Saw palmetto for the prostate: what the evidence shows

Large, well-run trials found that saw palmetto alone does little or nothing for urinary symptoms of an enlarged prostate. A 2023 Cochrane review concluded that it provides little to no benefit for men with these symptoms, and NCCIH says saw palmetto is probably not helpful for this purpose. The evidence is less clear for saw palmetto combined with other herbs, which is how most prostate supplements are sold.

Below is what the big trials measured, what the doses were, what it means when a label shows a smaller amount or no amount at all, and what to do if you have urinary symptoms.

What is saw palmetto used for?

Saw palmetto is a small palm native to the West Indies and the southeast coast of North America. NCCIH says its berries are promoted as a dietary supplement for urinary symptoms linked to an enlarged prostate, known as benign prostatic hyperplasia or BPH. It is also promoted for male pattern baldness and for chronic prostatitis and pelvic pain.

BPH is very common. MedlinePlus says prostate enlargement happens to almost all men as they get older, that a small amount is present in many men over 40, and that more than 90% of men over 80 have it. It is not cancer and does not raise the risk of prostate cancer. MedlinePlus also notes that fewer than half of men with BPH have symptoms. Those symptoms include a weak stream, dribbling, needing to urinate two or more times a night, and feeling that the bladder is not empty.

What did the biggest trial find?

The trial most often cited is the CAMUS trial, funded by the NIH and published in JAMA in 2011. It was double-blind and placebo-controlled, with 369 men aged 45 or older who had urinary symptoms attributed to BPH. The men took saw palmetto extract or placebo for 72 weeks. The standard dose is 320 mg a day. The researchers gave one dose for the first 24 weeks, then two doses, then three doses (up to 960 mg a day) after week 48.

The results were clear. Symptom scores fell in both groups. They dropped by 2.20 points with saw palmetto and by 2.99 points with placebo. The difference was 0.79 points in favor of placebo. Saw palmetto was no more effective than placebo on any secondary outcome, including nighttime urination, urine flow and bother from symptoms. No clearly attributable side effects were found.

The authors' conclusion was that increasing doses of a saw palmetto fruit extract did not reduce urinary symptoms more than placebo. The trial was designed to answer an earlier objection, that standard doses might be too low. Tripling the dose changed nothing.

What do the pooled reviews say?

The 2023 Cochrane review, an update of an earlier version, included 27 studies with 4,656 participants. Nineteen compared saw palmetto with placebo, and eight tested saw palmetto in combination with other herbs versus placebo. Ten of the studies were funded by the pharmaceutical industry and two by government agencies.

For saw palmetto alone, in studies at low risk of bias, the review found little to no difference in urinary symptoms at 3 to 6 months, and again at 12 to 17 months. Both were rated high-certainty evidence. It found little to no difference in quality of life. Adverse events probably did not differ from placebo. The authors concluded that Serenoa repens alone provides little to no benefit for men with lower urinary tract symptoms due to benign prostatic enlargement.

NCCIH's summary agrees. It describes the 2023 review of 27 studies, notes that the two NIH-funded trials were included, and says the researchers found no difference between hexane-extracted products and other extracts. NCCIH adds that a 2022 review of five studies on saw palmetto for chronic prostatitis and pelvic pain did not find a significant benefit.

Question	Finding	Source
Saw palmetto alone, standard or high dose	No better than placebo at up to 960 mg a day	CAMUS trial, 369 men
Saw palmetto alone, pooled trials	Little to no benefit, high-certainty evidence	Cochrane 2023
Saw palmetto with other herbs	Uncertain; low-certainty evidence	Cochrane 2023
Prostatitis and pelvic pain	No significant benefit in five studies	NCCIH, 2022 review

Is saw palmetto safe?

NCCIH describes saw palmetto as well tolerated. It has been used in research studies for up to three years. Adverse effects are mild and infrequent, and may include digestive symptoms, dizziness and headache. It may be unsafe during pregnancy or while breastfeeding.

One practical point is worth knowing. NCCIH says saw palmetto does not appear to affect PSA readings, even in higher-than-usual amounts. So a supplement should not hide a blood test result. Even so, the bigger risk with any prostate supplement is delay. Urinary symptoms can come from causes other than BPH, and MedlinePlus lists pain with urination or bloody urine as possible signs of infection. If you have symptoms, a doctor can examine you and run tests. Taking a capsule for months before that visit only postpones the answer.

How do prostate supplement offers use saw palmetto?

Most offers put saw palmetto first on the ingredient list, because it is the best-known name. The sales pages then add other herbs, minerals and extracts. Our reviews show three patterns.

• The page cites a study that undercuts it. Our Prostadine review found that the strongest study the page lists, a 2006 saw palmetto trial in the New England Journal of Medicine, found no significant difference from placebo. The page also gives no amount for any ingredient in its 2 ml dose.
• The dose is printed, and it is low. Our Protoflow review credits the page for printing an exact amount for every ingredient. Saw palmetto sits at 84.5 mg, about a quarter of the 320 mg standard dose. As CAMUS shows, even triple that standard dose did not beat placebo.
• No dose at all. Our Prosta Peak review found no milligram amount for any ingredient and no total blend weight on the page. Our Fluxactive review found 14 ingredients inside one proprietary blend, so no ingredient can be compared with a study.

A hidden dose is a real problem for any ingredient. For saw palmetto, the problem is bigger, because the trials already suggest the herb alone does not change symptoms. A well-made label can only tell you what you are buying. It cannot tell you that the ingredient does anything.

What should you check before buying a prostate supplement?

1. See a doctor about the symptoms first. BPH is common, but infections and other conditions cause similar symptoms.
2. Find the saw palmetto amount. Studies use extract doses such as 320 mg a day. If the page gives no amount, there is nothing to compare.
3. Read the references. If the page cites a saw palmetto study, look up what that study found. Some cited trials found no benefit.
4. Watch for disease-cause claims. A supplement should not promise to treat or reverse an enlarged prostate. That is a drug claim.
5. Compare prices per month. Bundles of six bottles are pushed hard. Our best men's health supplements list shows how the category compares.
6. Know the refund terms. Some require you to mail the bottles back. Our ClickBank refund guide and Digistore24 refund guide explain the steps.

FAQ

Does saw palmetto shrink the prostate?

The sources we read measured urinary symptoms, not prostate size. The Cochrane review found little to no benefit on symptoms, and the CAMUS trial found no advantage over placebo at up to three times the standard dose.

What is the usual saw palmetto dose in studies?

The standard dose in CAMUS was 320 mg of extract a day. The same trial raised it to as much as 960 mg a day (three doses) in its later weeks. Compare label amounts with those numbers, and remember the extract weight is what counts.

Does saw palmetto affect a PSA test?

NCCIH says saw palmetto does not appear to affect PSA levels, even in higher-than-usual amounts. Tell your doctor about any supplement you take before tests.

Is a saw palmetto blend better than saw palmetto alone?

The Cochrane review said the evidence for combinations is more uncertain, rated as low certainty, and it could not draw firm conclusions. A blend that hides its amounts is even harder to judge.

None of this is medical advice. See our men's health reviews for more offers, and talk to a doctor or pharmacist about any supplement, especially if you take other medicines.