Saw Palmetto
Saw palmetto extract is the most widely used herbal remedy for enlarged prostate symptoms, and it does inhibit 5-alpha reductase, the enzyme that converts testosterone to DHT. Two large NIH-funded trials in the US found that it relieved urinary symptoms no better than placebo, even at three times the usual dose.
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What It Does
The liposterolic extract of saw palmetto berries is mostly free fatty acids, with lauric, oleic, and myristic acids prominent, plus phytosterols. In laboratory studies it inhibits both types of 5-alpha reductase, more weakly than finasteride, and shows anti-inflammatory and alpha-adrenergic effects. In men with BPH, six months of a saw palmetto blend reduced prostate tissue DHT by 32% on biopsy (Marks 2000). That product also contained nettle root, so not all of the effect is attributable to saw palmetto. The Testosterone Metabolism Model uses that tissue-level estimate.
The urinary symptom trials are negative. In the STEP trial, 225 men with moderate to severe symptoms took 160 mg of a CO2 extract twice daily or placebo for a year; symptom scores, urinary flow, prostate size, and PSA did not differ (Bent 2006). The CAMUS trial gave 369 men an ethanol extract at doses escalating from 320 to 960 mg a day over 72 weeks; saw palmetto was no better than placebo at any dose (Barry 2011). A 2012 Cochrane review of 32 trials and 5,666 men concluded that saw palmetto does not improve urinary symptoms or flow, even at double or triple doses (Tacklind 2012). Some European urology guidance treats the hexane extract Permixon separately on the strength of manufacturer-supported trials; it has not been tested in a large independent trial.
For hair loss, an open-label two-year study found that 38% of men improved with saw palmetto and 68% with finasteride (Rossi 2012). It was not blinded and had no placebo group.
Forms and Bioavailability
Absorption ratings are broad tiers. Head-to-head human trials rarely support a finer ranking among well-absorbed forms.
| Form | Absorption | Typical dose | Cost | Labels |
|---|---|---|---|---|
| Liposterolic Extract (85-95% Fatty Acids and Sterols)Permixon, hexane extract | VariableLipid extract of the berry made with hexane, ethanol, or supercritical CO2. The fatty acid fraction carries the 5-alpha reductase activity, and composition differs by solvent and manufacturer. | 320 mg daily | Low | 491 |
| Whole Berry Powderdried saw palmetto berry | LowDried, ground berry with a small fraction of the fatty acid content per gram. | 1-2 g daily | Low |
Labels column: number of labels named as saw palmetto products that list this form. A product can list more than one form, and some labels do not state a form at all.
The extract's composition depends on the solvent: hexane, ethanol, and supercritical CO2 each pull a different mix of fatty acids and sterols. STEP used a CO2 extract and CAMUS an ethanol extract. Whole berry powder carries only a fraction of the lipid content per gram and was not used in the trials.
Typical Dosing
Trials used 320 mg daily of liposterolic extract, as 160 mg twice daily or 320 mg once. The CAMUS trial escalated to 960 mg daily without benefit over placebo.
What to Look For
New urinary symptoms in a man over 50 deserve an exam and a PSA test before any supplement. Saw palmetto does not lower PSA meaningfully, so it will not hide a rising value, unlike finasteride, which roughly halves it.
If you decide to try it anyway, 320 mg a day of a liposterolic extract with its fatty acid content stated is the trial dose. Give it eight to twelve weeks and stop if nothing changes. It is generally well tolerated; mild stomach upset and headache are the most common complaints. Avoid it in pregnancy because of its antiandrogenic activity.
Red flags: "prostate formulas" with 50-100 mg of saw palmetto among a dozen other ingredients, hair regrowth claims, and whole berry capsules. Green flags: extract type named, fatty acid percentage stated, and 320 mg per daily serving.
Liposterolic Extract (85-95% Fatty Acids and Sterols)
The only form worth considering, and the form that failed in the two largest independent trials.
What to look for: Liposterolic extract, 85-95% fatty acids and sterols, 320 mg daily.
Find on iHerb Affiliate linkWhole Berry Powder
Unconcentrated, untested, and not equivalent to the extract.
What to look for: Skip it; the lipid dose per capsule is unknown.
Find on iHerb Affiliate linkProducts on Titrate
2,112 of the 214,745 labels in the NIH Dietary Supplement Label Database list saw palmetto as an active ingredient (1,015 on market). 641 are sold as saw palmetto products by name.
Top on-market labels, ranked by label completeness and simplicity:
Saw Palmetto does not have its own search category yet. Each product above links to its full label in the NIH database.
Related Tools
References
National Center for Complementary and Integrative Health. Saw Palmetto.
Marks LS, Partin AW, Epstein JI, et al. Effects of a saw palmetto herbal blend in men with symptomatic benign prostatic hyperplasia. J Urol. 2000;163(5):1451-1456.
Bent S, Kane C, Shinohara K, et al. Saw palmetto for benign prostatic hyperplasia. N Engl J Med. 2006;354(6):557-566.
Barry MJ, Meleth S, Lee JY, et al. Effect of increasing doses of saw palmetto extract on lower urinary tract symptoms: a randomized trial. JAMA. 2011;306(12):1344-1351.
Tacklind J, MacDonald R, Rutks I, Stanke JU, Wilt TJ. Serenoa repens for benign prostatic hyperplasia. Cochrane Database Syst Rev. 2012;12(12):CD001423.
Rossi A, Mari E, Scarno M, et al. Comparative effectiveness of finasteride vs Serenoa repens in male androgenetic alopecia: a two-year study. Int J Immunopathol Pharmacol. 2012;25(4):1167-1173.
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