What it is
Saw palmetto (Serenoa repens) is a small palm native to the southeastern United States. Its berries contain fatty acids (lauric, oleic, myristic, linoleic) and phytosterols (beta-sitosterol, campesterol, stigmasterol) that inhibit 5-alpha-reductase — the enzyme that converts testosterone to dihydrotestosterone (DHT). DHT is the primary hormonal driver of androgenetic alopecia (male and female pattern hair loss).