The Saw Palmetto Serenoa repens is the sole species currently classified in the genus Serenoa. It is a small palm, normally reaching a height of around 2-4 metres. Its trunk is sprawling, and it grows in clumps in sandy coastal lands or as undergrowth in pine woods or hardwood hammocks. It is endemic to the southeastern United States, most commonly along the Atlantic and Gulf coastal plains, but also as far inland as southern Arkansas.

Saw palmetto is a fan palm (Arecaceae tribe Corypheae), with the leaves with a bare petiole terminating in a rounded fan of about 20 leaflets. The leaves are 1-2 m in length, the leaflets 50-100 cm long with prickly sawtooth edges that give the tree its name. They are similar to the leaves of the palmettos of genus Sabal. The flowers are yellowish-white, about 5 mm across, produced in dense compound panicles up to 60 cm long. The fruit is a large reddish-black drupe.

Uses

Native Americans used the fruit for food, but also in the treatment of a variety of urinogenital problems. The European colonists learned of the use of saw palmetto. It was used as a crude extract for at least 200 years for various conditions including asthenia (weakness), recovery from major illness, and urogenital problems. For instance, the Eclectic physician H. W. Felter wrote of it, "Saw palmetto is a nerve sedative, expectorant, and a nutritive tonic, acting kindly upon the digestive tract...Its most direct action appears to be upon the reprodutive organs when undergoing waste of tissue..." (Felter's complete text).

In modern times, much research has been done on extract made from the fruits which are highly enriched with fatty acids and phytosterols . This research has been the subject of a thorough meta-analysis published in the medical journal JAMA and has been shown effective for the treatment of men with symptomatic benign prostatic hyperplasia compared to placebo and the two major categories of drugs used for men with this condition (JAMA meta-analysis). There are also small, positive clinical trials published on the use of saw palmetto extracts topically and internally for male-pattern baldness. There are no studies on whole saw palmetto extracts or crude preparations for any condition despite their widespread use and historical backing.

Other research has shown that it works by multiple mechanisms, including inhibiting 5-alpha-reductase, interfering with dihydrotestosterone binding to the androgen receptor, by relaxing smooth muscle tissue similarly to alpha antagonist drugs, and possibly by acting as a phytoestrogen.

Though men taking saw palmetto may develop mild nausea, reduced libido, or erectile dysfunction, the rate of such problems is clinically and statistically far less common than in men taking drugs to treat BPH symptoms, based on the JAMA meta-analysis cited above. There are no known drug interactions. It should generally be avoided in pregnancy and lactation and in small children due to lack of experience and knowledge in these populations and because of the purely theoretical risk of hormonal interference.

Because the fruit is the part used and because a prolific quantity is produced by an adult saw palmetto tree, this herbal medicine is highly ecologically sustainable. No saw palmetto is currently cultivated for medicine due to the fact that ample quantities are available and always have been from the wild.