Harnessing probiotics against candidiasis: a systematic review of experimental and mechanistic evidence

Background Candida species are among the most important opportunistic fungal pathogens responsible for superficial mucosal infections and life-threatening invasive candidiasis, particularly in immunocompromised individuals. The increasing prevalence of antifungal resistance, biofilm-associated tolerance, and the emergence of multidrug-resistant species such as Candida auris have highlighted the need for alternative or adjunctive therapeutic strategies. Probiotics have emerged as promising microbiome-based interventions owing to their ability to inhibit Candida growth, suppress virulence traits, restore microbial homeostasis, and modulate host immune responses. Methods This systematic review comprehensively evaluated the experimental and mechanistic evidence regarding the anti- Candida activity of probiotics and probiotic-derived products. A systematic literature search was conducted in PubMed, Scopus, and Web of Science for studies published between 1 January 2015 and 5 January 2026 in accordance with PRISMA 2020 guidelines. Studies meeting the predefined eligibility criteria were included in the qualitative synthesis. Results Eighteen studies met the predefined eligibility criteria. Most studies investigated Lactobacillus species, followed by Bifidobacterium , Saccharomyces , and probiotic-derived metabolites or postbiotics, using predominantly in vitro models with limited in vivo evidence. Across studies, probiotics consistently demonstrated anti- Candida activity through inhibition of fungal growth, adhesion, yeast-to-hyphal transition, biofilm formation, and virulence-associated gene expression. Additional mechanisms included the production of antimicrobial metabolites, competitive exclusion, immune modulation, enhancement of epithelial barrier function, and restoration of microbial homeostasis. Emerging evidence also supports the antifungal potential of postbiotics and activity against non-albicans Candida species and Candida auris , although available evidence remains limited. Considerable heterogeneity in probiotic strains, experimental models, methodologies, and outcome measures precluded quantitative meta-analysis. Conclusions Current evidence supports probiotics and postbiotics as promising microbiome-based strategies for reducing Candida pathogenicity; however, the available evidence remains predominantly preclinical. Well-designed clinical studies are required to establish strain-specific efficacy, optimal formulations, dosing strategies, safety, and therapeutic applicability before routine clinical implementation. Systematic review registration https://www.crd.york.ac.uk/prospero/view/CRD420261278363 , identifier CRD420261278363.