Enhancing hair growth through phytochemicals: mechanisms, supporting evidence, and future directions.

Aims: To explore the mechanisms, formulations, delivery strategies, and therapeutic potential of phytochemicals in promoting hair growth, emphasizing their effects on hair follicle physiology and growth cycles.

Methods: Databases including PubMed, Springer, Wiley Online Library, Web of Science, CBM, CNKI, Elsevier, Google Scholar, and other databases were searched using key terms such as "phytochemicals," "hair growth," "hair follicles," "growth factors," and "natural treatments" were used to identify experimental and clinical studies on phytochemicals affecting hair growth.

Key findings: Key phytochemicals stimulate hair follicles and promote keratinocyte proliferation. Malva verticillata influences the (Wingless/Integrated and β-catenin) Wnt/β-catenin pathway and AKT (protein kinase B) signaling. Elephantopus scaber L. extracts elevate insulin-like growth factor 1 (IGF-1) and vascular endothelial growth factor (VEGF), while Sophora flavescens boosts IGF-1 and keratinocyte growth factor (KGF) by increasing mRNA levels. Similarly, Epigallocatechin-3-gallate activates AKT signaling, caffeine reduces transforming growth factor-β2 (TGF-β2) and raises IGF-1, and Carthamus tinctorius enhances VEGF and KGF while suppressing TGF-β1. Although evidence highlights their potential, challenges remain in improving bioavailability and standardizing formulations.

Conclusions: Phytochemicals offer natural, safer alternatives for promoting hair growth with fewer side effects than conventional drugs. Further research is needed to optimize formulations and improve bioavailability.