Dr. Kumar’s Take:
The source here is a drug review of Serenoa repens in androgenetic alopecia, not a clinical trial of oral and topical saw palmetto oil. It is a short paper by a dermatologist summarising what little published evidence exists, and its verdict is blunt: significant evidence for advocating saw palmetto in androgenetic alopecia is lacking, and larger clinical trials are warranted. The reason I still tell patients about it is the reason the author gives. People are buying it online as a “safer” alternative to finasteride, and because it behaves like a 5 alpha reductase inhibitor it can lower PSA, which can delay a prostate cancer diagnosis in a man who is self medicating and never mentions it to his doctor.
Free guide: I put the complete, evidence-based plan into The Hair Loss Protocol, a downloadable guide you can take to your doctor.
Brief Summary:
Serenoa repens, sold as saw palmetto, is the most popular of the botanically derived 5 alpha reductase inhibitors marketed for benign prostatic hypertrophy and androgenetic alopecia. This review collects the human evidence in hair loss and finds very little of it: one small oral study, one topical study presented as a conference abstract, and one shampoo comparison also presented at a meeting. The author concludes that evidence to support efficacy is thin and that larger clinical trials are needed. The paper also flags a practical safety issue, that saw palmetto can lower PSA the way other 5 alpha reductase inhibitors do.
Key Takeaways:
✔ This is a drug review of the published evidence, not a new trial.
✔ In a small study of 10 men with androgenetic alopecia taking oral saw palmetto, improvement was seen in 60%.
✔ Saw palmetto may reduce PSA levels by 50% after 6 to 12 months, which can mask early prostate cancer in men self medicating.
Study Design:
This is a drug review published in the Journal of Cutaneous and Aesthetic Surgery. Rather than enrolling patients, the author surveys the source, contents, proposed mechanism and reported uses of Serenoa repens, then examines the studies cited in androgenetic alopecia. Those are: a small study of 10 males aged 23 to 64 with androgenetic alopecia taking oral saw palmetto; a study of 34 men and 28 women aged 18 to 48 using a topical saw palmetto extract in a lotion and shampoo base for three months, assessed by sebometry, pH metry, hydration studies and phototrichogram, and presented at the fourth Intercontinental Meeting of Hair Research Societies in June 2004; and a comparison of ketoconazole shampoo with and without added 0.5% saw palmetto extract, presented at the 13th annual meeting of the European Hair Research Society in Genoa.
Results:
✔ In the 10 male participants on oral saw palmetto, improvement was seen in 60%.
✔ The three month topical study reported a 35% increase in hair density and a 67% increase in sebum reduction.
✔ Adding 0.5% saw palmetto extract to ketoconazole shampoo gave better results than ketoconazole alone.
✔ Side effects are described as uncommon, the most common being mild stomach discomfort that can be eased by taking the supplement after food.
How Saw Palmetto Works for Hair Loss
Saw palmetto is an extract from the berries of the palm Serenoa repens, also called Serenoa serrulata or Sabal serrulata. The purified extract contains 85 to 90% fatty acids and sterols, with carotenoids, lipases, tannin, sugars and fatty acids including caprylic acid, palmitic acid, oleic acid and beta sitosterol. The combination of the liposterolic extract and beta sitosterol is the part claimed to improve androgenetic alopecia.
The proposed mechanism is the same as finasteride, blocking 5 alpha reductase. Saw palmetto is also thought to reduce dihydrotestosterone uptake by the hair follicle and to reduce the binding of dihydrotestosterone to androgen receptors. That is the theory the marketing rests on. The clinical evidence behind it, as this review lays out, is a handful of small studies, two of which exist only as conference abstracts.
Related Studies and Research
Saw palmetto is one of several treatments studied for hair loss. To explore other approaches, consider:
- Androgenetic Alopecia Treatments: A Comprehensive Review: Where saw palmetto fits among pharmaceutical and non-pharmaceutical interventions.
- Low-Level Light Therapy: A Drug-Free Approach to Hair Regrowth: Understanding how light therapy compares to botanical DHT inhibitors.
- Microneedling and Hair Growth: Can Skin Stimulation Improve Results?: Investigating whether microneedling enhances the absorption of natural hair growth products.
- Minoxidil, Finasteride, and Dutasteride: A Scientific Comparison: Examining how pharmaceutical DHT blockers compare to natural alternatives like saw palmetto.
Frequently Asked Questions
How long does it take to see results with saw palmetto for hair growth?
The topical study described here ran for three months before hair density was measured, so this is a treatment to judge over months rather than weeks.
What dose is typically used?
The review gives a recommended dose of 160 mg twice a day. Two forms are sold, dried saw palmetto berries and saw palmetto extract in tablet form.
Are there any side effects of using saw palmetto?
Side effects are said to be uncommon, and the most common one is mild stomach discomfort, which can be eased by taking the supplement after food. The more important issue is that saw palmetto, like other 5 alpha reductase inhibitors, may reduce PSA levels by 50% after 6 to 12 months of treatment. If you are taking it and your doctor does not know, an early prostate cancer can be missed.
Can women use saw palmetto for hair loss?
The topical study included 28 women aged 18 to 48 alongside 34 men. I would still have any woman considering it speak to her doctor first, particularly if pregnant or breastfeeding.
How does saw palmetto compare to prescription medications?
It is promoted by some as a safer alternative to finasteride, but this review points out that proper clinical trials to support its efficacy are lacking, and that the products remain popular regardless. Saw palmetto is listed in the US Pharmacopoeia, yet it falls under the guidelines for food supplements and is not regulated as a drug by the FDA, so what is in the bottle is not held to the standard a prescription tablet is.
Conclusion:
My reading of this review is that saw palmetto is a plausible idea with thin evidence behind it. The mechanism is reasonable, the extract is cheap and easy to buy, and the published human data in androgenetic alopecia amounts to one small oral study and two conference abstracts. The author’s conclusion is that significant evidence for advocating the drug in androgenetic alopecia is lacking, but that physicians should know about it because patients are already using it and will ask. If you are taking it, tell your doctor, so a falling PSA is read correctly.
