Clinical effect of phytosterol-enriched saw palmetto extract on urinary function in healthy middle-aged and older males: a double-blind, placebo-controlled randomized comparative study


  • Tatsuya Hisajima
  • Hideaki Waki
  • Takuya Suzuki
  • Takashi Izumi



Background: Saw palmetto extract (SPE) is one of the most widely used supplements for benign prostatic hyperplasia (BPH) due to its pharmacological effects. β-sitosterol-enriched saw palmetto oil (VISPO™) contains more than 3% β-sitosterol and 85% total fatty acids and has been shown to improve symptoms in patients with BPH. Lower urinary tract symptoms (LUTS) require primary preventive measures in countries with accelerated population aging, including Japan. VISPO™ is expected to be effective against the early symptoms of LUTS. However, the effect of VISPO™ on urinary function in healthy individuals has not been elucidated.

Objective: This clinical study evaluated the efficacy and tolerability of VISPO™ in the management of urinary complaints among healthy middle-aged and older men who did not require treatment.

Methods: We conducted a randomized, double-blind, placebo-controlled trial that included 54 male participants who were assigned to consume VISPO™ or placebo (olive oil) capsules for 12 weeks. Biometric data, uroflowmetry results, and salivary hormone levels were assessed at weeks 1 and 12. Urinary function and quality of life were assessed at weeks 1, 4, 8, and 12 using the International Prostate Symptom Score (IPSS), Overactive Bladder Symptom Score (OABSS), Core Lower Urinary Tract Symptom Score (CLSS), and WHOQOL-26.

Results: Two-way analysis of variance revealed that IPSS and OABSS were significantly lower in the VISPO™ group that in the placebo group. However, there were no significant differences in urine volume, urinary flow rate, or salivary hormone levels. In addition, no participants reported adverse effects (diarrhea, abdominal pain, etc.). 

Conclusion: The results of the present study, which is the first randomized controlled trial of VISPO™ conducted among healthy participants, demonstrate the effectiveness of VISPO™ in the management of lower urinary tract complaints that do not require treatment. 

Trial Registration: University Hospital Medical Information Network Clinical Trials Registry (UMIN000046386).

Keywords: saw palmetto, VISPO™, β-sitosterol, fatty acids, healthy subjects, primary preventive, IPSS, OABSS, lower urinary tract symptoms (LUTS)





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