April 10, 2023 • 2hr 0min
The Science of Healthy Hair, Hair Loss and How to Regrow Hair
Huberman Lab
Key Takeaways
- Hair growth occurs in three phases: anagen (growth), catagen (regression), and telogen (rest). The duration of these phases determines hair length and growth patterns.
- Blood flow and oxygen delivery to hair follicle stem cells is critical for maintaining hair growth. This is why treatments like minoxidil that increase blood flow can help with hair loss.
- Dihydrotestosterone (DHT) is the main hormone responsible for male and female pattern hair loss. It shortens the anagen phase and miniaturizes hair follicles.
- Finasteride and dutasteride work by inhibiting the enzyme that converts testosterone to DHT, thereby reducing DHT levels and slowing hair loss.
- Combination treatments using both mechanical stimulation (like microneedling) and chemical treatments (like finasteride) tend to be most effective for regrowing hair.
- Low doses of treatments started early and maintained long-term tend to be most effective with fewest side effects for hair loss prevention and regrowth.
- Individual response to hair loss treatments varies widely. Working with a doctor to find the right combination and dosage is important.
Introduction
In this episode, Dr. Andrew Huberman discusses the biology of hair growth and loss, as well as various treatments for maintaining hair and stimulating new growth. He explains the anatomy of hair follicles, the phases of hair growth, and the key hormones and growth factors involved. Huberman then reviews both mechanical and chemical approaches to treating hair loss, including medications, supplements, and procedures like microneedling. He emphasizes the importance of understanding the mechanisms behind different treatments in order to evaluate their potential effectiveness and side effects.
Topics Discussed
Hair Anatomy and Growth Cycle (13:19)
Huberman explains the basic anatomy of a hair follicle, including:
- The hair shaft that extends above the skin
- The hair root below the skin surface
- The hair bulb at the base containing stem cells and pigment-producing melanocytes
- The sebaceous gland that produces sebum to lubricate and protect the hair
- The arrector pili muscle that causes hair to stand up
He then describes the three phases of hair growth:
- Anagen phase: Active growth phase lasting 2-8 years for scalp hair
- Catagen phase: Regression phase where hair stops growing
- Telogen phase: Resting phase before hair falls out
The duration of these phases determines hair length and growth patterns in different body areas.
Factors Affecting Hair Growth (26:05)
Key factors that regulate the hair growth cycle include:
- Blood flow and oxygen delivery: Critical for supporting hair follicle stem cells
- IGF-1 (insulin-like growth factor 1): Promotes anagen phase and hair growth
- Androgens like DHT: Shorten anagen phase and miniaturize follicles
- Cyclic AMP: Messenger that promotes hair growth
- PDE (phosphodiesterase): Enzyme that inhibits hair growth
Minoxidil and Blood Flow (36:55)
Huberman discusses minoxidil, one of the most common hair loss treatments:
- Originally developed as a blood pressure medication
- Works by increasing blood flow to hair follicles
- Can be taken orally or applied topically
- Typical dosages range from 0.25-5mg orally or 5% solution topically
- Side effects can include dizziness, swelling, and increased prolactin
He notes that minoxidil is most effective for maintaining existing hair rather than regrowing new hair.
