Saw Palmetto
Serenoa repens
TL;DR
Saw palmetto at 320 mg/day of liposterolic extract is the most-used botanical for BPH urinary symptoms, but the highest-quality trials — including the large STEP and CAMUS studies — found it no better than placebo. Lower-quality trials are positive, and it remains very well tolerated.
Ideal For
- Men with mild BPH symptoms who have been clinically assessed and want a low-risk trial
- Those who cannot tolerate finasteride's sexual side effects
- Men seeking a well-tolerated adjunct to alpha-blocker therapy
Avoid If
- You have not had urinary symptoms medically evaluated
- You expect an effect equivalent to finasteride or tamsulosin
- You are due for PSA screening without telling your doctor
- You take anticoagulants — mild antiplatelet activity
- You are pregnant or a woman of childbearing potential, due to antiandrogenic effects
- You have surgery scheduled within two weeks
Frequently Asked Questions
Overview
Serenoa repens extract is one of the few supplements whose evidence has moved in the wrong direction as trial quality improved, and that story is more useful than any single result. Early European trials of the liposterolic extract at 320 mg/day reported meaningful reductions in International Prostate Symptom Score, comparable in some cases to finasteride but with far less sexual dysfunction. Cochrane reviews initially reflected that optimism.
Then two rigorous NIH-funded American trials arrived. STEP randomised 225 men to 320 mg/day for a year and found no difference from placebo on symptom score, urinary flow or prostate size. CAMUS escalated the dose to 960 mg/day and still found nothing. The Cochrane review was revised accordingly, and the current honest conclusion is that saw palmetto probably does not improve urinary symptoms more than placebo — while acknowledging that placebo responses in BPH are unusually large, that extract quality varies enormously between products, and that the negative trials used a different extract preparation from many positive European ones.
Mechanistically it is plausible: the fatty acids and phytosterols weakly inhibit both isoforms of 5-alpha-reductase, block androgen receptor binding, and have anti-inflammatory activity in prostatic tissue. The problem is that its 5-alpha-reductase inhibition is far weaker than finasteride and does not reliably lower serum DHT. It is safe, cheap and rarely causes side effects, so a three-month trial is reasonable — but it should never delay proper evaluation of urinary symptoms, and it can lower PSA readings, which matters for cancer screening.
How It Works
- Weakly inhibits both type 1 and type 2 5-alpha-reductase, reducing DHT formation
- Competitively blocks androgen receptor binding in prostatic tissue
- Inhibits cyclooxygenase and lipoxygenase, reducing prostatic inflammation
- Induces apoptosis in prostate epithelial cells in preclinical models
- Blocks alpha-1 adrenergic receptors weakly, relaxing bladder neck smooth muscle
- Reduces prolactin-induced prostatic growth signalling
Quick Facts
- Supports prostate health
- Reduces DHT formation
- Improves urinary flow
- Anti-inflammatory for prostate
- Well-studied for BPH
Benefits & Outcomes
Hair Loss Prevention
Saw palmetto provides natural 5-alpha-reductase inhibition with modest evidence for slowing pattern loss — weaker than finasteride but far better tolerated.
Prostate Health
The best-designed trials found saw palmetto no better than placebo, even at triple the standard dose.
DHT Balance
Weaker than finasteride but meaningfully better than placebo and very well tolerated.
5-Alpha Reductase Inhibition
Saw palmetto may modestly ease urinary symptoms, but controlled trials show little consistent reduction in serum DHT.
Prostate Size Reduction
Saw palmetto does not shrink the prostate in controlled trials.
DHT Reduction
Saw palmetto has little measurable effect on circulating DHT at standard doses.
Hair Follicle Stimulation
Plausible for patterned loss, but far weaker than established treatments.
Health Concerns Addressed
Prostate Cancer
Popular, extensively tested, and consistently negative.
BPH (Benign Prostatic Hyperplasia)
Saw palmetto performed well in early trials but failed in the largest, best-controlled studies.
Facial Hair Growth
Mechanistic rationale only; hirsutism needs hormonal diagnosis and treatment, not extrapolated prostate data.
Frequent Urination
Not recommended for urinary frequency from prostate enlargement. Alpha-blockers and 5-alpha-reductase inhibitors have real effects; this does not.
Supporting Research13 studies
Saw palmetto for the treatment of men with lower urinary tract symptoms
Barry MJ, Meleth S, Lee JY +16 more
In the CAMUS trial, 369 men with moderate lower urinary tract symptoms received saw palmetto extract escalated from 320 to 960 mg/day or placebo for 72 weeks. AUASI symptom scores improved similarly in both arms (-2.20 vs -2.99 points), with no benefit on flow rate, post-void residual or quality of life at any dose.
