Understanding the importance of the gut microbiota (GM) in non-alcoholic fatty liver disease (NAFLD) has raised the hope for therapeutic microbes. We have shown that high hepatic fat content associated with low abundance of Faecalibacterium prausnitzii in humans and, further, the administration of F. prausnitzii prevented NAFLD in mice. Here, we aimed at targeting F. prausnitzii by prebiotic xylo-oligosaccharides (XOS) to treat NAFLD. First, the effect of XOS on F. prausnitzii growth was assessed in vitro. Then, XOS was supplemented or not with high (HFD, 60% of energy from fat) or low (LFD) fat diet for 12 weeks in Wistar rats (n = 10/group). XOS increased F. prausnitzii growth, having only a minor impact on the GM composition. When supplemented with HFD, XOS ameliorated hepatic steatosis. The underlying mechanisms involved enhanced hepatic β-oxidation and mitochondrial respiration. Nuclear magnetic resonance (1H-NMR) analysis of cecal metabolites showed that, compared to the HFD, the LFD group had a healthier cecal short-chain fatty acid profile and on the HFD, XOS reduced cecal isovalerate and tyrosine, metabolites previously linked to NAFLD. Cecal branched-chain fatty acids associated positively and butyrate negatively with hepatic triglycerides. In conclusion, XOS supplementation can ameliorate NAFLD by improving hepatic oxidative metabolism and affecting GM.

Because the high prevalence of nonalcoholic fatty liver disease sets diagnostic challenges to health care, identification of new biomarkers of the disease that in the future could have potential utility as diagnostic biomarkers of high liver fat content is important. Our results show that increased amino acid degradation products in the feces may be such biomarkers.

Understanding the importance of gut microbiota (GM) in non-alcoholic fatty liver disease (NAFLD) has raised the hope for therapeutic microbes. We have shown that high hepatic fat associated with low abundance of Faecalibacterium prausnitzii in humans and further, administration of F. prausnitzii prevented NAFLD in mice. Here, we aimed to target F. prausnitzii by prebiotic xylo-oligosaccharides (XOS) to treat NAFLD. First, the effect of XOS on F. prausnitzii growth was assessed in vitro. Then, XOS was supplemented or not with high (HFD) or low (LFD) fat-diet for 12-weeks in Wistar rats (n=10/group). XOS increased F. prausnitzii growth having only minor impact on the GM composition. When supplemented with HFD, XOS prevented hepatic steatosis. The underlying mechanisms involved enhanced hepatic β-oxidation and mitochondrial respiration. 1H-NMR analysis of caecal metabolites showed that compared to HFD, LFD group had healthier caecal short-chain fatty acid profile and the combination of HFD and XOS was associated with reduced caecal isovalerate and tyrosine, metabolites previously linked to NAFLD. Caecal branched-chain fatty acids associated positively and butyrate negatively with hepatic triglycerides. In conclusion, our study identifies F. prausnitzii as a possible target to treat NAFLD with XOS. The underlying preventive mechanisms involved improved hepatic oxidative metabolism.