Clinical Question: Does saw palmetto improve symptoms of benign prostatic hyperplasia?

Setting: Outpatient (specialty)

Study Design: Randomized controlled trial (double-blinded)

Allocation: Concealed

Synopsis: Previous smaller studies of saw palmetto consistently have found a benefit in patients with benign prostatic hyperplasia, but blinding may have been inadequate given the bitter taste of the product. The studies also were of relatively short duration and did not consistently use a validated symptom scale.

In this study, men with moderate to severe benign prostatic hyperplasia (i.e., American Urology Association [AUA] symptom index of 8 or higher and a urinary flow rate of less than 15 mL per second) were recruited from the community. A one-month placebo run-in period was done to exclude nonadherent men. The remaining 225 men were then randomized (allocation concealed) to one year of treatment with saw palmetto extract at a dosage of 160 mg twice daily or a placebo designed to match the active drug in taste. Five patients in each group discontinued the intervention, and four from one group and five from the other were lost to follow-up.

Analysis was by intention to treat. At the end of the study, there was no difference between groups on the AUA symptom index score for urinary f low rate, sexual function, serum creatinine level, prostate-specific antigen, or any other outcome measure. The 95% confidence interval for the change (or lack thereof) in AUA symptom index score was only one point on a 35-point scale, so it is unlikely that the study failed to detect a clinically meaningful improvement because of lack of sample size. Subgroup analyses also found no benefit among patients with more or less severe symptoms or among patients with smaller or larger prostates. These results differ from the Cochrane review on the topic that included 21 clinical trials and found a mean improvement of 1.4 on a 19-point symptom scale and just less than one fewer episode of urination per night.

Bottom Line: The authors of this rigorously designed trial found that saw palmetto produces no improvement in symptoms for men with moderate to severe benign prostatic hyperplasia, a finding that differs from the bulk of the previous literature. (Level of Evidence: 1b)