Harnessing Probiotics to Combat Candidiasis: Mechanisms, Evidence, and Future Directions

Candida species are common commensals within the human microbiome but can transition opportunistically to pathogenic states when host-microbe homeostasis is disrupted. Their ability to adhere to mucosa and implanted medical devices, form thick biofilms, and invade epithelial tissues makes candidiasis particularly harmful in immunocompromised and elderly populations. This review examines the reported antifungal activity of common probiotic genera such as Lactobacillus, Bacillus, Bifidobacterium, and Saccharomyces across the oral cavity, gastrointestinal tract, and vaginal tract. The probiotic mechanisms of action, such as competitive exclusion, secretion of antifungal metabolites, and immunomodulation, are explored in detail, and research methodologies are scrutinised to assess the robustness of current evidence. This review compiles evidence from a variety of studies and clinical trials showing certain probiotic strains and formulations have the ability to significantly decrease Candida colonisation and reduce candidiasis symptom prevalence. Although outcomes vary greatly between probiotic strains tested, species of Candida targeted, and specific site of infection, it is clear that selected probiotic species and their secreted substances can have prominent anti-Candida effects and promote tangible clinical improvements. Future directions for the field of probiotic study are suggested, including the roles of prebiotics, postbiotics, and synbiotic formulations to enhance probiotic efficacy against candidiasis.