Health Care Professional Information
American dwarf palm tree, cabbage palm
Saw palmetto is a small, slow-growing palm native to southeastern United States. The fruits are a rich source of fatty acids and phytosterols and have been used to promote urination, reduce inflammation, and for treatment of prostatic conditions such as benign prostatic hyperplasia (BPH).
Saw palmetto has been studied in many controlled clinical trials. Whereas data from some studies indicate that it improves lower urinary tract symptoms in patients with benign prostatic hyperplasia (2) (3) (4) (5) (15) (17) (18) (26), conflicting data suggest no such effects (6) (14) (19) (28). A recent study showed that saw palmetto may benefit patients with chronic bacterial prostatitis when coadministered with Urtica dioica, curcumin and quercitin (16). Pretreatment with saw palmetto reduced intra- and postoperative complications in patients who underwent transurethral resection of the prostate and open prostatectomy (22). However, saw palmetto use was not associated with risk of prostate cancer (27).
Saw palmetto extract was found to inhibit growth of normal prostate cells and increase their sensitivity to radiation in vitro, but did not affect malignant prostate cancer cells (20). Due to the increased risk of normal tissue complications, patients should consult with a physician before using saw palmetto supplements during radiation therapy. There is an ongoing study to determine the effects of saw palmetto on symptom management during radiation therapy.
- Benign prostatic hypertrophy (BPH)
- Promote urination
- Prostate cancer
- Fatty Acids: Capric, caprylic, lauric, cis-linoleic, myristic, palmitic and stearic acid
- Steroids: beta-sitosterol, campesterol, cycloartenol, lupeol, lupenone and stigmasterol
- Aliphatic alcohols
- Polyprenic compounds: Arabinose, flavonoids, galactose, glucose and uronic acid
- Anthranilic acid
Mechanism of Action
Studies with a liposterolic extract of saw palmetto berries showed that it reduced the uptake by tissue specimens of both testosterone and dihydrotestosterone (DHT) by more than 40% suggesting antiandrogenic activity (7). Further, the extract inhibited binding of DHT to its receptor (8) and blocked the conversion of testosterone to DHT by inhibiting the activity of 5-alpha-reductase (9). The berries also inhibit cyclooxygenase and 5-lipoxygenase pathways, thereby preventing the biosynthesis of inflammation-producing prostaglandins and leukotrienes (10).
Analysis of saw palmetto components including lauric acid, oleic acid, and beta-sitosterol in rats revealed wide distribution. Highest concentrations were found in abdominal fat, prostate, and skin, while lesser amounts were found in bladder and liver.
- Although infrequent, saw palmetto may cause intraoperative hemorrhage, GI complaints, nausea, vomiting, and diarrhea. It may also have additive anticoagulant effects and prolong bleeding time (11).
- A case of severe intraoperative hemorrhage following consumption of saw palmetto has been reported (11).
- Hematuria and coagulopathy were observed in a patient with use of saw palmetto (21).
- Acute pancreatitis was reported in a 65-year-old male following use of saw palmetto for one week before onset of symptoms. His condition improved after treatment and avoiding saw palmetto (23).
- A 58-year-old man experienced severe liver damage following consumption of saw palmetto to alleviate symptoms of BPH. His symptoms improved after discontinuing saw palmetto (24).
- Anticoagulants: Saw palmetto may have additive anticoagulant effect (11).
- UGT (Uridine 5'-diphospho-glucuronosyltransferase) substrates: Saw palmetto inhibits UGT enzymes in vitro and can increase the side effects of drugs metabolized by them (25).
- CYP 450 substrates: Saw palmetto inhibits cytochrome P450 3A4, 2D6, and 2C9 and may interfere with the actions of drugs metabolized by these enzymes (29)
Herb Lab Interactions
- May prolong bleeding time. (11)
- No significant change in mean serum PSA noted. (3)
Literature Summary and Critique
Bent S, et al. Saw Palmetto for Benign Prostatic Hyperplasia. N Engl J Med 2006; 354(6): 557- 566.
Two hundred and twenty-five men (over the age of 49 years) with moderate-to-severe symptoms of benign prostatic hyperplasia (BPH) were randomized to receive saw palmetto extract (160 mg twice a day) or placebo for one year. There was no significant difference in the primary outcome measures — the American Urological Association Symptom Index (AUASI) scores or the maximal urinary flow rates between patients taking saw palmetto or placebo. Also, no significant differences were observed in prostate size, residual volume after voiding, quality of life, or serum PSA levels between the two groups.
