INTRODUCTION: Recent research has identified gut microbiota dysbiosis as a potential contributing factor in schizophrenia, leading to growing interest in exploring probiotics as a complementary approach to traditional antipsychotic treatments. This study aims to systematically evaluate the current evidence on the efficacy of probiotics in improving clinical symptoms of schizophrenia, offering a novel perspective into their potential role as an adjunctive strategy. METHODS: A systematic search was conducted to review randomized clinical trials, adhering to the PRISMA guidelines. A meta-analysis was also performed to assess the primary outcome, which was the impact of probiotic supplementation on clinical symptoms measured by the Positive and Negative Syndrome Scale (PANSS). RESULTS: Of the 76 studies initially identified, 5 were finally included. Regarding the symptomatology measured through the PANSS total score, the average effect was significant after the probiotic supplementation (standardized mean difference [SMD] = -0.608, (95% CI -1.314
-0.047), p = .035. CONCLUSION: The synthesis of available data suggests that probiotic supplementation may effectively reduce clinical symptoms in schizophrenia. However, the limited number of studies prevents the formation of robust conclusions. Further clinical trials with more rigorous experimental designs are necessary before making definitive recommendations.