Saw palmetto extract from the berries of Serenoa repens contains fatty acids and phytosterols with mild anti-androgenic effects.
Mechanism — Weak 5-alpha-reductase inhibition (much weaker than finasteride), anti-inflammatory action in prostate tissue, and possible androgen receptor binding. Effect size is modest but real for BPH symptoms.
Use case — Mild BPH, lifestyle-level support for hair preservation. Typical 160 mg 2x/day of liposterolic extract (85-95% fatty acids).
Caveats — Not a substitute for finasteride if pharmacologic effect is needed. Effects take 4-6 months to assess. Generally well-tolerated; mild GI side effects in some.