The Science of Healthy Hair, Hair Loss, and Regrowth | Huberman Lab 

Dr. Andrew Huberman, Ph.D. is a Professor of Neurobiology and Ophthalmology at Stanford University School of Medicine. His lab focuses on neural regeneration, neuroplasticity, and brain states such as stress, focus, fear, and optimal performance.

In this episode of the Huberman Lab Podcast, Andrew Huberman explains the biology of hair, hair growth, why hair growth slows, and what causes it to fall out. He then breaks down chemical and mechanical approaches to slow down hair loss, potential side effects, expectations of results, and much more!

Host: Andrew Huberman (@hubermanlab)

Stem cells give rise to hairs we have on our heads and the surface of our body – every hair we have is there because of a stem cell population that gives rise to that hair

Parts of hair: hair root is the portion below the skin; the shaft is the part that grows out above the skin At the base there’s a pocket (hair cave) below the root with a population of stem cells; melanin also lives here and gives hair color Next to every hair root below the skin is a sebaceous gland – sebum is the oil produced by these glands Sebum is a strong antibacterial and hydrates the hair The erector pili muscle lies below bulb and goes to surface of skin – this is what gives rise to goosebumps and makes hairs stand Capillaries go into the bulb region to support stem cells and melanocytes, delivering oxygen and nutrients

Hairs are made up of a bunch of little proteins called keratin People experience tremendous anxiety and even depression about hair loss Psychological well-being can impact the coloration and growth rate of hair

By age 50, about 50% of men and women will experience some sort of hair loss Hair loss is ongoing from age 30 but by age 50 it becomes more noticeable

There are mechanical (such as scalp massaging) and chemical (such as hormone shampoos) approaches to slowing and reversing hair loss

Three phases of hair growth lifecycle: Anagen phase: stem cells in the bulb give rise to proteins that make up hair; hair grows deep within the root and up through the skin The growth phase varies depending on location – hairs on the head can grow for about 8 years if uncut; hairs on eyebrows grow about 4.2mm per month but will fall out every few months Catagen phase: hair recedes from the bulb up toward the surface (in other words, recedes from inside out) Telogen phase: no new hair or proteins are added by stem cells; stem cell pinches off and recedes and dies, taking stem cells and melanocytes with it Hair on the scalp can reenter the growth anagen phase in proper conditions

Dihydrotestosterone (DHT) causes changes in the bulb region where stem cells reside; it shortens or halts the anagen phase of hair growth and extends or promotes the catagen and telogen phase There are real biochemical reasons testosterone makes your hair fall out

Minoxidil (AKA Rogaine) was initially developed to treat hypertension by causing vasodilation; it was also found to slow the loss of hair by extending the anagen phase via increasing blood flow to hair cells Side effects and importance of dosing: can lower blood pressure too much depending on the sensitivity, can increase prolactin, can affect dopamine release (antagonistic to prolactin), may induce gynecomastia, can lower libido Can be used prescription and nonprescription and topical (on the scalp for 3-5 minutes) or oral; dose varies widely from .25mg to 5mg Start with a low dose and increase as needed depending on need and side effects Minoxidil is a long-term solution, maybe even the rest of life

Mechanical accelerators: heating, lighting, or massaging of the scalp is designed to increase blood flow to the scalp Expanding blood vessels and capillaries in this way won’t completely halt or reverse hair loss but it will put you in a better position to keep the hair you have a strong genetic predisposition

Tadalafil (AKA Cialis; low dose, 2.5-5mg) was initially discovered to treat prostrate and found to increase blood flow to scalp & stem cell niche Won’t reverse hair loss but will slow the rate of hair loss like minoxidil

Platelet rich plasma (PRP) injection is being used in multiple regions of the body, including scalp – it’s not stem cells; PRP is legal in U.S. and other places – it takes platelets and injects back into the body to encourage nutrient delivery Moderately successful but no sufficient clinical data to suggest a strong recommendation

Microneedling over the scalp has been shown to reactivate hairs in the telogen phase and stimulate more hair growth, as well as a good augment to hormone-based treatments (like minoxidil) Low-level inflammation can cause changes in cells to reactive again Microneedling seems to have some positive benefits but the studies aren’t great

Botox is a bacterial toxin that cuts the protein that leads to synaptic release – when used for hair growth, it is applied to the scalp to relieve tension in the scalp to decrease tensile nature of scalp skin The efficacy of Botox in the scalp is not well studied and does need to be performed by someone skilled to ensure the correct dose

