Purpose: Numerous studies have investigated the effects of widely used probiotics, which are regularly consumed by healthy individuals. However, a comprehensive summary of these effects is still lacking. One of the presumed benefits of probiotic consumption is supporting the intestinal barrier function by reducing permeability. Zonulin is a protein produced by intestinal and liver cells, and its elevated levels in the blood are associated with increased intestinal permeability. Materials/Methods:We conducted a systematic search on 12 April 2024, in the MEDLINE, Embase, and Cochrane databases using a predefined search strategy registered in PROSPERO (CRD42022286137). A total of 9,217 articles were screened by two independent researchers. Data from 307 subjects across five studies were included in the meta-analysis of changes in blood zonulin concentration. Due to differences in measurement techniques, the standardized mean difference (SMD) was chosen as the effect measure. A random-effects model was applied using the inverse variance method to estimate SMD with confidence intervals (CI), considering the expected heterogeneity. Results: The quantitative synthesis of the data indicated no significant difference in blood zonulin levels between the probiotic and control groups (SMD 5 (-)0.01; 95% CI: [-0.39; 0.37], P 5 0.95). Conclusions: Our findings do not support the hypothesis that probiotic supplementation affects blood zonulin levels, and thus, the impact on intestinal barrier integrity was not confirmed in healthy individuals.  Kulcsszavak: probiotics, healthy volunteers, intestinal barrier function, meta-analysis