From: hubermanlab
Hair growth is a complex biological process influenced by various factors, including hormonal changes. In his podcast, Andrew Huberman explains the pivotal role hormones play in regulating hair growth and loss, focusing on compounds like testosterone, dihydrotestosterone (DHT), and others.
Key Hormonal Players
Testosterone and Dihydrotestosterone (DHT)
Testosterone is well-known for its role in male characteristics, but it also plays a significant role in hair growth. As we age, more testosterone is converted to DHT due to increased activities of the enzyme 5-alpha reductase [01:11:04]. DHT is a more potent androgen that binds to androgen receptors more strongly than testosterone itself.
DHT Impact
Estrogen
While not discussed as deeply as testosterone, estrogen is known to counterbalance the effects of androgens like DHT. Estrogen can optimize hair growth and prolong the anagen phase.
Genetic Influences
The influence of hormones on hair growth is also subject to genetic predispositions. Different individuals inherit various patterns of androgen receptors on their scalps, mostly from their maternal side [01:13:14]. These genetic variations determine specific patterns and degrees of hair loss.
Hormonal Interventions
5-alpha Reductase Inhibitors
A common approach to mitigating hair loss involves using 5-alpha reductase inhibitors, such as finasteride and dutasteride, which prevent the conversion of testosterone to DHT. These inhibitors have shown significant efficacy in both slowing hair loss and stimulating regrowth [01:39:01].
Finasteride
- Reduces DHT levels: By reducing type two 5-alpha reductase, finasteride achieves a marked decrease in systemic DHT levels [01:43:38].
- Effectiveness: Can reduce hair loss in up to 90% of users and increase hair count significantly [01:39:42].
Dutasteride
- More potent than finasteride: Inhibits type one, two, and three 5-alpha reductase enzymes, leading to a drastic reduction in DHT [01:56:05].
- Impact on hair growth: Works faster for hair regrowth but also associated with more pronounced side effects related to DHT suppression [01:56:05].
IGF-1
Insulin-like Growth Factor 1 (IGF-1) is another crucial enhancer of the hair growth phase. IGF-1 serves as an accelerator by extending the anagen phase [01:07:00]. Modification of IGF-1 pathways through controlled hormonal treatments may facilitate longer-lasting hair growth.
Conclusion
The intricate balance of hormones such as testosterone and its derivative, DHT, alongside IGF-1 and others, play vital roles in the lifecycle of hair. By understanding hormonal influences, individuals and professionals can better strategize hair restoration techniques, using both inhibitors of hair loss-promoting hormones and stimulators of hair growth-promoting hormones for effective treatment.