(P40-23-26) Gut Microbiome Profiles in Young Adults With Anorexia Nervosa Compared With Healthy Controls and Individuals With Obesity

Objectives: Anorexia nervosa (AN) is characterized by chronic energy restriction and metabolic disruption. Gut microbiome alterations may contribute to AN via affecting metabolism and gut-brain signaling. Herein we characterized gut microbiome profiles in young adults with AN compared with age- and sex-matched participants with normal weight or obesity. We hypothesized that individuals with AN would show reduced microbial diversity and distinct taxonomic signatures.

Methods: An observational case-control study included 30 adults across three groups: AN (n=10), healthy controls (n=10), and obesity (n=10) (mean age 21.03±4.87 years). Each group included 9 females and 1 male. Participants with AN were recruited through an eating disorder clinic and controls from a university population. Participants completed screening, questionnaires, anthropometrics, 3-day dietary records analyzed with NDSR, and fecal sample collection. Gut microbiome was assessed using 16S rRNA sequencing with qiime2-dada2 bioinformatic pipeline. Group comparisons evaluated alpha-diversity, beta-diversity, and taxonomic relative abundance.

Results: Weight and BMI differed significantly across groups (p < 0.01), lowest in AN (64.83±14.75 kg) and highest in obesity (82.04±7.52 kg). Alpha-diversity (Shannon and Chao1 indices) and beta-diversity (PCoA) did not differ between groups, though beta-diversity showed a trend toward separation between AN and healthy controls (PERMANOVA p=0.128). Most genera were not significantly different. Faecalibacterium and Alistipes showed trends toward group differences (p < 0.1), with lower Faecalibacterium and higher Alistipes in AN. Parabacteroides abundance differed significantly and was higher in AN than normal weight controls (Bonferroni p=0.028). A general linear model adjusting for age and BMI confirmed group status predicted Parabacteroides abundance (F=7.13; p=0.004).

Conclusions: Individuals with AN exhibit increased Parabacteroides abundance independent of BMI, suggesting a microbiome feature associated with eating disorder status. Although overall diversity did not differ, trends in Faecalibacterium and Alistipessuggest potential taxa level alterations that warrant investigation in larger cohorts.

Funding Sources: Florida State University