These data contradict several earlier studies in which saw palmetto appeared to be a promising alternative for BPH. Researchers point to the methodological flaws in those studies, including shorter duration of study, failure to use validated symptom scores, and ineffective blinding.
Dosage (Inside MSKCC Only)
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- Feifer AH, Fleshner NE, Klotz L. Analytical accuracy and reliability of commonly used nutritional supplements in prostate disease. J Urol 2002;168:150-4.
- Fagelman E, Lowe FC. Herbal medications in the treatment of benign prostatic hyperplasia (BPH). Urol Clin N Am 2002;29:23-9.
- Gerber G, et al. Saw palmetto (Serenoa repens) in men with lower urinary tract symptoms: effects on urodynamic parameters and voiding symptoms. Urology. 1998 Jun;51(6):1003-7.
- Boyle P, Robertson C, Lowe F, et al. Meta-analysis of clinical trials of permixon (saw palmetto) in the treatment of symptomatic benign prostatic hyperplasia. Urology 2000;55:533-9.
- Wilt TJ, Ishani A, Start G, et al. Saw palmetto extracts for treatment of benign prostatic hyperplasia: a systematic review. JAMA 1998;280:1604-9.
- Bent S, et al. Saw palmetto for benign prostatic hyperplasia. N Engl J Med 2006;354(6): 557-566.
- El-Sheikh MM, Dakkak MR, and Saddique A. The effect of Permixon on androgen receptors. Acta Obstet Gynecol Scand. 1988;67(5):397-9.
- Carilla E, Briley M, Fauran F, et al. Binding of Permixon, a new treatment for prostatic benign hyperplasia, to the cytosolic androgen receptor in the rat prostate.J Steroid Biochem 1984;20(1):521-3.
- Bayne CW, Donnelly F, Ross M, Habib FK. Serenoa repens (Permixon): a 5alpha-reductase types I and II inhibitor-new evidence in a coculture model of BPH. Prostate 1999;40(4):232-41.
- 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;25:1117-24.
- Cheema P, El-Mefty O, Jazieh AR, et al. Intraoperative haemorrhage associated with the use of extract of Saw Palmetto herb: a case report and review of literature. J Intern Med. 2001 Aug;250(2):167-9.
- Newall C, Herbal Medicines: A Guide for Health-Care Professionals. London: Pharmaceutical Press; 1996.
- Chevalier G, et al. Distribution study of radioactivity in rats after oral administration of the lipido/sterolic extract of serenoa repens supplemented with [1-14C]-lauric acid, [1-14C]-oleic acid or [4-14C]-beta-sitosterol. Eur J Drug Metab Pharmacokinet 1997;22:73-83.
- Avins AL, Bent S, Staccone S, et al. A detailed safety assessment of a saw palmetto extract.Complement Ther Med. 2008 Jun;16(3):147-54.
- Shi R, Xie Q, Gang X, et al. Effect of saw palmetto soft gel capsule on lower urinary tract symptoms associated with benign prostatic hyperplasia: a randomized trial in Shanghai, China. J Urol. 2008 Feb;179(2):610-5.
- Cai T, Mazzoli S, Bechi A, et al. Serenoa repens associated with Urtica dioica (ProstaMEV) and curcumin and quercitin (FlogMEV) extracts are able to improve the efficacy of prulifloxacin in bacterial prostatitis patients: results from a prospective randomised study. Int J Antimicrob Agents. 2009 Jun;33(6):549-53.
- Lopatkin N, Sivkov A, Schläfke S, et al. Efficacy and safety of a combination of Sabal and Urtica extract in lower urinary tract symptoms—long-term follow-up of a placebo-controlled, double-blind, multicenter trial. Int Urol Nephrol. 2007;39(4):1137-46.
- Hizli F, Uygur MC. A prospective study of the efficacy of Serenoa repens, tamsulosin, and Serenoa repens plus tamsulosin treatment for patients with benign prostate hyperplasia. Int Urol Nephrol. 2007;39(3):879-86.
- Tacklind J, MacDonald R, Rutks I, Wilt TJ. Serenoa repens for benign prostatic hyperplasia. Cochrane Database of Systematic Reviews 2009, Issue 2. Art. No.: CD001423. DOI: 10.1002/14651858.CD001423.pub2.
- Hasan Y, Schoenherr D, Martinez AA, et al. Prostate-specific natural health products (dietary supplements) radiosensitize normal prostate cells. Int J Radiat Oncol Biol Phys. 2010 Mar 1;76(3):896-904.
- Villanueva S, González J. Coagulopathy induced by saw palmetto: a case report. Bol Asoc Med P R. 2009 Jul-Sep;101(3):48-50.
