Ingredient research
Saw Palmetto and the Prostate: What the Evidence Really Shows
Saw palmetto is one of the most studied herbs for urinary symptoms of an enlarged prostate, and the results are disappointing. A 2023 Cochrane review of 27 studies and 4,656 men found little to no benefit at the usual 320 mg a day. Vapofil lists 20 mg, one sixteenth of that dose.
Written by the Vapofil editorial teamUpdated · 8 min read
Background
What is saw palmetto, and why is it in men's supplements?
Saw palmetto is an extract of the berries of a small palm. For decades it has been sold for urinary symptoms of an enlarged prostate, a common condition doctors call BPH.
Because the herb was tied to the prostate for so long, it shows up in many men's formulas. Vapofil lists it first: Saw Palmetto Berry Extract, 20 mg per 2-capsule serving.
The sales page links saw palmetto to claims we do not repeat; each is checked on the sales claims page. Here we look only at what researchers found.
The research
What did the big saw palmetto studies find?
Large, careful trials and a major review all point the same way.
| Source | What was studied | What it found |
|---|---|---|
| Cochrane review, 2023 | 27 studies, 4,656 men; usual dose 320 mg a day | Symptom scores moved 0.90 points versus placebo at 3 to 6 months: "little to no difference" (Cochrane review, Saw palmetto) |
| Two NIH-funded trials | One tested up to three times the usual dose | Saw palmetto "did not improve BPH symptoms" (NCCIH, Saw palmetto) |
| One-year trial (2006) | 225 men, saw palmetto vs placebo | No difference in symptoms, urine flow, prostate size or quality of life (LiverTox, Saw palmetto) |
| MSK summary | Trials and reviews | Some trials showed benefit, but "conflicting data suggest no such effects" (MSKCC, Saw palmetto) |
The Cochrane authors' bottom line was plain: saw palmetto alone "provides little to no benefits for men with lower urinary tract symptoms" (Cochrane review, Saw palmetto). NCCIH sums it up as "probably not helpful" (NCCIH, Saw palmetto).
Reading evidence
Why doesn't more research mean saw palmetto works?
Higher on the ladder means more and better research, not a better result.
- 4Guidelines and large trials
- 3Several trials, pooled
- 2Small human trials
- 1Lab and animal studies
- Vapofil itselfNo trials found(NCCIH, Sexual enhancement supplements)
- Horny goat weed (icariin)Mostly lab and animal(MSKCC, Epimedium) (LiverTox, Horny goat weed)
- Tongkat ali, 100-600 mg extractSmall trials, mixed(Leisegang 2022, Tongkat ali meta-analysis) (LiverTox, Tongkat ali)
- Saw palmetto, 320 mgMany trials: little to no benefit(Cochrane review, Saw palmetto)
- PDE5 inhibitors (prescription)Guideline treatment for ED(AUA, ED guideline) (NIDDK, ED treatment)
Higher means more and better research, not a better result: saw palmetto has strong research showing little benefit for urinary symptoms. Vapofil's doses sit well below the studied amounts, and no trial tested the product.
Saw palmetto sits high because it has been tested so often. That strong research is what shows the small effect. Horny goat weed sits low for the opposite reason: there is too little human data to judge it (MSKCC, Epimedium).
Dose check
How does Vapofil's 20 mg compare with the trial dose?
Each bar is a studied or typical amount. The fill is what two capsules give you.
The studied schedule was 320 mg daily, taken whole or split into two 160 mg doses (LiverTox, Saw palmetto). Vapofil's 20 mg is one sixteenth of that, about 6%. Even the full trial dose showed little to no benefit. A smaller amount has no research behind it. Every label dose is compared with research in the Vapofil dose guide.
In five numbers
What are the key saw palmetto numbers?
Safety
Is saw palmetto safe for most men?
For most healthy men, yes, at studied doses. NCCIH says it is generally well tolerated in studies lasting up to 3 years (NCCIH, Saw palmetto). In the Cochrane review, side effects were about as common as on placebo (Cochrane review, Saw palmetto).
- Uncommon, mild effects: stomach upset, dizziness, headache, nausea, constipation or diarrhea (NCCIH, Saw palmetto) (LiverTox, Saw palmetto).
- MSK also lists tiredness, a stuffy nose and lower libido, mostly at placebo-like rates (MSKCC, Saw palmetto).
- LiverTox rates it a possible, rare cause of liver injury (LiverTox, Saw palmetto).
MSK says saw palmetto may raise the risk of bruising and bleeding with warfarin and other blood thinners (MSKCC, Saw palmetto). It may also add to drugs such as clopidogrel. Ask your doctor first if you take one.
Next steps
What should men with urinary or erection symptoms do instead?
See a doctor. Urinary symptoms have more than one possible cause, and a proper exam sorts them out. Bring the label of any supplement you take.
The same goes for erection problems. ED can be an early sign of heart disease or diabetes, and the American Urological Association tells doctors to check for both (AUA, ED guideline). Our ED guide explains what to expect.
The amount is printed, which let us check it. It is a small share of a dose that already showed little benefit. Read the whole saw palmetto profile or the full label.
FAQ
Saw palmetto FAQ
Does saw palmetto actually work for an enlarged prostate?
Probably not. A 2023 Cochrane review of 27 studies and 4,656 men found saw palmetto alone gave little to no benefit for urinary symptoms at the usual 320 mg a day. Two NIH-funded trials, one at up to three times that dose, found no improvement. NCCIH calls it probably not helpful.
How much saw palmetto is used in studies?
Trials used 160 mg twice a day or 320 mg once a day, according to LiverTox, and the Cochrane review names 320 mg as the usual daily dose. One NIH-funded trial went up to three times the usual dose and still found no improvement in symptoms. No dose has clear proof of benefit.
Can a 20 mg dose of saw palmetto help urinary symptoms?
There is no research showing it is. Vapofil lists 20 mg of saw palmetto berry extract per day, one sixteenth of the 320 mg used in trials. Since even the trial dose showed little to no benefit for urinary symptoms, a much smaller amount has no evidence behind it.
What are the side effects of saw palmetto?
They are uncommon and usually mild. NCCIH and LiverTox list stomach upset, dizziness, headache, nausea, constipation and diarrhea. MSK adds tiredness, a stuffy nose and lower libido. In the Cochrane review, side effects were about as common as on placebo. LiverTox rates it a possible, rare cause of liver injury.
Can I take saw palmetto with blood thinners?
Ask your doctor first. MSK says saw palmetto may increase the risk of bruising and bleeding when taken with warfarin and other blood thinners, and may add to the effect of antiplatelet drugs such as clopidogrel. Bring the supplement label to your appointment so the exact amount can be checked.
Can saw palmetto affect sex drive?
It can in a few men. MSK lists decreased libido among saw palmetto's reported side effects, along with stomach upset and headache, and says these were mostly mild and similar to placebo. If your sex drive changes after starting any supplement, stop it and mention the change to your doctor.
Who wrote this
Written and reviewed by
Plain-language pages built from the label, the sales page and linked public health sources.
Last updated . Our editorial standards explain how we check reviews. This website is run by Vapofildaily, a U.S. stocking partner for Vapofil, not by the manufacturer or the distributor named on the label. Purchases through our order links earn us a commission.
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Every word on the Vapofil label, typed out, with the three lines that are easy to misread.
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