Phytosterols, plant-derived sterols structurally similar to cholesterol, are widely researched for their role in supporting prostate health, particularly in the context of benign prostatic hyperplasia (BPH), a non-cancerous enlargement of the prostate gland common in older men. Multiple randomized, placebo-controlled clinical trials, as well as meta-analyses, have demonstrated that phytosterol supplementation (often as beta-sitosterol or plant sterol mixtures) can modestly improve urinary symptoms and flow measures in men with BPH. Notably, a 1995 study published in The Lancet and a 2000 meta-analysis in the journal Cochrane Database of Systematic Reviews both found significant improvement in symptoms such as urinary frequency, nocturia, and peak urine flow rates compared to placebo.

The mechanism is thought to involve inhibition of 5-alpha-reductase (an enzyme that converts testosterone to dihydrotestosterone, which stimulates prostate growth), anti-inflammatory effects, and improvement in cholesterol metabolism within prostate tissues. While phytosterols do not shrink the prostate or cure BPH, their symptom-relieving effects appear consistent and clinically meaningful for some men. That said, long-term safety and efficacy data are limited, and phytosterols should not replace medical evaluation or treatment for prostate conditions. Overall, the evidence supporting phytosterols for prostate symptom relief is robust compared to many other dietary supplements, justifying their inclusion as a supportive measure for prostate health.