Review article: can bugs be drugs? The potential of probiotics and prebiotics as treatment for non‐alcoholic fatty liver disease

Summary Background Non‐alcoholic fatty liver disease (NAFLD) has become the most common chronic liver condition. A major current research effort is ongoing to find potential strategies to treat NAFLD‐non‐alcoholic steatohepatitis (NASH), with special attention to the gut microbiota. Multiple animal studies and pilot clinical trials are assessing different gut microbiota modulating strategies such as faecal microbiota transplantation, antibiotics, probiotics, prebiotics and synbiotics. Aim To review the role of microbiota in NAFLD‐NASH and determine whether pro‐ and prebiotics have potential as treatment Methods Information was obtained from critically reviewing literature on PubMed on targeting the gut microbiota in NAFLD. Search terms included NAFLD, NASH, non‐alcoholic fatty liver disease, steatohepatitis; combined with microbiome, microbiota, gut bacteria, probiotics and prebiotics. Results Animal studies and the first emerging studies in humans show promising results for both the common probiotics Lactobacillus, Bifidobacterium and Streptococci as for short chain fatty acid (SCFA) butyrate‐producing bacteria. Also, prebiotics have positive effects on different mechanisms underlying NAFLD‐NASH. Conclusions The most promising strategies thus far developed to alter the microbiome in NAFLD‐NASH are probiotics and prebiotics. However, pre‐ and probiotic treatment of NAFLD‐NASH is relatively new and still under development. Actual understanding of the involved mechanisms is lacking and changes in the intestinal microbiota composition after treatment are rarely measured. Furthermore, large clinical trials with comparative endpoints are unavailable. Personalised treatment based on metagenomics gut microbiota analysis will probably be part of the future diagnosis and treatment of NAFLD‐NASH.