Not meaningfully. The two largest placebo-controlled trials — STEP in 2006 and the NIH-funded CAMUS trial in 2011, which used up to 960 mg a day for 72 weeks — found saw palmetto no better than placebo for urinary symptoms, flow rate or prostate size. The 2023 Cochrane review of 27 trials found an average symptom-score improvement of under one point, below what a man can perceive. A specific hexane extract sold as a medicine in Europe has modest positive results of its own. Saw palmetto is safe, so trying it does little harm; relying on it delays treatments that work.
The verdict, in three numbers
Saw palmetto has been tested harder than almost any herb, and the decisive results fit in a sentence each: STEP (2006) found a year of the standard dose indistinguishable from placebo on every measure; the NIH's CAMUS trial (2011) tripled the dose for 72 weeks and placebo beat it, 3.0 symptom points to 2.2; and the 2023 Cochrane review of 27 trials put the pooled advantage at 0.9 points — a third of the smallest change a man can feel — with high certainty and no effect on flow or prostate size.
The pre-2006 positive studies were the small, short, weakly blinded kind that a fluctuating, placebo-responsive symptom rewards — the classic early-supplement trajectory. The one partial exception, Europe's hexane-extracted Permixon with its own modest manufacturer-funded trials, is not the extract in the bottles most men buy. The full trial history, the extract chemistry and the uses beyond the prostate are on the saw palmetto ingredient page; this page's job is the decision.
What works instead
Men with bothersome urinary symptoms have options with strong evidence:
- Lifestyle measures — evening fluid restriction, less caffeine and alcohol, double voiding, treating constipation, reviewing medications — help at any stage and cost nothing.
- Alpha-blockers (tamsulosin and others) improve symptoms within days.
- 5-alpha reductase inhibitors (finasteride, dutasteride) shrink the gland over months and reduce the risk of retention.
- Minimally invasive procedures and surgery for symptoms that persist.
And a doctor's assessment excludes the other causes of a weak stream or night-time urination that a supplement would not address — infection, stricture, an underactive bladder, or urine produced in excess overnight.
If you still want to try a supplement
Beta-sitosterol at 60–130 mg a day has a small body of older trials showing improved symptoms and flow — better evidence than saw palmetto, though dated. Either is safe. Neither affects PSA. Tell your doctor, set a time limit of a few months, keep a symptom score, and stop if nothing has changed. Our prostate supplement research pages evaluate the commercial products that combine these ingredients.
Frequently asked questions
Why do so many men say it helped them?
Urinary symptoms fluctuate and tend to improve with attention to fluids and habits, and the placebo response in BPH trials is large — placebo groups routinely improve by 2–3 symptom points. A man who starts saw palmetto and improves has no way of knowing whether the supplement did it. That is what randomized trials are for, and they say it did not.
Did the trials use the wrong kind of saw palmetto?
This is the main defence, and it has some merit for the specific hexane extract used in European trials. It does not rescue the products most men buy, which are not that extract, and CAMUS used a well-characterized extract at high dose.
What about combination prostate supplements?
Adding beta-sitosterol, pygeum, nettle, zinc or lycopene to saw palmetto does not create evidence that the combination works; each has weaker evidence than saw palmetto's negative trials. Beta-sitosterol alone has some old positive trials.
Is there any harm in trying it?
Little direct harm — it is well tolerated and does not affect PSA. The harm is indirect: months on an ineffective supplement while symptoms progress, and money that could have gone to a doctor's visit.
References
- JAMA. Effect of increasing doses of saw palmetto extract on lower urinary tract symptoms: a randomized trial (CAMUS) (2011). PubMed PMID 21954478. https://pubmed.ncbi.nlm.nih.gov/21954478/
- National Center for Complementary and Integrative Health. Saw Palmetto: Usefulness and Safety (2024). https://www.nccih.nih.gov/health/saw-palmetto
- NIDDK. Prostate Enlargement (Benign Prostatic Hyperplasia) (2024). https://www.niddk.nih.gov/health-information/urologic-diseases/prostate-problems/prostate-enlargement-benign-prostatic-hyperplasia
This page discusses supplement ingredients or categories. It may mention a commercial product, with disclosure. It is general health information, not personal medical advice. Read our editorial policy and medical review policy.