The global hair supplement market is worth over $3.6 billion and growing rapidly. But a 2020 review published in the Journal of the American Academy of Dermatology found that the vast majority of hair supplements on the market have little to no rigorous clinical evidence supporting their claims. Here's what the science actually supports — and what it doesn't.
What Has Good Evidence
Marine protein supplements — derived from fish cartilage and other marine sources — have the strongest evidence base. A double-blind, placebo-controlled trial published in the Journal of Cosmetic Dermatology found that women taking marine protein supplements showed significantly increased hair growth and reduced shedding after 90 days.[1] Viviscal, Nutrafol (contains ashwagandha, saw palmetto, and marine collagen), and Nourkrin are the most clinically studied brands, with multiple published trials supporting their efficacy specifically in women with hair thinning. Omega-3 and omega-6 fatty acid supplements have also shown benefit in randomized controlled trials, as we've covered in our nutrition posts.
The Biotin Problem
Biotin is in virtually every hair supplement, yet a 2017 review in Skin Appendage Disorders found no evidence that biotin supplementation improves hair growth in people who aren't deficient — which is most adults.[2] The doses in most supplements (5,000–10,000 mcg) far exceed the recommended daily intake of 30 mcg. High-dose biotin is also known to interfere with thyroid and troponin lab tests, potentially leading to misdiagnosis. If you're taking high-dose biotin, inform your doctor before any bloodwork.
Saw Palmetto: Promising but Understudied
Saw palmetto inhibits 5-alpha reductase — the enzyme that converts testosterone to DHT — making it a natural alternative to finasteride for DHT-driven hair loss. A 2020 systematic review found modest evidence of benefit in male-pattern hair loss, but studies in women are limited and results are mixed.[3]
What to Do Instead of Buying Everything
Get comprehensive bloodwork: ferritin, vitamin D, zinc, complete blood count, and thyroid panel. Supplement only what you're deficient in. Eat a diverse, nutrient-dense diet. If you want to try a more comprehensive supplement, choose one with published clinical trials (Nutrafol and Viviscal are currently the gold standard). And give any supplement at least 3–6 months before evaluating results — the hair cycle is slow.
Sources:
[1] Ablon G. (2012). A 3-month, randomized, double-blind, placebo-controlled study evaluating the ability of an extra-strength marine protein supplement to promote hair growth. Journal of Cosmetic Dermatology. doi:10.1111/jocd.12040
[2] Patel DP, et al. (2017). A review of the use of biotin for hair loss. Skin Appendage Disorders. doi:10.1159/000462981
[3] Evron E, et al. (2020). Natural hair supplement: Friend or foe? Saw palmetto, a systematic review in alopecia. Skin Appendage Disorders. doi:10.1159/000509905
