Family

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

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.

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