The berries of the saw palmetto plant are used to treat symptoms associated with benign prostatic hyperplasia (BPH). Saw palmetto, or Serenoa repens, is a small palm native to the southeastern United States, especially Florida and nearby coastal regions. Its ripe fruits contain fatty acids and phytosterols and are made into extracts marketed for urinary symptoms caused by an enlarged prostate.
BPH is a noncancerous enlargement of the prostate that can produce a weak urine stream, urgency, frequent urination, or difficulty emptying the bladder. Saw palmetto is often discussed alongside prescription 5-alpha-reductase inhibitors because laboratory research suggested it might affect androgen pathways, including conversion of testosterone to dihydrotestosterone.
A common mix-up is confusing saw palmetto with pygeum, which comes from the bark of an African tree, or stinging nettle, for which the root is used. The fact that saw palmetto is marketed for BPH does not mean it is proven to work: large trials and reviews have generally found little or no benefit over placebo.