Insulin growth factor-1 (IGF1) is a strong accelerator of hair growth by extending the androgen phase for a longer period of time

Cyclic AMP is also a stimulator of hair growth follicles, acting as a messenger between the surface of cells and transmitting deep within the cells – this also extends the androgen phase

Things that shorten the androgen phase, extend the catagen phase or telogen phase Two breaks on growth: phosphodiesterase (PDE) and TGF-beta-2

Androgen-related alopecia (pattern hair loss)is testosterone and testosterone-derivative-related hair loss which takes place in men and women A healthy woman has higher levels of testosterone than estrogen, but less testosterone than men

Androgens inhibit IGF-1 and cyclic AMP – DHT itself is not bad but does inhibit hair growth

The pattern of androgen receptors you inherit does come from your mother’s genes , though it’s not as simple as looking at your mother’s father to determine whether you’ll be bald

Androgen receptors on the face are also responsible for hair growth on; similarly, wherever you grow hair, you can assume you have a high density of androgen receptors there

Caffeine is a potent PDE inhibitor that indirectly stimulates IGF-1 (remember, IGF-1 is a strong accelerator of hair growth) and reduces apoptosis of cell niche You can’t just drink more caffeine but topical caffeine application 3x per week can be as potent as minoxidil without the side effects

Both minoxidil and caffeine are preventative for hair loss over time, and not to create new hair growth

Increasing IGF-1 will directly stimulate hair growth – sleep at a habitual window to get natural growth hormone release at night; you can also use prescription IGF-1 or growth hormone Remember, growth hormone increases the growth of everything so there is an increased cancer risk

Increase insulin sensitivity because being insulin resistant and obese can lead to hair loss Myo-inositol, berberine, and metformin (prescription) can all help but try exercise and a healthy diet first

Iron and ferritin play a key role in the cell growth pathway that goes from stem cells to stimulation of keratin within the hair cell DHT shortens the hair growth phase and miniaturizes the hair follicle

Saw palmetto extract (dose 50-100mg per serving up to 300mg per day) will help hold on to some hair and maybe grow new hair but it’s not a robust treatment in and of itself Reduces 5-alpha reductase, therefore reducing DHT

Curcumin is known in some people to be a potent inhibitor of 5-alpha reductase and DHT

Ketoconazole shampoo (Keeps and other vendors below) can disrupt some of the fungal growth on the scalp and reinforces the property of sebum oil, with about an 80% response rate when used 3-4x per week Concentration has to be at least 2% or higher concentration; side effects can affect about 8% of people and can lead to dry and bitter hair

Finasteride reduces DHT and can increase hair growth by about 20% and can reduce hair loss in 90% of users Side effects are significant if not dosed properly; there is an oral form and topical form (harder to dose but fewer side effects) – start with the lowest effective dose and be patient, it could take a few months to kick in Tablet dosing: 0.5-1.0mg per day seems to be the effective and safe starting point for most Topical dosing: 1mL (minimum 2%) used once per week Post-finasteride symptom has been increasingly reported – males taking finasteride who stop taking it experience very significant symptoms like reduced mood, libido, erectile function, etc. This occurs more in males in their 20s and 30s than in older males

Dutasteride taken orally, about 0.5-2.5mg taken orally works 2-5x faster than finasteride and reduces DHT by 95% Associated with a lot of side effects – reduced sex drive, gynecomastia, etc. This is a drastic route, don’t start here – be patient with other treatments first

Articles Microneedling and Its Use in Hair Loss Disorders: A Systematic Review ( Dermatology and Therapy ) Caffeine and Its Pharmacological Benefits in the Management of Androgenetic Alopecia: A Review ( Skin Pharmacology and Physiology ) The effectiveness of combination therapies for androgenetic alopecia: A systematic review and meta-analysis ( Dermatologic Therapy ) Differential effects of caffeine on hair shaft elongation, matrix and outer root sheath keratinocyte proliferation, and transforming growth factor‐β2/insulin‐like growth factor‐1‐mediated regulation of the hair cycle in male and female human hair follicles in vitro ( British Journal of Dermatology ) The structure of people’s hair ( PeerJ )

Other Resources Keeps Nurx Siena Health Intelligent Maple Holisitics Ouai R+Co Microneedling stamps and rollers