The hair loss supplement market generates hundreds of millions of pounds annually on the promise of thicker, fuller hair. Evaluating what the evidence shows — and does not show — for the most popular categories helps patients spend wisely.
Saw palmetto: a plant-derived 5-alpha reductase inhibitor. Some studies show modest reduction in DHT and mild improvement in hair loss scores. Effect size is substantially smaller than finasteride. May be useful for patients who want a milder, non-prescription approach or who cannot take finasteride, but should not be represented as equivalent to pharmaceutical DHT inhibition.
Biotin: well-evidenced for hair loss caused by biotin deficiency. No evidence for benefit in non-deficient individuals, which is most people eating a normal diet. High-dose biotin can interfere with thyroid function tests — worth mentioning to a doctor if you are taking it and having blood tests.
Marine collagen and fish oil: some evidence for improvement in hair and nail quality markers in clinical trials, though study quality is variable. Likely not harmful and modestly beneficial for hair shaft quality, though effects on hair loss specifically are limited.
Ashwagandha: adaptogen with stress-modulating properties. Chronic stress elevates cortisol which can accelerate hair shedding. Ashwagandha’s stress-reducing effects may have an indirect hair benefit via cortisol reduction, though direct evidence for hair loss benefit is limited.
The honest verdict: supplements can plug genuine nutritional gaps and may provide modest adjunct benefit. None replaces finasteride for androgenetic alopecia. The best first step is a blood test to identify actual deficiencies — supplement those specifically rather than buying comprehensive hair supplement stacks that address everything and nothing.
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