Oral Probiotic Supplementation Improves Skin Aging Biomarkers: An 8-Week Double-Blind, Randomized, Placebo-Controlled Trial

Background: Skin aging is influenced by intrinsic and extrinsic factors, and growing evidence suggests that nutritional interventions, particularly probiotics, may modulate key biological pathways involved in skin barrier function, hydration, and oxidative stress through the gut–skin axis. Methods: In this randomized, double-blind, placebo-controlled clinical trial, 66 adults received a probiotic formulation containing Lacticaseibacillus rhamnosus LRH020, Lactiplantibacillus plantarum PBS067, and Limosilactobacillus reuteri PBS072 for 56 days, followed by a 28-day follow-up. Skin structure, function, and oxidative status were assessed using 3D profilometry, high-frequency ultrasound, corneometry, transepidermal water loss (TEWL), FRAP assay, and expert clinical scoring. Results: Compared with placebo, the probiotic group showed significant improvements in wrinkle depth (−15.0% at T56), and roughness (−6.1% at T56). Moreover, other skin parameters were significantly enhanced by the end of treatment, including greater skin density, hydration, and antioxidant capacity, alongside a reduction in TEWL. Improvements persisted at follow-up, suggesting a durable, lasting benefit of the probiotic formulation beyond the treatment period. Conclusions: These findings support the role of targeted probiotic supplementation as a promising strategy to improve structural, functional, and oxidative markers of skin aging.