Detection of Self-Induced Vomiting in Eating Disorders Through Oral Microbiota Profiling

Background Eating disorders (EDs) are severe psychiatric conditions frequently associated with purging behaviors such as self-induced vomiting, which can cause serious medical complications. Saliva is an accessible biofluid reflecting oral and systemic health and may provide biomarkers of purging. This study examined whether salivary microbiota profiles are linked to vomiting frequency in EDs. Methods We conducted a case–control study including 27 women with EDs (24 bulimia nervosa; 3 OSFED–purging subtype) and 27 age and sex matched healthy controls (HC). Saliva was collected one week after admission to the Eating Disorders Unit of Barcelona and analyzed with 16S rRNA sequencing. Diversity indices, core microbiome, differential abundance, and functional predictions (PICRUSt2) were assessed. Results The ED group reported a mean vomiting frequency of 4.3 ± 4.9 episodes per week, a mean BMI of 26.3 ± 6.1 kg/m², and an EDI-2 total score of 122.7 ± 32. Beta diversity significantly differed between ED and HC microbiota (PERMANOVA unweighted p = .044; weighted p = .001). Actinomyces and Bulleidia were enriched in EDs, whereas Veillonella and Oribacterium were depleted. Vomiting frequency correlated positively with Actinomyces, Granulicatella , and Bulleidia , and negatively with Eikenella . Functional analyses indicated shifts in pathways related to secondary metabolite biosynthesis and carbohydrate degradation. Conclusions ED patients engaging in vomiting show distinct salivary microbiota signatures, with specific taxa correlating to purging severity. Saliva-based microbiome profiling may represent a potential novel biomarker, by means of non-invasive tool, for early detection and monitoring of purging behaviors in EDs.