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Saw Palmetto

Botanical Name: Serenoa repens (W. Bartram) Small.
Pharmacopoeial Name: Fructus serenoae repentis.
Synonyms: Sabal serrulata (Michaux) Nuttall ex Schultes.
Common Names: Saw palmetto, sabal.

herb description


Arecaceae (Palmae).

Habitat and Cultivation

Native to coastal regions of southeastern United States, especially Florida; also found in the West Indies and parts of Central America, southern Spain, and North Africa.

Parts Used

Berries. Botanically, the fruit is a drupe with single seed; the oily flesh, not the seed, is used; the fruits are often called “berries.”

Common Forms

Fresh or dried, whole or ground fruit, including powders or tablets.

  • Hydroethanolic Tincture and Fluid Extracts:   70% to 95% alcohol.

  • Lipid/Sterol Extract (LESP):   Hexane or supercritical carbon dioxide (CO2) extraction. LESP may be standardized to “total fatty acid content” between 70% and 95%; however, manufacturers’ preparations may vary. 1

interactions review

Strategic Considerations

Serenoa berries have monographs by the German Commission E 2 and World Health Organization (WHO) 3 and are described in virtually all authoritative literature of Western herbal medicine. In 2002, the United States Pharmacopeia ( USP ) 4 reinstated an official monograph on saw palmetto, which had been deleted from editions after 1916. The primary modern use of saw palmetto extracts is for lower urinary tract symptoms (LUTS) related to benign prostatic hyperplasia (BPH). More than 20 clinical trials have now been conducted to examine the efficacy of saw palmetto for BPH and LUTS. Meta-analyses of 19 of these trials have concluded that the extract is effective for these indications. 5 Saw palmetto berries are typically used in combination with root of Urtica dioica L. and Urtica urens L. (stinging nettles) for mild BPH. 6 Urtica radix is indicated in monographs by the European Scientific Cooperative on Phytotherapy (ESCOP) 7 and WHO 8 for conditions of mild prostatic hyperplasia. A clinical trial using a proprietary blended product (Nutrilite) has established a slight increase in effectiveness for LUTS for the blend versus placebo, although studies comparing the combination product directly with single components are not available. 6

The trial-supported uses of the herb are restricted, in contrast with the original uses of the plant by the indigenous cultures of the southeastern United States, who exploited all parts of the saw palmetto dwarf palm extensively, including as a food for animals and humans, as a fiber source, as well for medical purposes (although the latter are not well documented). 9 Early Western medical uses included as a digestive and respiratory remedy; nutritive to build tissues; reproductive remedy for various male and female conditions, including atrophy of the breasts, dysmenorrhea, irritation, and relaxation of the prostate; aphrodisiac; and sexual vigor and sperm production enhancer. 10,11Modern herbalists have emphasized its anabolic nutritive properties, and general effects that extend beyond the limited view of the herb as a “BPH remedy” for men. 12

There are no direct clinical data on interactions between saw palmetto berries and pharmaceutical drugs, nor are any interactions suggested by the major therapeutic monographs on saw palmetto. Because of the widespread use of the herb in benign prostatic hypertrophy (BPH), as well as an ingredient of herbal formulations for prostate cancer, the potential for interaction with coadministered drugs such as anti-androgens is considerable. These two clinical settings are briefly discussed here.

For mild BPH, a trial course of saw palmetto (in combination with related botanicals) may be used prior to considering drug therapy to examine whether symptoms can be controlled by herbal medication alone. If the lower urinary tract symptoms (LUTS) are refractory to botanical protocols, 5-alpha-reductase (5-AR; 5-α-reductase) inhibition drug therapy (Avodart, Proscar) might be initiated, but combination herb-drug treatments have not been demonstrated to be additive and are unlikely to be beneficial.