Other Treatments to Increase Blood Flow (45:37)
Additional approaches to improve blood flow to hair follicles include:
- Low-dose tadalafil: 2.5-5mg daily can increase overall blood flow
- Scalp massage: May temporarily increase blood flow but effects are limited
- PRP (platelet-rich plasma): Injections of growth factors from blood
- Microneedling: Creates micro-injuries to stimulate blood flow and healing
Microneedling for Hair Growth (56:10)
Huberman explains how microneedling can stimulate hair growth:
- Uses tiny needles (0.5-2.5mm long) to create micro-injuries in scalp
- Stimulates stem cells and increases blood flow
- Most effective when combined with other treatments like minoxidil
- Can help regrow hair even in "dead zones" with no visible hair
- Typically done weekly or biweekly for several months
Androgens and Pattern Hair Loss (1:06:27)
Huberman discusses the role of androgens in hair loss:
- DHT (dihydrotestosterone) is the main androgen responsible for pattern hair loss
- Converted from testosterone by the enzyme 5-alpha reductase
- Shortens anagen phase and miniaturizes hair follicles
- Affects both men and women, though patterns differ
- Genetic factors determine sensitivity of follicles to DHT
Topical Caffeine for Hair Loss (1:15:46)
Caffeine is emerging as a potential hair loss treatment:
- Acts as a phosphodiesterase inhibitor to promote hair growth
- Applied topically in shampoos or solutions
- May be as effective as minoxidil with fewer side effects
- Typically used 2-3 times per week
- Drinking caffeine is not effective - must be applied topically
Growth Hormone and Hair (1:21:06)
Huberman explains how growth hormone and IGF-1 affect hair:
- Growth hormone stimulates IGF-1 production
- IGF-1 promotes anagen phase and hair growth
- Can be increased through prescription medications or peptides
- Carries potential side effects and cancer risks
- Maintaining insulin sensitivity is important for IGF-1 function
Saw Palmetto and Natural DHT Blockers (1:27:04)
Some natural supplements may help block DHT:
- Saw palmetto: Weak 5-alpha reductase inhibitor
- Typical dose is 300mg daily divided into 2-3 doses
- Has few side effects but modest efficacy
- Curcumin: May inhibit 5-alpha reductase but can have side effects
Ketoconazole for Hair Loss (1:33:22)
Ketoconazole shampoo can help with hair loss:
- Originally an antifungal treatment
- Has mild anti-androgen effects in hair follicles
- Use 2% concentration shampoo 2-4 times weekly
- Leave on scalp for 3-5 minutes before rinsing
- Can cause some dryness/brittleness of hair
Finasteride for Hair Loss (1:38:46)
Huberman discusses finasteride, one of the most effective hair loss medications:
- Inhibits 5-alpha reductase to reduce DHT levels
- Can increase hair count by 20% and slow loss in 90% of users
- Available in oral and topical forms
- Typical oral dose is 0.5-1mg daily
- Side effects can include sexual dysfunction and mood changes
- Start with lowest effective dose and increase slowly if needed
Post-Finasteride Syndrome (1:51:00)
Huberman explains the controversial "post-finasteride syndrome":
- Reported symptoms like sexual dysfunction and depression after stopping finasteride
- More common in younger men using for hair loss vs older men for prostate issues
- May relate to DHT's role in brain development into 20s and 30s
- Exact mechanism still unclear but raises caution about use in young men
Dutasteride for Hair Loss (1:56:01)
Dutasteride is an even stronger 5-alpha reductase inhibitor:
- Inhibits all three types of 5-alpha reductase enzyme
- Reduces DHT levels by up to 95%
- Works 2-5 times faster than finasteride
- Higher risk of side effects like sexual dysfunction
- Typical dose is 0.5-2.5mg daily
Combination Approaches (1:58:53)
Huberman emphasizes that combination treatments tend to be most effective:
- Combining mechanical (e.g. microneedling) and chemical treatments
- Microneedling + finasteride is particularly effective
- Can also add ketoconazole shampoo, saw palmetto, etc.
- Be cautious about combining too many DHT-lowering treatments
- Work with a doctor to find the right combination and dosage
Conclusion
Huberman concludes by emphasizing the importance of understanding the mechanisms behind different hair loss treatments in order to evaluate their potential effectiveness and side effects. He recommends starting with the lowest effective doses of treatments and combining mechanical and chemical approaches for best results. Given the wide variation in individual response, working closely with a doctor to find the right treatment plan is crucial. With the right approach, many people can successfully slow hair loss and even regrow some hair, but patience and consistency are key.
