Beta-sitosterol is a plant-derived sterol commonly used to support the urinary system, particularly in the context of benign prostatic hyperplasia (BPH), a non-cancerous enlargement of the prostate gland which can affect urinary function in men. Several clinical trials and systematic reviews have evaluated the efficacy of beta-sitosterol for this purpose. A meta-analysis published in the journal British Journal of Urology (Wilt et al., 1999) reviewed randomized, placebo-controlled, double-blind trials and found that beta-sitosterol improved urinary symptoms and flow measures in men with mild to moderate BPH compared to placebo. Improvements were noted in parameters such as urinary flow rate and the reduction of residual urine volume, both of which are relevant to urinary health. However, the studies reviewed were of relatively short duration and did not provide evidence regarding long-term safety or the ability to reduce prostate size.

The mechanism of action appears to be unrelated to hormonal pathways; instead, beta-sitosterol may exert anti-inflammatory and immune-modulatory effects on the prostate and urinary tract. While these results are promising, beta-sitosterol does not cure BPH and should not be considered a replacement for medical treatment in severe cases. Overall, there is moderate scientific evidence supporting the use of beta-sitosterol for urinary symptoms associated with BPH, warranting a rating of 3 out of 5.