Ripe saw palmetto berries (Serenoa repens), the part the extract is made from

Strong evidence21 studies

How we rate

“Strong” = several concordant meta-analyses or systematic reviews. “Moderate” = one synthesis, or several controlled trials. “Limited” = early trials only. The rating is about the quality of the studies, not about how useful the supplement is.

Saw palmetto (saw palmetto)

Saw palmetto: no better than a placebo for urinary symptoms of the prostate, across 32 trials and 5,666 men, even at triple the dose; well tolerated.

Benefits

Hexane extract: 0.64 fewer nighttime awakenings and 2.75 mL/s greater maximum urinary flow rate than placebo, across 27 studies and 5,800 patients.
One positive trial on the prostate: in 354 Chinese patients, 24 weeks at 320 mg per day improve flow rate, symptoms and quality of life compared to placebo.
Mild symptoms without prostate disease: less discomfort and fewer daytime urinations in 66 Japanese adults, over 12 weeks.
In women: fewer daytime urinations after 12 weeks in adult Japanese women, especially those with the most marked symptoms.
Hair: in 60 adults who found their hair thinner, more hair and a higher density than with placebo after 180 days.
Compared to tamsulosin: similar efficacy on symptoms after 6 months (4 studies, 1,080 patients), with fewer ejaculation disorders and less decreased libido.

Precautions

Side effects: mild, infrequent and reversible, comparable to placebo (abdominal pain, diarrhea, nausea, fatigue, headache, decreased libido). High doses: up to three times the usual dose for 18 months, no more side effects or disturbed blood tests than with placebo. PSA: unchanged compared to placebo, even at high dose. Sexual function: no more negative effects than placebo, across 20 studies. Medications: no effect on the enzymes that eliminate many drugs (cytochromes P450) in 12 volunteers. Limitations: prostate: across 32 trials and 5,666 men, no better than placebo on urinary symptoms, flow rate or prostate size, even at double or triple the dose. In the STEP trial (225 men, one year), no difference from placebo on symptoms, flow rate, prostate size or quality of life. A network meta-analysis of 22 trials and 8,564 patients judges the benefit compared to placebo to be minimal, with no clinical significance. Alone, it makes little or no difference, in the short as in the long term, across 27 trials and 4,853 participants. Hair: 38% regrowth vs 68% with finasteride in two years, in a trial without placebo; the positive trial versus placebo includes only 60 people.

Recommended dosage

320 mg of extract per day (or 160 mg twice daily) in most trials; up to three times this dose tested, without performing any better.

How to take it

For whom: most trials involve men with urinary symptoms related to an enlarged prostate; a few involve women or adults without prostate disease.
Dose: 320 mg per day, in a single dose or in two doses of 160 mg.
Doubling or tripling the dose: did no better than placebo over 72 weeks in the CAMUS trial.
Extract: the most favorable results come from a specific hexane extract (Permixon), studied separately.
Duration: from 12 to 72 weeks in prostate trials, two years in the hair loss trial.
What does not work: on the prostate, the two major double-blind trials, STEP and CAMUS, do no better than placebo.

Did you know?

In a 12-week trial of 100 men, all saw their prostate symptoms improve, including those on placebo: saw palmetto extract did no better.

What the studies say

This systematic review and meta-analysis evaluated the effects of saw palmetto (Serenoa repens) alone or in combination for lower urinary tract symptoms (LUTS) due to benign prostatic hyperplasia. The study, including 27 trials and 4853 participants, showed that saw palmetto alone brings little to no difference on urinary symptoms, quality of life, and adverse events, in both the short and long term. Uncertainty is greater concerning the effects of saw palmetto in combination with other herbal medicines.
Trivisonno LF, Sgarbossa N, Alvez GA, Fieiras C, Escobar Liquitay CM, Jung JH, Franco JVA. — Investigative and clinical urology (2021) — View the source study

For information only: not a substitute for medical advice. Dietary supplements are not a replacement for a varied, balanced diet. Learn more