Saw palmettoSerenoa repens
The most used herbal for urinary symptoms in men, with a trial record that is genuinely split. Standardized lipid extracts at 320 mg a day helped in several European trials; the largest US trial found nothing over placebo.
- Dose used in trials
- 320 mg/day of a standardized lipidosterolic extract (85 to 95 percent fatty acids), usually as 160 mg twice daily
- Time to effect
- Trials measured at 8 to 12 weeks; anything not felt by 12 weeks is unlikely to appear
What the evidence says
Dozens of trials since the 1990s. Early meta-analyses were positive. The 2011 CAMUS trial (369 men, up to 960 mg a day for 72 weeks) found no difference from placebo on symptom scores. A 2024 Cochrane update concludes little or no effect on symptoms or flow. Hexane-extracted, standardized products fared better than generic powders in the subgroup analyses that exist.
What it is
Saw palmetto is the fruit of a dwarf palm native to the southeastern United States. The active fraction is the fat-soluble part of the berry, which is why the products used in positive trials are lipid extracts, not ground berry powder.
The proposed mechanism is mild inhibition of 5-alpha-reductase, the enzyme finasteride blocks far more strongly, plus some anti-inflammatory activity in prostate tissue.
What the trials actually found
Through the early 2000s the picture looked good: pooled analyses of mostly European trials showed improvements in nighttime urination and flow similar to finasteride, with fewer side effects.
Then two large, well-run American trials landed. STEP (2006) gave 225 men 320 mg a day for a year and found no benefit over placebo. CAMUS (2011) escalated the dose to 960 mg a day over 72 weeks and again found nothing.
Defenders point out that the American trials used a different extract than the European ones, and that subgroup analyses favour hexane-extracted, standardized products such as Permixon. That is a reasonable point, but it also means a generic 'saw palmetto powder' on a supplement label is the version with the weakest support.
Honest summary: it might help some men a little, it is unlikely to shrink the prostate, and any benefit is smaller than tamsulosin or finasteride.
How to tell a good product from a bad one
Look for 320 mg per day of an extract standardized to 85 to 95 percent fatty acids and sterols. Softgels are usually the lipid extract; hard capsules of 'berry powder' usually are not.
If a formula lists saw palmetto inside a proprietary blend without a milligram figure, assume the dose is below what was tested.
Side effects
- Mild stomach upset, usually resolved by taking it with food
- Headache in a small minority
- Rare reports of reduced libido, far less common than with finasteride
Interactions
- May add to the effect of blood thinners (warfarin, clopidogrel); check with your prescriber
- Can lower PSA slightly, so tell your doctor before a PSA test
- No known interaction with tamsulosin or finasteride, but it is pointless alongside finasteride, which works on the same pathway more strongly
NOW Saw Palmetto Extract 320 mg with pumpkin seed oil, 90 softgels
Pick any product that states 'standardized to 85 to 95 percent fatty acids' and 320 mg per day on the label. Powdered berry without that standardization is what the negative trials used.
Check price on AmazonAs an Amazon Associate we earn from qualifying purchases. Buy from the brand or an authorised seller; forum users report counterfeit supplements from third-party sellers.
Products we reviewed that contain it
- Prostadine review →
Liquid prostate drops built around seaweed extracts and saw palmetto. Dose of saw palmetto not disclosed on the label.
Frequently asked questions
- Does saw palmetto shrink the prostate?
- No trial has shown a meaningful reduction in prostate volume. The claimed benefits are on symptoms, not size.
- Is it safe to take long term?
- Trials up to 72 weeks found a safety profile similar to placebo. Long-term data beyond that is observational only.
- Can I take it with tamsulosin?
- No interaction has been reported. Whether it adds anything on top of tamsulosin has not been tested properly.
Other prostate ingredients
This article is for information only and is not medical advice. Statements about supplements have not been evaluated by the FDA. Do not start, stop or combine supplements with prescription medication without talking to your doctor or pharmacist. If you cannot pass urine, or have chest pain, confusion or fainting, seek emergency care.
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