Scientific Name(s): Brahea serrulata, Chamaerops serrulata Michx, Corypha repens, Sabal serrulata, Sabal serrulatum, Serenoa repens ( W. Bartram) Small, Serenoa serrulata (Michx) G. Nicholson
Common Name(s): American dwarf palm tree, Cabbage palm, Dwarf palmetto, Fan palm, Fructus Serenoae Repentis, Sabal fructus, Sabal palm, Saw palmetto, Saw palmetto berry, Scrub palm, Scrub palmetto, Serenoa
Saw palmetto has been used to treat symptoms of benign prostatic hyperplasia (BPH), but evidence from quality clinical trials and a meta-analysis does not support this use. Data suggesting a positive effect on erectile dysfunction are limited, and results from studies evaluating the effect of saw palmetto on outcomes of transurethral resection of the prostate surgery are equivocal.
Benign prostatic hyperplasia: 320 mg/day standardized extract.
Contraindications have not been identified. Use in children younger than 12 years is not recommended.
Information regarding safety and efficacy in pregnancy and lactation is lacking. Because saw palmetto affects androgen and estrogen metabolism, and there is no rationale for use in this population, saw palmetto should be avoided.
See Drug Interactions section.
Results from clinical trials note that saw palmetto products are generally well tolerated, with occasional reports of adverse GI effects and headache.
Information is limited.
- Arecaceae (palm)
Saw palmetto is a low, scrubby palm that grows in the coastal plain of Florida and other southeastern states. Its fan-shaped leaves have sharp saw-toothed edges that give the plant its name. Dense clumps of saw palmetto can form an impenetrable thicket. The plant has a characteristic creeping rhizome, one end of which appears above ground. The sweet-smelling fruit is dark brown to black, with a smooth drupe and a single flattened, reddish brown seed. The abundant 2 cm long berries are harvested in the fall and dried for medicinal use. They also serve as a source of nutrition for deer, bears, and wild pigs.1, 2
Native tribes of Florida relied on saw palmetto berries for food; however, Europeans often found the taste of the berries objectionable. While native medicinal use is not recorded, saw palmetto was introduced into Western medical practice in the 1870s and was favored by eclectic medical practitioners for prostate and other urologic conditions. Saw palmetto berries were officially included in the US Pharmacopeia (USP) in 1906 and 1916 and in the National Formulary from 1926 to 1950. While use in the United States declined after that time, saw palmetto has long been a staple phytomedicine in Europe. However, interest in the plant has been rekindled, and saw palmetto is ranked among the top 10 herbal products in the United States, primarily for its use in BPH. Folkloric uses include for baldness, to increase appetite, to build and strengthen tissue, to increase metabolism, for thyroid disorders, for asthma and chest congestion, and for polycystic ovary syndrome.3, 4, 5, 6
Saw palmetto berries primarily contain free fatty acids (70% to 95%) and their ethyl esters, 0.2% to 0.5% phytosterols (beta-sitosterol, stigmasterol, and daucosterol), long-chain alcohols (0.15% to 0.35%), and lipids. The fatty acids include oleic, lauric, myristic, palmitic, linoleic, caproic, caprylic, capric, palmitoleic, steric, and linolenic acids. In addition, flavonoids, polysaccharides, and other minor constituents have been identified. Standards and analytical methods have been described for the extract and its constituents.2, 7, 8, 61 A specific ratio of naturally occurring caproic, caprylic, capric, myristic, palmitic, stearic, oleic, linoleic, and linolenic acids to lauric acid are required by USP for authentication. Although little published evidence is available regarding adulteration of products, unpublished analyses by reputable suppliers indicate some adulteration is present in the supply chain. Known adulterants include fruit from a closely related palm species (eg, Acoelorrhaphe wrightii), use of unripe berries, and the addition of vegetable oils to extracts and/or full substitution of saw palmetto extract with other vegetable oils (ie, canola, coconut, olive, palm, peanut, and sunflower oils). The adulteration rate seems to be low (1 of 22 and 0 of 57 products tested in 2 separate analyses) and may also somewhat depend on the weather conditions in the current or immediate prior season.61
Uses and Pharmacology
Benign prostatic hyperplasia
Saw palmetto's mechanism of action in suppressing the symptoms of BPH is poorly understood. Animal and human in vitro studies have led to several different hypotheses, including antiandrogenic and anti-inflammatory activities. Antiproliferative and proapoptotic actions via inhibition of growth factors and inhibition of adipocyte differentiation have also been described.2, 5, 9, 10, 11, 12
