Biochemistry of male pattern baldness
Disclaimer: I am not a doctor and nothing I write constitutes medical advice. This article is for informational purposes only, might contain inaccuracies, and should not be used as a substitute for professional medical advice. Read the full disclaimer here: Medical disclaimer
I wrote an intro article on my substack. Read that first. I’m going to organize this page later, but for now, bullet points:
- Is hair loss pathological or adaptive?
- Heat theory (
Larson et al.
- Sweating is more effective on bare skin; that’s why humans don’t have fur
- The skin of the scalp is highly vascular, and shedding hair may be an adaptation that assists heat regulation
- Heat is known to cause mast cell degranulation in a disorder known as heat urticaria
- (my own speculation) Shower water is nearly hot enough (~105F) to trigger some known heat receptors (TRPVs)
- Heat theory ( Larson et al. )
- Could shampoo or conditioner cause hair loss?
- Hard to say. It’s completely possible that there’s some common chemical that causes a subclinical allergic response (-> mast cell degranulation -> PGD2 exocytosis) with repeated exposure.
- Fish oil contains omega-3 fatty acids (specifically eicosapentaenoic acid (EPA) & docosahexaenoic acid (DHA)) that inhibit PGD2 formation in human mast cells in vitro (
Obata et al.
- Two possible reasons
- Dietary EPA is known to modify the phospholipid membrane fatty acid composition ( Lee et al. ). When EPA is used as a substrate for COX-2 instead of arachidonic acid, the resulting compounds (isoprostanes) may not target the same receptors as the prostaglandins.
- EPA/DHA may inhibit COX-2 through some other mechanism
- A study reports that a supplement containing omega-3, omega-6 acids & antioxidants improved hair growth ( Le Floch et al )
- Two possible reasons
- Calcitriol (vitamin D) inhibits expression of COX-2 in mice ( Wang et al. ). This may not be relevant, because the mice were given much, much more vitamin D than one would get from a supplement.
- Tocotrienols (a form of vitamin E) significantly improves hair growth (
Beoy et al.
). Possibly due to antioxidant effects, but the precise mechanism is unclear.
- Looks like tocotrienols and tocopherols are PPAR ligands, which explains their effect.
- COX-2 is upregulated by a variety of inflammatory stimuli (LPS, TNF-alpha…). Could something somewhere else in the body be involved? (needs more investigation)