- Anceschi R, Bisi M, Ghidini N, Ferrari G, Ferrari P. Serenoa repens (Permixon) reduces intra- and postoperative complications of surgical treatments of benign prostatic hyperplasia. Minerva Urol Nefrol. 2010 Sep;62(3):219-23.
- Wargo KA, Allman E, Ibrahim F. A possible case of saw palmetto-induced pancreatitis. South Med J. 2010 Jul;103(7):683-5.
- Lapi F, Gallo E, Giocaliere E, et al. Acute liver damage due to Serenoa repens: a case report. Br J Clin Pharmacol. 2010 May;69(5):558-60.
- Mohamed ME, Frye RF. Inhibitory Effects of Commonly Used Herbal Extracts on UGT1A4, 1A6, and 1A9 Enzyme Activities. Drug Metab Dispos. 2011 Jun 1. [Epub ahead of print]
- Sinescu I, Geavlete P, Multescu R, et al. Long-term efficacy of Serenoa repens treatment in patients with mild and moderate symptomatic benign prostatic hyperplasia. Urol Int. 2011;86(3):284-9. Epub 2011 Feb 8.
- Brasky TM, Kristal AR, Navarro SL, et al. Specialty supplements and prostate cancer risk in the VITamins and Lifestyle (VITAL) cohort. Nutr Cancer. 2011 May;63(4):573-82.
- Barry MJ, Meleth S, Lee JY, et al. Effect of Increasing Doses of Saw Palmetto Extract on Lower Urinary Tract Symptoms. A Randomized Trial. JAMA. 2011;306(12):1344-1351.
- 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 Jun;11(3):433-9.
How It Works
Bottom Line: Saw palmetto was shown in some studies to help relieve the symptoms of benign prostatic hypertrophy (BPH), but it has not been shown to prevent or treat prostate cancer.
Studies in the laboratory and in animals show that saw palmetto works by countering the effects of androgens (the male sex hormones), such as testosterone and DHT. It is thought that saw palmetto does not reduce the levels of these hormones circulating in the blood, but causes body tissues (like the prostate) to take in lower levels of the hormones. Other studies have noted that saw palmetto reduces the conversion of testosterone to the DHT, its more potent form, by inhibiting the enzyme 5 alpha reductase. Saw palmetto berry extracts also reduce inflammation and edema in laboratory studies by inhibiting the formation of compounds that cause these reactions.
In a lab study, saw palmetto extract was found to slow the growth of normal prostate cells and increase their sensitivity to radiation, while not affecting prostate cancer cells. Since this may increase the risk of complications, patients should consult with a physician before using saw palmetto supplements during radiation therapy.
- To treat benign prostatic hypertrophy (BPH)
Several clinical trials and meta-analyses have shown that saw palmetto improves urinary tract symptoms associated with BPH.
- To treat prostate cancer
Saw palmetto shows anti-inflammatory and anti-androgen properties in laboratory studies and reduces the levels of DHT in the prostate in clinical trials.
- As a diuretic
No scientific evidence supports this use.
- As an anti-inflammatory
Laboratory studies support this use, but human data are lacking.
Benign prostatic hypertrophy (BPH)
Two hundred and twenty-five men (over the age of 49 years) with moderate-to-severe symptoms of benign prostatic hyperplasia (BPH) were given saw palmetto extract (160 mg twice a day) or placebo for one year. There was no significant difference in the American Urological Association Symptom Index (AUASI) scores or the maximal urinary flow rates between patients taking saw palmetto or placebo. Also, no significant differences were observed in prostate size, quality of life, or serum prostate specific antigen (PSA) levels between the two groups.
Do Not Take If
- You are taking warfarin or other blood thinners (Saw palmetto may increase the risk of bruising and bleeding).
- You are taking drugs that are substrates of UGT (Uridine 5'-diphospho-glucuronosyltransferase) enzymes (Saw palmetto may increase the risk of side effects of these drugs).
- Gastrointestinal complaints: nausea, vomiting, and diarrhea
- Saw palmetto may have additive anticoagulant effects and prolong bleeding time.
- A case of severe intraoperative hemorrhage following consumption of saw palmetto has been reported.
- Hematuria and coagulopathy were observed in a patient with use of saw palmetto.
- Acute pancreatitis was reported in a 65-year-old male following use of saw palmetto for one week before onset of symptoms. His condition improved after treatment and avoiding saw palmetto.
- A 58-year-old man experienced severe liver damage following consumption of saw palmetto to alleviate symptoms of BPH. His symptoms improved after discontinuing saw palmetto.
Last updated: September 29, 2012