Saw palmetto (Serenoa repens (W.Bartram) Small or Sabal serrulata (Michx.) Schult.f.) is a small species of palm, native of southern part of USA.

Main constituent of Serenoa and of respective extracts from fruits are free fatty acids, methyl and ethyl esters of fatty acids, sterols, fatty alcohols, carotenoids, essential oils and polysaccharides. Free fatty acids and their ethyl-esters are thought to be responsible for the bio-activity of this plant through an inhibition of 5-alpha reductase, the enzyme which, in the cells of the prostate, is deputed to the catalysis of conversion of testosterone to dihydrotestosterone (DHT); an excess of DHT is thought to be one of the aetiologic agents of benign prostatic hypertrophy (BPH), a common disturbancy in male adult population. Polysaccharides are thought to exert an antiphlogistic function.

Treatment with standardized extracts of saw palmetto is useful to treat symptoms of prostatic hypertrophy and to stabilize urodynamic of subjects (reduction of symptoms like frequent urination).

Extracts of Serenoa are characterized by high levels of safety and tolerability.