Gut microbiota and host-derived biomarkers evolve dynamically during nutritional rehabilitation in adolescents with severe anorexia nervosa, supporting their potential role as complementary tools for monitoring biological recovery.
Key Findings
Results
Adolescents with severe anorexia nervosa showed reduced bacterial richness compared with healthy controls at baseline.
Chao1 diversity was significantly lower in AN compared to healthy controls (p = 0.00013)
Shannon and Simpson indices did not differ significantly between groups (p = 0.54 and p = 0.27, respectively)
This indicates reduced species richness but not necessarily reduced evenness in the AN gut microbiome
Study included 26 adolescents with severe AN evaluated at hospital admission (T0)
Results
Microbial community composition differed significantly between adolescents with anorexia nervosa and healthy controls.
Bray-Curtis dissimilarity showed significant group differences (R2 = 0.0724, FDR-adjusted p = 0.001)
Unweighted UniFrac distance also showed significant group differences (R2 = 0.0540, FDR-adjusted p = 0.001)
Both beta-diversity metrics confirmed compositional differences between AN and healthy controls
Gut microbiota composition was assessed by 16S rRNA sequencing
Results
LEfSe analysis identified 19 differentially abundant taxa between anorexia nervosa patients and healthy controls, with distinct enrichment patterns in each group.
Blautia_A_141781, Romboutsia_B, and Clostridium_T were among the strongest discriminators enriched in AN patients
Akkermansia, Phocaeicola_A_858004, and Bacteroides_H were enriched in healthy controls
A total of 19 taxa were identified as differentially abundant by LEfSe analysis
Predicted functional profiling was performed using PICRUSt2 to complement compositional findings
Results
Nutritional rehabilitation over three months was associated with partial microbiota remodeling alongside significant improvements in BMI and heart rate.
Patients were evaluated at hospital admission (T0), after one month (T1), and after three months of inpatient nutritional rehabilitation (T2)
Microbiota remodeling was described as partial, not complete, over the three-month period
BMI and heart rate showed significant improvements during the rehabilitation period
Linear mixed-effects models were used to evaluate longitudinal changes
Results
Several host-derived biomarkers of intestinal barrier integrity and microbial metabolism changed significantly over time during nutritional rehabilitation.
Urinary indican, serotonin, nitric oxide, and serum occludin changed significantly over the three-month rehabilitation period
Bile acids, short-chain fatty acids, IgA, lipopolysaccharide, and haptoglobin remained stable throughout the study period
Both serum and urinary biomarkers of intestinal barrier integrity and microbial metabolism were evaluated longitudinally
Psychometric scores (CDI-2, MASC-2) were also evaluated alongside biological markers
Methods
This study employed a prospective longitudinal design to comprehensively characterize host-microbiota interactions in adolescent anorexia nervosa, a design described as scarce in the pediatric literature.
26 adolescents with severe AN were enrolled in the study
Three time points were assessed: hospital admission (T0), one month (T1), and three months (T2) of inpatient nutritional rehabilitation
Gut microbiota composition was compared with healthy controls (HC) at baseline
The study combined 16S rRNA sequencing, predicted functional profiling (PICRUSt2), serum and urinary biomarkers, routine clinical and biochemical parameters, and psychometric scores
What This Means
This research suggests that teenagers hospitalized with severe anorexia nervosa have measurably different gut bacterial communities compared to healthy peers. Specifically, patients with anorexia had fewer distinct bacterial species (lower richness) and a different overall composition of gut bacteria, with certain bacterial groups like Akkermansia being less common in anorexia patients than in healthy controls. Over three months of inpatient nutritional rehabilitation, the gut microbiome partially shifted back toward a healthier profile, alongside improvements in body weight (BMI) and heart rate.
The study also tracked biological markers in blood and urine that reflect how well the gut lining is functioning and how gut bacteria process various substances. Some of these markers — including urinary indican, serotonin, nitric oxide, and a protein called occludin — changed meaningfully over the three months of treatment, while others like bile acids, short-chain fatty acids, and immune markers remained relatively stable. This suggests that recovery from anorexia involves complex, gradual biological changes in the gut that do not all follow the same timeline.
This research matters because it provides some of the first detailed, time-tracked evidence in adolescents that anorexia nervosa is not just a psychological condition but involves significant changes in gut biology that evolve during treatment. The findings suggest that gut microbiota composition and related biological markers could potentially serve as tools to monitor how well a patient is recovering on a biological level, complementing the psychological and nutritional assessments already used in clinical care.
Gargiullo L, Del Chierico F, Marchili M, Irrera M, Pretelli I, Scanu M, et al.. (2026). Host-Microbiota Interactions in Adolescents with Severe Anorexia Nervosa: Linking Gut Dysbiosis, Intestinal Barrier Function and Microbial Metabolism.. Nutrients. https://doi.org/10.3390/nu18193136