Significant decrease in Faecalibacterium among gut microbiota in nonalcoholic fatty liver disease: a large BMI- and sex-matched population study

Background Compositional changes of the gut microbiota are known to occur in patients with nonalcoholic fatty liver disease (NAFLD); however, the changes did not corroborate between the studies. We evaluated the gut microbiota between NAFLD and non-NAFLD participants, excluding the influence of obesity and sex in this study involving a large number of participants. Methods In total, 1148 adults participated in the health survey. NAFLD was defined as fatty liver by ultrasonography in the absence of other causes of steatosis. To exclude the influence of obesity and sex, NAFLD participants were matched to non-NAFLD participants based on BMI and sex. The relative abundance of each bacterial taxa in fecal samples was calculated using 16S ribosomal RNA amplification and was compared between NAFLD and non-NAFLD participants. Results There were 205 (23.5%) participants defined as having NAFLD. Before matching, there were significant differences in the relative abundance of more than 1% in two classes, two orders, three families, and three genera including Faecalibacterium between NAFLD and non-NAFLD participants. After matching, 153 matched pairs were obtained. In terms of the relative abundance of more than 1%, the relative abundance of two taxa, including the family Ruminococcaceae and the genus Faecalibacterium , was significantly lower in NAFLD participants than in non-NAFLD participants ( p = 0.016 and p = 0.018). Conclusions The significant decrease in Faecalibacterium is a remarkable characteristic on BMI- and sex-matched analysis in NAFLD participants in a large study population. The decrease in Faecalibacterium is related to the pathogenesis of NAFLD.