Efficacy of probiotics in hair growth and dandruff control: A systematic review and meta-analysis.

BACKGROUND: Probiotics are intellectually rewarding for the discovery of their potential as a source of functional food. Investigating the economic and beauty sector dynamics, this study conducted a comprehensive review of scholarly articles to evaluate the capacity of probiotics to promote hair growth and manage dandruff.

METHODS: We used the PRISMA 2020 with Embase, Pubmed, ClinicalTrials.gov, Scopus, and ICTRP databases to investigate studies till May 2023. Meta-analyses utilizing the random effects model were used with odds ratios (OR) and standardized mean differences (SMD).

RESULT: Meta-analysis comprised eight randomized clinical trials and preclinical studies. Hair growth analysis found a non-significant improvement in hair count (SMD = 0.32, 95 % CI -0.10 to 0.75) and a significant effect on thickness (SMD = 0.92, 95 % CI 0.47 to 1.36). In preclinical studies, probiotics significantly induced hair follicle count (SMD = 3.24, 95 % CI 0.65 to 5.82) and skin thickness (SMD = 2.32, 95 % CI 0.47 to 4.17). VEGF levels increased significantly (SMD = 2.97, 95 % CI 0.80 to 5.13), while IGF-1 showed a non-significant inducement (SMD = 0.53, 95 % CI -4.40 to 5.45). For dandruff control, two studies demonstrated non-significant improvement in adherent dandruff (OR = 1.31, 95 % CI 0.13-13.65) and a significant increase in free dandruff (OR = 5.39, 95 % CI 1.50-19.43). Hair follicle count, VEGF, IGF-1, and adherent dandruff parameters were recorded with high heterogeneity. For the systematic review, probiotics have shown potential in improving hair growth and controlling dandruff through modulation of the immune pathway and gut-hair axis. The Wnt/β-catenin pathway, IGF-1 pathway, and VEGF are key molecular pathways in regulating hair follicle growth and maintenance.

CONCLUSIONS: This review found significant aspects exemplified by the properties of probiotics related to promoting hair growth and anti-dandruff effect, which serve as a roadmap for further in-depth studies to make it into pilot scales.