Efficacy and safety of a combination of sabal and urtica extract in lower urinary tract symptoms: a randomized, double-blind study versus tamsulosin
Engelmann U, Walther C, Bondarenko B
A saw palmetto plus nettle root combination was non-inferior to tamsulosin for IPSS improvement over 60 weeks, with fewer adverse effects.
Effect of Increasing Doses of Saw Palmetto Extract on Lower Urinary Tract Symptoms: A Randomized Trial (CAMUS)
Barry MJ, Meleth S, Lee JY +16 more
Saw palmetto extract escalated up to 320 mg three times daily did not reduce lower urinary tract symptoms more than placebo over 72 weeks.
Natural Hair Supplement: Friend or Foe? Saw Palmetto, a Systematic Review in Alopecia
Evron E, Juhasz M, Babadjouni A +1 more
Natural Hair Supplement: Friend or Foe? Saw Palmetto, a Systematic Review in Alopecia
Treatment of male androgenetic alopecia with topical products containing Serenoa repens extract
Wessagowit V, Tangjaturonrusamee C, Kootiratrakarn T
The average hair count and terminal hair count increased at weeks 12 and 24 compared to baseline
Comparitive effectiveness of finasteride vs Serenoa repens in male androgenetic alopecia: a two-year study
Rossi A
38% of patients treated with Serenoa repens had an increase in hair growth, while 68% of those treated with finasteride noted an improvement.
Evaluation of the Safety and Effectiveness of Nutritional Supplements for Treating Hair Loss: A Systematic Review
There is a potential role for nutritional supplements in the treatment of hair loss.
Saw palmetto for benign prostatic hyperplasia
Bent S, Kane C, Shinohara K +4 more
Saw palmetto 160 mg twice daily produced no improvement in urinary symptom scores, peak flow, prostate size or quality of life versus placebo over one year.
A randomized, double-blind, placebo-controlled trial to determine the effectiveness of botanically derived inhibitors of 5-alpha-reductase in the treatment of androgenetic alopecia
Botanically derived 5AR inhibitors were tested in a placebo-controlled, double-blind study in androgenetic alopecia.
Effects of dietary supplements on androgenetic alopecia: a systematic review and network meta-analysis
Dietary supplements may serve as beneficial adjuncts or alternatives to conventional treatments.
Serenoa repens for benign prostatic hyperplasia
Tacklind J, MacDonald R, Rutks I +2 more
Serenoa repens for benign prostatic hyperplasia: no improvement over placebo in urinary symptom scores.
Efficacy and safety of a hexanic extract of Serenoa repens (Permixon) for the treatment of lower urinary tract symptoms associated with benign prostatic hyperplasia: systematic review and meta-analysis
Vela-Navarrete R, Alcaraz A, Rodriguez-Antolin A +14 more
The hexanic Serenoa repens extract reduced nocturia and improved peak urinary flow versus placebo.
Efficacy and Safety of Hexanic Lipidosterolic Extract of Serenoa repens (Permixon) in Benign Prostatic Hyperplasia: A Systematic Review and Meta-analysis
Novara G, Giannarini G, Alcaraz A +4 more
Hexanic extract reduced IPSS and nocturia versus placebo with a low rate of sexual adverse events.
Safety Information
Potential Side Effects
Well tolerated. May cause mild digestive upset, headache, or dizziness. Effects on PSA testing inconclusive. Typical dose 320mg standardized extract (85-95% fatty acids and sterols) daily.
Contraindications
Pregnancy, lactation and women of childbearing potential due to antiandrogenic effects. Caution with anticoagulants, before surgery, and in anyone undergoing prostate cancer screening.
Drug Interactions
- Anticoagulants and antiplatelet drugs — mild additive bleeding risk
- Finasteride and dutasteride — overlapping mechanism, no added benefit demonstrated
- Hormonal therapies and oral contraceptives — theoretical antiandrogenic interference
- PSA testing — may lower measured values
Pregnancy & Breastfeeding
Pregnancy: likely_unsafe
Breastfeeding: likely_unsafe
Dosage Guidelines
Dosage Used in Studies
320-320 mg
Best Time to Take
Once daily with the largest meal, or 160 mg twice daily
Best Form
Standardised liposterolic or CO2 extract at 320 mg/day, taken with food
Bioavailability
The fatty acid and sterol fraction is lipophilic with absorption significantly improved by a fat-containing meal; plasma levels peak around 1.5 hours after dosing.
Forms Compared
Liposterolic extract (Permixon)
CO2 supercritical extract
Dried berry powder
Combination with nettle root and pygeum
Food & Timing
With food — the active constituents are lipophilic and absorption improves substantially
Medical Disclaimer
The information provided on this website is for educational and informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or before starting any supplement regimen.
Individual results may vary. The statements on this website have not been evaluated by the Food and Drug Administration. Products and information are not intended to diagnose, treat, cure, or prevent any disease.