The trials included in our review showed that the use of probiotics, prebiotics and synbiotics were related to reduction in BMI, total fat percentage, total cholesterol, triglycerides, fasting insulin, LPS, HOMA, TNF-α, IL-6, liver injury (AST, ALT, liver stiffness, fibrosis index, intracellular lipids, NAFLD and NASH scores), and Clostridia and Erysipelotrichia classes. This evidence concerns the gene GPT and metabolic dysfunction-associated steatotic liver disease.