Objectives: To conduct a systematic review of the evidence for the efficacy of beta-sitosterol in men with symptomatic benign prostatic hyperplasia (BPH).

Methods: Studies were identified through Medlinetrade mark (1966-98), EMBASEtrade mark, Phytodok, the Cochrane Library, bibliographies of identified trials and review articles, and contact with study authors and pharmaceutical companies. Randomized trials were included if: men had symptomatic BPH; plant extract preparations contained beta-sitosterols; a control group received placebo or a pharmacological therapy; and treatment duration was >/=30 days. Study characteristics, demographic information, enrolment criteria and outcomes were extracted.

Results: Four trials comprising a total of 519 men met the inclusion criteria. All were double-blind and lasted 4-26 weeks. Three studies used nonglucosidic beta-sitosterols and one used a preparation that contained only beta-sitosterol-beta-d-glucoside. Compared with placebo, beta-sitosterol improved urinary symptom scores and flow measures. For the two studies reporting the International Prostate Symptom Score (IPSS), the weighted mean difference (WMD) against placebo was -4.9 IPSS points (95% confidence interval, CI,-6.3 to-3.5). The WMD for peak urinary flow rate was 3.91 mL/s (95% CI 0.91 to 6.90, four studies) and for residual volume the WMD was -28.62 mL (95% CI-41.42 to-15.83, four studies). beta-sitosterol did not reduce prostate size. The trial using pure beta-sitosterol-beta-d-glucoside (WA184) showed no improvement in urinary flow measures. Withdrawal rates for men assigned to beta-sitosterol and placebo were 7.8% and 8.0% (not significant), respectively.

Conclusion: beta-sitosterol improves urological symptoms and flow measures. However, the existing studies are limited by short treatment duration and lack of standardized beta-sitosterol preparations. Their long-term effectiveness, safety and ability to prevent the complications of BPH are unknown.