The present invention relates to the treatment of nutritional liver diseases or metabolic syndrome. In this study, the inventors aimed to identify bacteria through lactic acid bacteria (LAB), such as lactobacillus or bifidobacteria described for their safety used in humans. Up to now, the LAB strains used as probiotics are previously identified for their protective effect on the gut barrier (46). In this study, they isolated LAB strains in patients with excessive and chronic alcohol consumption (AUD, alcohol use disorder), showing an absence of advanced liver injury. Then, they focused our findings on LAB strains able to better counteract the harmful effect of enterobacteria isolated from a patient with a severe alcoholic disease. Furthermore, they demonstrated that four bacterial strains specifically improve in vitro gut barrier and/or liver injury both in ALD and MAFLD and also metabolic syndrome in MAFLD, in rodent models. Thus, the present invention relates to specific bacteria and their use in the treatment of nutritional liver diseases or metabolic syndrome.