Effect of increasing doses of saw palmetto extract on lower urinary tract symptoms: a randomized trial

Abstract

Context: Saw palmetto fruit extracts are widely used for treating lower urinary tract symptoms attributed to benign prostatic hyperplasia (BPH); however, recent clinical trials have questioned their efficacy, at least at standard doses (320 mg/d).

Objective: To determine the effect of saw palmetto extract (Serenoa repens, from saw palmetto berries) at up to 3 times the standard dose on lower urinary tract symptoms attributed to BPH.

Design, setting, and participants: A double-blind, multicenter, placebo-controlled randomized trial at 11 North American clinical sites conducted between June 5, 2008, and October 10, 2010, of 369 men aged 45 years or older, with a peak urinary flow rate of at least 4 mL/s, an American Urological Association Symptom Index (AUASI) score of between 8 and 24 at 2 screening visits, and no exclusions.

Interventions: One, 2, and then 3 doses (320 mg/d) of saw palmetto extract or placebo, with dose increases at 24 and 48 weeks.

Main outcome measures: Difference in AUASI score between baseline and 72 weeks. Secondary outcomes included measures of urinary bother, nocturia, peak uroflow, postvoid residual volume, prostate-specific antigen level, participants' global assessments, and indices of sexual function, continence, sleep quality, and prostatitis symptoms.

Results: Between baseline and 72 weeks, mean AUASI scores decreased from 14.42 to 12.22 points (-2.20 points; 95% CI, -3.04 to -1.36) [corrected]with saw palmetto extract and from 14.69 to 11.70 points (-2.99 points; 95% CI, -3.81 to -2.17) with placebo. The group mean difference in AUASI score change from baseline to 72 weeks between the saw palmetto extract and placebo groups was 0.79 points favoring placebo (upper bound of the 1-sided 95% CI most favorable to saw palmetto extract was 1.77 points, 1-sided P = .91). Saw palmetto extract was no more effective than placebo for any secondary outcome. No clearly attributable adverse effects were identified.

Conclusion: Increasing doses of a saw palmetto fruit extract did not reduce lower urinary tract symptoms more than placebo.

Trial registration: clinicaltrials.gov Identifier: NCT00603304.

Figure 1

CONSORT diagram for the trial

Figure 3

Comparisons of the difference between group mean AUASI score changes from baseline to 72 weeks for the saw palmetto and placebo groups stratified by select baseline variables (continuous variables dichotomized at the median) in the modified intention to treat population. The subgroup analysis by race was prespecified in the study protocol; the rest are exploratory post hoc analyses. (P values based on a test for interaction in the primary analysis.)