Saw Palmetto for Benign Prostatic Hyperplasia
Saw palmetto should not be recommended for the treatment of lower urinary tract symptoms (LUTS) attributed to benign prostatic hyperplasia (BPH), as high-quality evidence demonstrates it is no more effective than placebo. 1
Evidence Against Efficacy
The most rigorous evidence comes from a well-designed, double-blind, placebo-controlled trial of 225 men with moderate-to-severe BPH symptoms treated for one year with saw palmetto extract (160 mg twice daily). 1 This study found:
- No significant difference in American Urological Association Symptom Index (AUASI) scores between saw palmetto and placebo (mean difference 0.04 points) 1
- No improvement in maximal urinary flow rate (mean difference 0.43 ml/min) 1
- No changes in prostate size, post-void residual volume, quality of life, or PSA levels 1
- Similar side effect profiles between groups 1
This contradicts the widespread use of saw palmetto by over 2 million men in the United States who take it as an alternative to FDA-approved medications. 1
Guideline-Recommended Treatment Approach
Current AUA guidelines for LUTS/BPH management do not include saw palmetto as an acceptable treatment option. 2 Instead, evidence-based medical therapy includes:
First-Line Medical Therapy
- Alpha-adrenergic antagonists (alpha blockers) as initial therapy for symptomatic relief 2
- If prostate volume exceeds 30cc, consider adding a 5-alpha reductase inhibitor (5ARI) 2
- For patients with concomitant erectile dysfunction, phosphodiesterase-5 inhibitors (PDE5s) may be initiated as first-line therapy 2
Follow-Up Strategy
- Patients should be evaluated 4-12 weeks after initiating treatment to assess response using the International Prostate Symptom Score (IPSS) 2
- Further evaluation may include post-void residual (PVR) and uroflowmetry 2
- Patients without symptom improvement or experiencing intolerable side effects should undergo further evaluation and consideration of alternative medical management or surgical intervention 2
Why Saw Palmetto Appears to Work Despite Lack of Efficacy
The perceived benefit of saw palmetto likely reflects the profound placebo effect well-recognized in LUTS treatment trials, making placebo-controlled studies imperative for evaluating any BPH therapy. 3 Some open-label, uncontrolled studies have suggested benefits, 4 but these lack the rigor necessary to distinguish true efficacy from placebo response.
Potential Safety Concerns
While generally considered well-tolerated, saw palmetto is not without risk:
- Case reports of acute pancreatitis have been documented, potentially related to its estrogenic receptor stimulation or cyclooxygenase inhibition 5
- Hepatotoxicity has been reported, possibly related to its estrogen/antiandrogen properties 5
- The lack of standardized formulations contributes to inconsistent results across studies 6
Clinical Recommendation Algorithm
When a patient presents with bothersome LUTS possibly attributed to BPH:
- Obtain medical history, physical examination including digital rectal exam (DRE), IPSS score, and urinalysis 2
- Counsel on evidence-based options: behavioral/lifestyle modifications, medical therapy (alpha blockers ± 5ARIs), or procedural interventions 2
- Do not recommend saw palmetto as it lacks proven efficacy beyond placebo 1
- If patient insists on trying saw palmetto despite counseling, inform them of the lack of evidence and potential risks, and ensure close follow-up 1, 5
Common Pitfall to Avoid
Do not assume that because saw palmetto is "natural" or widely used that it is effective. The popularity of complementary and alternative medicines does not substitute for rigorous evidence of efficacy. 3 Patients choosing saw palmetto over proven therapies may experience disease progression, including increased risk of acute urinary retention, which rises from 6.8 episodes per 1,000 patient-years in the general population to 34.7 episodes in men aged 70 and older. 2