Mixed sterols, particularly beta-sitosterol, are plant-derived compounds structurally similar to cholesterol. There is moderate scientific evidence supporting their use for prostate health, specifically in alleviating lower urinary tract symptoms (LUTS) associated with benign prostatic hyperplasia (BPH), a common condition in older men. Several randomized, placebo-controlled clinical trials and meta-analyses have evaluated the effect of beta-sitosterol and mixed plant sterols on symptoms such as urinary flow and residual urine volume.

A 1999 meta-analysis published in the journal JAMA reviewed four randomized, placebo-controlled, double-blind studies (totaling 519 men) and found that beta-sitosterol improved urinary symptom scores and flow measures compared to placebo. Other systematic reviews have confirmed modest but statistically significant improvements. However, these studies typically used standardized, purified beta-sitosterol preparations, and the duration of treatment was usually short-term (4-26 weeks). Evidence on long-term safety and efficacy is limited, and sterols do not reduce prostate size.

The exact mechanism is not fully understood, but sterols may exert anti-inflammatory effects or influence cell signaling in the prostate. Despite some positive findings, leading medical guidelines consider the evidence insufficient to recommend sterols as first-line therapy for BPH, though they are often used as complementary agents. Overall, the scientific evidence supporting mixed sterols for prostate health is moderate (rated 3/5).