Saw palmetto (Serenoa repens) is commonly used to support urinary and bladder health, especially in men with lower urinary tract symptoms (LUTS) associated with benign prostatic hyperplasia (BPH). The use of saw palmetto for urinary symptoms has historical roots in traditional medicine among Native American populations, but it is primarily justified today by scientific studies focused on its effects on the prostate and urinary function.

Several clinical trials and systematic reviews have evaluated saw palmetto extract for its ability to improve urinary flow, reduce nocturia (nighttime urination), and decrease the sensation of incomplete bladder emptying in men with BPH. Proposed mechanisms include inhibition of 5-alpha-reductase (an enzyme that converts testosterone to dihydrotestosterone), anti-inflammatory effects, and relaxation of smooth muscle in the urinary tract.

However, the quality of evidence is mixed. Some studies and meta-analyses report modest improvements in urinary symptoms compared to placebo, while others find no significant benefit. The American Urological Association and other professional bodies acknowledge the widespread use of saw palmetto but generally consider the evidence insufficient to recommend it as a first-line therapy for BPH-related urinary symptoms.

In summary, saw palmetto has some scientific support for its use in supporting the bladder and lower urinary tract, particularly in the context of BPH, though the overall evidence is moderate and somewhat inconsistent.