Plant sterols, particularly beta-sitosterol, are supported by scientific evidence for their role in supporting prostate health, particularly in the context of benign prostatic hyperplasia (BPH), a common non-cancerous enlargement of the prostate in older men. Multiple randomized, placebo-controlled clinical trials have demonstrated that plant sterol supplementation can significantly improve urinary symptoms associated with BPH, such as flow rate and residual urine volume. The proposed mechanism is that plant sterols may inhibit 5-alpha-reductase, reducing the conversion of testosterone to dihydrotestosterone (DHT), a hormone implicated in prostate growth. Meta-analyses, including a 2000 review in The Lancet, concluded that beta-sitosterol improves urinary symptoms and flow measures compared to placebo, although effects on prostate size are less clear. Plant sterols are included in several evidence-based guidelines as a non-pharmaceutical option for BPH symptom management. While not a cure, and not all men respond, the overall evidence base is relatively strong among dietary supplements for the prostate, warranting a score of 4 out of 5 for scientific support. Importantly, plant sterols are not used for prostate cancer prevention or treatment, and their role is specific to symptom management in BPH.