In prostate cancer, androgen-deprivation therapy (ADT) is a conventional approach involving one or more endocrine approaches, including luteinizing hormone–releasing hormone (LHRH) agonism (Lupron, Trelstar, Viadur, Zoladex). After causing an initial (several-week) surge in testosterone levels, LHRH agonism subsequently results in castrate levels of testosterone as long as the agent is continued. Alternately, ADT includes LHRH antagonism (Abarelix, Centrilex), antiandrogenics (Androcur, Casodex, Eulexin, Nilandron), and 5-AR inhibition (Avodart, Proscar). Serenoa has been anecdotally incorporated into adjunctive botanical protocols combined with ADT because the herb exhibits antiproliferative effects, such as cyclooxygenase-2 (COX-2) inhibition, as well as inhibition of insulin-like growth factor-1 (IGF-1)–mediated kinase activation that are not dependent on its antiandrogenic effects 13,14(see PC-SPES).

Effects on Drug Metabolism and Bioavailability

Pharmacokinetic interactions between saw palmetto and prescription drugs resulting from herbal modulation of drug-metabolizing systems have not been reported. Two separate controlled trials using healthy volunteers have examined the effects of saw palmetto administration at 320 mg standardized extract daily on cytochrome P450 3A4 (CYP3A4) and CYP2D6 (14 days’ administration) 15 and on CYP1A2, 2D6, 2E1, and 3A4 (28 days’ supplementation). 16 Both studies used probe drug methodology to compare preadministration and postadministration pharmacokinetics of the test substrates, and both failed to find significant differences before and after saw palmetto administration compared with controls, suggesting that the herb poses negligible risk for pharmacokinetic interactions. By contrast, an in vitro study using purified recombinant (i.e., nonhuman) CYP3A4, 2D6, and 2C9 examined the effect of a commercial saw palmetto extract on the kinetics of test substrates of these enzymes. The herb was a potent in vitro inhibitor of all three CYPs tested. 17 These researchers did not analyze the content of the saw palmetto product used in the study, and accurate molecular concentration and composition of the material were not established. Conflict between in vitro and in vivo data in this area is not uncommon, but until/unless further data to the contrary become available, saw palmetto is unlikely to exhibit marked pharmacokinetic interactions with pharmaceutical substrates of the principal CYP enzymes.

