Efficacy of polyphenolic compounds for hair regeneration: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND: Non-scarring alopecia, including androgenetic alopecia, alopecia areata, and telogen effluvium, is highly prevalent and often associated with significant psychosocial burden. Although treatments such as minoxidil and finasteride are available, variability in response and tolerability concerns have increased interest in alternative therapeutic approaches. Polyphenolic compounds have attracted attention due to their antioxidant, anti-inflammatory, and immunomodulatory properties. OBJECTIVES: This systematic review and meta-analysis evaluated the efficacy of oral and topical polyphenolic interventions for hair regeneration in adults with non-scarring alopecia. METHODS: A systematic search of PubMed/MEDLINE, Scopus, Web of Science, and Cochrane CENTRAL was conducted according to PRISMA 2020 guidelines (PROSPERO: CRD420251230149). Randomized, blinded controlled trials were included. Primary outcomes were objective trichoscopic measures, including hair density and total area hair count. RESULTS: Thirty-two randomized controlled trials involving 2,183 participants were analyzed. Compared with controls, polyphenolic interventions significantly improved hair density (SMD 0.90; 95% CI 0.51-1.30) and total area hair count (SMD 1.03; 95% CI 0.42-1.63), although substantial heterogeneity was observed. Direct comparisons with minoxidil did not show significant differences in overall hair count outcomes. CONCLUSIONS: Current evidence suggests that selected polyphenolic formulations may represent a potential adjunctive therapeutic approach in non-scarring alopecia, though further standardized and long-term trials are warranted.