Saw palmetto (Serenoa repens) is a small, slow-growing palm native to the southeastern United States, particularly Florida. Its berries — dark, olive-sized fruits — have been used by Native American communities as food and medicine for centuries. Today, saw palmetto berry extract is one of the best-selling herbal supplements in North America and Europe, studied primarily in the context of benign prostatic hyperplasia (BPH) and hair thinning in men.
Mechanism: 5-alpha reductase inhibition
The primary proposed mechanism of saw palmetto involves inhibition of 5-alpha reductase (5-AR), the enzyme responsible for converting testosterone to dihydrotestosterone (DHT). DHT is a more potent androgen than testosterone and plays a key role in prostate growth and in androgenetic alopecia (male pattern baldness). By inhibiting 5-AR, saw palmetto theoretically reduces DHT levels in prostate tissue and hair follicles without substantially altering circulating testosterone levels.
Saw palmetto inhibits both isoforms of 5-AR (type I and type II), while the pharmaceutical drug finasteride selectively inhibits only type II. Some researchers argue this dual inhibition may give saw palmetto a broader mechanism, though its inhibitory potency is lower than that of pharmaceutical drugs.
Saw palmetto for BPH
Benign prostatic hyperplasia — the non-cancerous enlargement of the prostate gland — affects the majority of men over 60 and causes urinary symptoms including frequent urination, weak stream, and difficulty starting urination. Saw palmetto has been studied in multiple randomised controlled trials for BPH symptom relief. A 2009 Cochrane review of 30 studies found that saw palmetto produced modest improvements in urinary symptom scores and flow rates, though a subsequent large US trial (STEP trial, n=225) found no significant difference between saw palmetto and placebo over 72 weeks.
European phytomedicine guidelines, particularly in Germany and France, have been more favourable toward saw palmetto for mild-to-moderate BPH than US guidelines, reflecting different standards for evidence evaluation.
Saw palmetto for hair thinning
Given the shared DHT mechanism with androgenetic alopecia, saw palmetto has been investigated for hair loss. A randomised 24-week study published in the Journal of Alternative and Complementary Medicine found that 320 mg/day of saw palmetto extract increased hair count by 11.9% compared to placebo. While the evidence is not as robust as for pharmaceutical DHT blockers, it represents a meaningful option for those seeking botanical alternatives.
Form and standardisation
Saw palmetto supplements are most commonly lipophilic (fat-soluble) extracts standardised to 85–95% fatty acids and sterols — the active fraction. Whole berry powder preparations contain much lower concentrations of the active components and have less clinical evidence than standardised extracts.
Saw palmetto in Lebanon
Supplements & More carries standardised saw palmetto extract capsules from US brands, available with cash on delivery across Lebanon.