge eating disorder (BED). An electronic search was conducted in the PubMed/MEDLINE and Web of Science databases, spanning from their inception until December 2023. From an initial pool of 166 records, 14 articles were included and qualitatively synthesized. Two overarching themes emerged. The first focuses on etiological hypotheses, pointing to autoimmunity and psychoneuroendocrinoimmunological mechanisms as potential mediators in the association between ED pathophysiology and the gut microbiota. Significant findings include the identification of elevated levels of bacterial caseinolytic protease B protein in patients, correlating with symptom severity and specific autoantibodies. Furthermore, studies indicate that gut microbiota proteins might trigger autoantibody production. Distinct microbial profiles are associated with different ED subtypes and behaviors. The second theme examines the clinical implications of this link. Human trials demonstrate the potential of probiotic interventions in improving eating-related clinical outcomes post-bariatric surgery. Murine models also demonstrate the role of gut microbiota in controlling compulsive overeating, with probiotic interventions proving effective in reducing binge eating and anxiety-like behaviors. In conclusion, this review summarizes current research and highlights the interactions among the gut microbiota, immune system, and hormonal regulation in the development and progression of BN and BED. It also highlights the potential for ongoing interdisciplinary research to identify possible underlying mechanisms and reliable biomarkers, with the ultimate goal of developing targeted therapeutic interventions for BN and BED.