An updated Cochrane systematic review and meta-analysis has been published, including data from recent large, high-quality trials. Saw palmetto was no more effective than placebo in decreasing lower urinary tract symptoms associated with BPH in a meta-analysis13, 59 of 3 quality trials, including the Complementary and Alternative Medicine for Urological Symptoms (CAMUS) and Saw palmetto Treatment for Enlarged Prostates (STEP) studies (N = 661).14, 15, 16 The weighted mean difference using validated American Urological Association Symptom Index/International Prostate Symptom Score indices was −0.16 points (95% CI, −1.45 to 1.14) for lower urinary tract symptoms. For increased maximum urinary flow rate, the weighted mean difference was also not significant compared with placebo (0.40 mL/s [95% CI, −0.30 to 1.09]).13 Furthermore, a dose escalation study found no benefit even with triple the usual dosage.14 These findings have similarly been reported by other reviewers, and currently the only place for saw palmetto in the therapy of BPH symptoms is among patients who wish to receive phytotherapy in conjunction with standard medical treatments.17, 18, 19 Results from open-label trials, retrospective analyses, and trials evaluating treatment with combinations of various natural products were not included due to methodological limitations.20, 21, 22 A sponsor-funded phase 2 placebo-controlled, randomized clinical trial (n = 57) conducted in men with BPH found a commercially available herbal formulation containing pumpkin seed oil, lycopene, saw palmetto, pygeum, and Epilobium parviflorum to significantly reduce median international prostate specific scores as well as day time and night time urinary frequency. Improvements were progressive and were observed in several scores at 1 month and in all scores at 3 months.57 The sponsor-funded PROCOMB Italian multicenter, double-blind, double-dummy, randomized trial determined that the combination of saw palmetto, lycopene, selenium (Profluss) plus tamsulosin produced significantly improved prostate symptom scores and Qmax (flow) after 1 year of treatment compared with Profluss or tamsulosin monotherapies in 219 men with BPH/lower urinary tract symptoms.58
Data suggesting a positive effect on erectile dysfunction are limited,5, 21 and results from studies evaluating the effect of saw palmetto on outcomes of transurethral resection of the prostate, particularly the bleeding complication, are equivocal.5, 23, 24
Guidelines have been published concerning the use of saw palmetto to treat lower urinary tract symptoms in men. The American Urological Association guidelines for the management of BPH (2011) conclude that the available data do not suggest that saw palmetto has a clinically meaningful effect on lower urinary tract symptoms secondary to BPH. The guidelines further state that the results of ongoing clinical trials will clarify the potential value of saw palmetto extract in the management of BPH.55 The European Association of Urology guidelines on the management of lower urinary tract symptoms in males (2013) discuss but do not make any specific recommendations on phytotherapy for the treatment of male lower urinary tract symptoms because of variability of products, lack of regulatory infrastructure, and variability in methodologies in the available literature. S. repens was not superior to placebo, finasteride, or tamsulosin with regard to the International Prostate Symptom Score.56
An increase in apoptosis has been documented in mice and in vitro studies.25, 26, 27 Prostate cancer cell proliferation was decreased in an in vitro experiment with saw palmetto berry extract, as well as with beta-sitosterol and stigmasterol.27, 28 No effect on human breast cancer cells was demonstrated.27 In addition, the radiosensitivity of normal prostate cells was increased with exposure to saw palmetto.29
Evidence from quality clinical studies is lacking.
A one-year randomized controlled trial comparing saw palmetto with finasteride for chronic prostatitis/chronic pelvic pain syndrome showed no improvement of the National Institute of Health Chronic Prostatitis Symptom Index score for the saw palmetto arm.62
Immunostimulatory activity has been shown in mice.2 Saw palmetto extracts reduced edema induced in the footpads of rats.12 Quality evidence is lacking to support a place in the treatment of alopecia6, 30 or acne.7
Crude saw palmetto berries are usually administered at a dosage of 1 to 2 g/day; however, lipophilic extracts standardized to 85% to 95% fatty acids in soft native extract or 25% fatty acids in a dry extract are more common.
Benign prostatic hyperplasia
Pregnancy / Lactation
Information regarding safety and efficacy in pregnancy and lactation is lacking. Because effects on androgen and estrogen metabolism have been identified, and there is no rationale for its use in pregnancy, saw palmetto should not be used in pregnancy or while breastfeeding2
Estrogen derivatives: Herbs (estrogenic properties) may enhance the adverse/toxic effect of estrogen derivatives. Monitor therapy.48
Use in children younger than 12 years is not recommended because of possible effects on androgen and estrogen metabolism.2 A case report exists of hot flashes in an 11-year-old girl using saw palmetto for hair loss.30
Cases of coagulopathies have been reported; however, the importance of anticoagulant effects is unclear and caution may be warranted.35, 38, 39, 40, 41 Case reports exist of acute pancreatitis,42, 43 rhabdomyolysis,44 acute hepatotoxicity,45 intraoperative floppy-iris syndrome,46 and hot flashes in an 11-year-old girl using saw palmetto.30
In the 2016 Scientific Statement by the American Heart Association regarding drugs that may cause or exacerbate heart failure, saw palmetto has been recognized as a product with antiplatelet activity which may increase bleeding risk when used with anticoagulants. The guidance noted that naturoceuticals are not recommended for the management of heart failure symptoms or for the secondary prevention of cardiovascular events, and that nutritional supplements are not recommended for the treatment of heart failure [Low-quality; Limited].60
Information is limited. A study in mice found that saw palmetto induced nuclear heterogeneity but not via DNA damage, thus the researchers did not consider it to be genotoxic.47 The relevance of these findings is unclear. No evidence of toxicity was found in the CAMUS clinical trial using 3 times the usual dosage over 18 months.37
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