Serenoa repens, the only species in its genus, is native to the southeastern United States, especially Florida. It is a short palm with fanlike leaves and sharp-toothed petioles. The fruit is a drupe with a thin layer of oily pulp. The fruit was sometimes used as a food, but it has a somewhat odd taste and the pulp is so meager that its use as food cannot be very efficient. It is traditionally used as a tonic and to treat urinary problems, especially prostate trouble. Lipophilic (nonpolar) extracts of S. repens are now commonly used to relieve age-associated urinary symptoms that are widely termed Lower Urinary Tract Symptoms (LUTS); in North America, these symptoms in men are termed Benign Prostatic Hyperplasia (BPH). Saw palmetto products are also sometimes claimed to have hormonal effects such as reduction of hair loss, prevention of impotence, or breast enlargement.

Saw palmetto?s traditional use to treat BPH-related urinary symptoms is fairly well demonstrated, with positive results from numerous studies totalling thousands of patients. Studies that have compared saw palmetto directly to the pharmaceutical drug finasteride have found that the herb offered similar symptomatic relief with fewer side effects (and lower cost). Like several other herbs used for BPH, including pygeum, nettle root, and pumpkin seed, saw palmetto contains beta-sitosterol, a known active ingredient with demonstrated bioactivity, and other phytosterols. Mechanisms of activity are not completely understood, but include the inhibition of an enzyme called 5alpha-reductase. There is no significant evidence that saw palmetto has any activity against prostate cancer. However, it has been shown that while pharmaceutical drugs inhibiting 5alpha-reductase reduce the secretion of prostate specific antigen (PSA), saw palmetto does not; this means that saw palmetto, unlike the pharmaceuticals, would not interfere with use of PSA tests to screen for or monitor prostate cancer. Unfortunately, saw palmetto products vary significantly in quality, and a few have been found to be much less potent than claimed; the buyer must therefore beware.

Selected References

Debruyne, F., P. Boyle, F. Calais Da Silva, J. G. Gillenwater, F. C. Hamdy, P. Perrin, P. Teillac, R. Vela-Navarrete, J. P. Raynaud, and C. C. Schulman. 2004. Evaluation of the clinical benefit of Permixon and tamsulosin in severe BPH patients ? PERMAL study subset analysis. Eur. Urol. 45:773-779.

Feifer, A. H., N. E. Fleshner, and L. Klotz. 2002. Analytical accuracy and reliability of commonly used nutritional supplements in prostate disease. J. Urol. 168:150-154.

Habib, F. K., M. Ross, C. K. Ho, V. Lyons, and K. Chapman. 2005. Serenoa repens (Permixon) inhibits the 5alpha-reductase activity of human prostate cancer cell lines without interfering with PSA expression. Intl. J. Cancer 114:190-194.

Hawkes, A. D. 1950. Notes on the palms. 2. Saw Palmetto Serenoa repens Small. Natl. Hort. Mag. 29:93-95.

Nelson, G. 1996. The Shrubs and Woody Vines of Florida. Pineapple Press, Inc.: Sarasota, FL.

Prager, N., K. Bickett, N. French, and G. Marcovici. 2002. A randomized, double-blind, placebo-controlled trial to determine the effectiveness of botanically derived inhibitors of 5-alpha-reductase in the treatment of androgenetic alopecia. J. Altern. Complement. Med. 8:143-152.

Wilt, T., A. Ishani, and R. MacDonald. 2002. Serenoa repens for benign prostatic hyperplasia. Cochrane Database Syst. Rev. 2002;(3):CD001423.

Zona, S. 1997. The genera of Palmae (Arecaceae) in the southeastern United States. Harvard Pap. Bot. 11: 71-107.

Zona, S. A. 2000. Arecaceae. Pp. 95-123 in: Flora of North America Editorial Committee, eds. Flora of North America, vol. 22. Oxford University Press: New York.