To understand hairfall, one must first look beneath the surface. Every hair on your scalp operates on an autonomous genetic clock called the **hair growth cycle**. This cycle consists of three distinct phases: **Anagen** (active growth phase), **Catagen** (transition phase), and **Telogen** (resting and shedding phase).
In androgenetic alopecia (common pattern hair loss), this cycle is disrupted by a hormonal byproduct called **Dihydrotestosterone (DHT)**.
The Mechanism of DHT Miniaturization
DHT is synthesized when the enzyme **5α-reductase** converts testosterone. In individuals with genetic susceptibility, hair follicles in the scalp possess an abundance of androgen receptors.
When DHT binds to these receptors, it triggers a process known as **follicular miniaturization**. The hormone restricts microvascular blood flow to the dermal papilla, starving the follicle of essential oxygen and nutrients. Over successive cycles, the Anagen phase shortens, and the hair grows back thinner, shorter, and less pigmented, until the follicle eventually stops producing hair altogether.
Acts as a natural 5α-reductase inhibitor. By competing with testosterone for the binding sites of the enzyme, it reduces local DHT synthesis in the scalp, preventing miniaturization before it begins.
Operates on a cellular level by inhibiting the enzyme phosphodiesterase. This increases cyclic AMP (cAMP) levels, accelerating cell metabolism and encouraging keratinocyte proliferation to counteract DHT-induced growth suppression.
Clinical Efficacy
In vitro models of human hair follicles exposed to testosterone show severe growth suppression. However, when treated with micro-doses of caffeine, the growth suppression is fully counteracted, and the follicles show a prolonged Anagen phase.
Furthermore, clinical studies on topical saw palmetto have shown a significant increase in hair density and stabilization of hair loss in patients over a 24-week period.