Targeting the Gut Microbiota with Pro- and Postbiotics: Emerging Strategies against Alopecia.

Alopecia, which encompasses disorders such as androgenetic alopecia, alopecia areata, and telogen effluvium, is a complex condition influenced by genetic, hormonal, immunological, and environmental factors. Recent research has highlighted the importance of the gut-hair axis, whereby gut microbiota and their metabolites impact systemic immunological balance, oxidative stress, and nutritional bioavailability. Dysbiosis is associated with increased inflammation, impaired epithelial barrier function, and altered metabolite synthesis, which contribute to hair follicle shrinkage and a disruption of the hair cycle. Modulating gut microbiota with probiotics, prebiotics, postbiotics, synbiotics, and parabiotics has shown promise in preclinical and early clinical investigations. Probiotic strains, including Lactobacillus and Bifidobacterium, exhibit immunoregulatory, antioxidant, and barrier-enhancing properties. Similarly, postbiotic metabolites, such as short-chain fatty acids, bacteriocins, and exopolysaccharides, have shown anti-inflammatory and cytoprotective activities. Furthermore, nutritional components influence microbial communities to enhance hair health. Although, additional randomized controlled studies are necessary, microbiota-targeted approaches represent an innovative paradigm in alopecia treatment, advancing towards individualized, root-cause-driven therapies.