theoretical, speculative, and preliminary interactions research, including overstated interactions claims
Steroidal Sex Hormones
Anticoagulants, Oral Vitamin K Antagonists
  • 1.Habib FK, Wyllie MG. Not all brands are created equal: a comparison of selected components of different brands of Serenoa repens extract. Prostate Cancer Prostatic Dis 2004;7:195-200.View Abstract
  • 2.Blumenthal M, Busse W, Goldberg A et al. The Complete German Commission E Monographs. Austin, Texas: American Botanical Council: Integrative Medicine Communications; 1998:201.
  • 3.WHO. Fructus Seronoae Repentis. WHO Monographs on Selected Medicinal Plants. 2 vol. Geneva: World Health Organization; 2002:285-289.
  • 4.United States Pharmacopeia. USP online. Dietary supplements. Botanical Monographs. Saw Palmetto. Accessed July 2003 vol; 2000.
  • 5.Boyle P, Robertson C, Lowe F, Roehrborn C. Updated meta-analysis of clinical trials of Serenoa repens extract in the treatment of symptomatic benign prostatic hyperplasia. BJU Int 2004;93:751-756.View Abstract
  • 6.Vahlensieck W Jr. [With alpha blockers, finasteride and nettle root against benign prostatic hyperplasia: which patients are helped by conservative therapy?]. MMW Fortschr Med 2002;144:33-36.View Abstract
  • 7.ESCOP. Urticae Radix. ESCOP Monographs on the Medicinal Uses of Plant Drugs. Fascicule 2 vol. Exeter, UK: European Scientific Cooperative on Phytotherapy; 1996.
  • 8.WHO. Radix Urticae. WHO Monographs on Selected Medicinal Plants. 2 vol. Geneva: World Health Organization; 2002:329-341.
  • 9.Brinker F. Saw palmetto: Florida fruit for flow and fecundity. Complex Herbs—Complete Medicines: a Merger of Eclectic and Naturopathic Visions of Botanical Medicine. Sandy, Ore: Eclectic Medical Publications; 2004.
  • 10.Ellingwood F, Lloyd J. Seronoa serrulata. The American Materia Medica: Therapeutics and Pharmacognosy. Eclectic Medical Publications, Portland, Ore; 1983 ed. Cincinnati; 1919.
  • 11.Felter H. Serenoa. The Eclectic Materia Medica: Pharmacology and Therapeutics. Eclectic Medical Publications, Portland, Ore; 1985 ed. Cincinnati; 1922:628.
  • 12.Winston D. Saw Palmetto for Men and Women. Pownal, Vt: Storey Books; 1999.
  • 13.Goldmann WH, Sharma AL, Currier SJ et al. Saw palmetto berry extract inhibits cell growth and COX-2 expression in prostatic cancer cells. Cell Biol Int 2001;25:1117-1124.View Abstract
  • 14.Wadsworth TL, Carroll JM, Mallinson RA et al. Saw palmetto extract suppresses insulin-like growth factor-I signaling and induces stress-activated protein kinase/c-Jun N-terminal kinase phosphorylation in human prostate epithelial cells. Endocrinology 2004;145:3205-3214.View Abstract
  • 15.Markowitz JS, Donovan JL, Devane CL et al. Multiple doses of saw palmetto (Serenoa repens) did not alter cytochrome P450 2D6 and 3A4 activity in normal volunteers. Clin Pharmacol Ther 2003;74:536-542.View Abstract
  • 16.Gurley BJ, Gardner SF, Hubbard MA et al. In vivo assessment of botanical supplementation on human cytochrome P450 phenotypes: Citrus aurantium, Echinacea purpurea, milk thistle, and saw palmetto. Clin Pharmacol Ther 2004;76:428-440.View Abstract
  • 17.Yale SH, Glurich I. Analysis of the inhibitory potential of Ginkgo biloba, Echinacea purpurea, and Serenoa repens on the metabolic activity of cytochrome P450 3A4, 2D6, and 2C9. J Altern Complement Med 2005;11:433-439.View Abstract
  • 18.Goepel M, Dinh L, Mitchell A et al. Do saw palmetto extracts block humanα1-adrenoceptor subtypes in vivo? Prostate 2001;46:226-232.
  • 19.Glemain P, Coulange C, Grapin F, Muszynski R. What is the benefit of combining tamsulosin with Serenoa repens versus tamsulosin alone on storage/filling and voiding lower urinary tract symptoms (LUTS)? Eur Urol Suppl 2002;1:108.
  • 20.Harkness R, Bratman S. Handbook of Drug-Herb and Drug-Supplement Interactions. St Louis: Mosby; 2003.
  • 21.Cheema P, El-Mefty O, Jazieh AR. Intraoperative haemorrhage associated with the use of extract of saw palmetto herb: a case report and review of literature. J Intern Med 2001;250:167-169.View Abstract
  • 22.Stepanov VN, Siniakova LA, Sarrazin B, Raynaud JP. Efficacy and tolerability of the lipidosterolic extract of Serenoa repens (Permixon) in benign prostatic hyperplasia: a double-blind comparison of two dosage regimens. Adv Ther 1999;16:231-241.View Abstract
  • 23.Small EJ, Frohlich MW, Bok R et al. Prospective trial of the herbal supplement PC-SPES in patients with progressive prostate cancer. J Clin Oncol 2000;18:3595-3603.View Abstract
  • 24.Porterfield H. UsToo PC-SPES surveys: review of studies and update of previous survey results. Mol Urol 2000;4:289-291; discussion 293.View Abstract
  • 25.Pfeifer BL, Pirani JF, Hamann SR, Klippel KF. PC-SPES, a dietary supplement for the treatment of hormone-refractory prostate cancer. BJU Int 2000;85:481-485.View Abstract
  • 26.De la Taille A, Buttyan R, Hayek O et al. Herbal therapy PC-SPES: in vitro effects and evaluation of its efficacy in 69 patients with prostate cancer. J Urol 2000;164:1229-1234.View Abstract
  • 27.Ko R, Wilson RD, Loscutoff S. PC-SPES. Urology 2003;61:1292.View Abstract
  • 28.Bonham M, Arnold H, Montgomery B, Nelson PS. Molecular effects of the herbal compound PC-SPES: identification of activity pathways in prostate carcinoma. Cancer Res 2002;62:3920-3924.View Abstract