A new study in eGastroenterology links gut dysbiosis with severe steatosis in metabolic dysfunction–associated steatotic liver disease (MASLD). In a 61-patient cohort, those with the inflammation-linked Bact2 enterotype developed severe steatosis at lower thresholds. Adding microbiota status to standard clinical tools improved diagnostic accuracy from 80% to 90%, suggesting a path toward earlier detection and personalized care.
MASLD: A Growing Global Burden
Metabolic dysfunction–associated steatotic liver disease (MASLD), formerly termed non-alcoholic fatty liver disease (NAFLD), is now the most common chronic liver disorder worldwide. Affecting nearly 38% of the global population, its prevalence parallels the epidemic of metabolic syndrome (MetS), a cluster of conditions including obesity, insulin resistance, and dyslipidaemia. Excessive fat accumulation in the liver, known as hepatic steatosis, drives disease progression, increases the risk of fibrosis, cirrhosis, and liver cancer.
Early identification of patients at risk of severe steatosis is crucial, yet current clinical tools such as the Fatty Liver Index (FLI) are imperfect. Mounting evidence points to the gut microbiota—disrupted in both MASLD and MetS—as a potential player in improving diagnosis.
Study Design and Key Findings
The new study, led by Professor Sara Vieira-Silva, analysed data from the microDHNA cohort, a cross-sectional study of 61 patients with MetS across different stages of MASLD. Participants underwent liver imaging, clinical evaluation, and gut microbiota profiling.
- Linking Gut Dysbiosis to Severe Steatosis. The study revealed a distinct microbial signature associated with steatosis severity. Patients with more advanced steatosis had: (1) Reduced beneficial commensals, including Akkermansia, known for maintaining gut barrier integrity. (2) Increased opportunistic bacteria, such as Streptococcus. (3) Higher prevalence of the Bacteroides 2 (Bact2) enterotype, a microbial community type previously linked to inflammation and reduced butyrate-producing capacity. Strikingly, Bact2 carriers reached the threshold for severe steatosis at much lower FLI scores than non-carriers (74 vs 101), suggesting that dysbiosis accelerates disease progression.
- Enhancing Diagnosis with Microbiota Profiling. To test whether microbial features could improve clinical diagnosis, the researchers built predictive models incorporating different variables.
- FLI alone: classified severe steatosis with 80% accuracy and an area under the ROC curve (AUC) of 92%.
- Bact2 status alone: showed similar accuracy (80%) but added independent predictive value.
- FLI + Bact2 combined: produced the best model, with 90% accuracy and AUC of 96%—a 10% increase in accuracy compared to FLI alone.
This finding demonstrates that simple microbial community typing can substantially strengthen non-invasive diagnostic tools.
Biological Implications of the Bact2 Enterotype
Beyond diagnostics, the study highlights the biological significance of dysbiosis. The Bact2 enterotype is characterised by reduced butyrate producers, depletion of metabolic diversity, and increased inflammatory potential. Prior research shows that this enterotype impairs glucose metabolism, increases bile acid production, and weakens gut barrier function. Together, these changes may promote systemic inflammation and exacerbate liver fat accumulation. Thus, dysbiosis is not just a biomarker—it may be an active driver of steatosis progression.
Clinical Relevance and Next Steps
The study suggests that profiling a patient's gut microbiota could:
- Enable earlier detection of high-risk MASLD patients
- Support more precise risk stratification
- Open possibilities for microbiota-based therapies, such as dietary interventions or probiotics
The authors caution that larger, longitudinal studies are needed to confirm whether restoring gut microbial balance can slow MASLD progression.
In conclusion, this study provides compelling evidence that gut dysbiosis, particularly the inflammation-linked Bact2 enterotype, is strongly associated with severe hepatic steatosis in MASLD. Incorporating microbiota profiling with established clinical predictors significantly improves diagnostic accuracy.
