Supplement analysis backed by scientific evidence · PT

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Limited evidenceMen's health

Saw Palmetto

Saw palmetto is the best-studied prostate supplement and the trials are consistently negative: 32 randomized trials in over 5,600 men show it performs no better than placebo for urinary symptoms, even at double and triple the standard dose.

What the science says

  • Improves lower urinary tract symptoms in BPH Limited evidence

    The Cochrane review pooled 32 randomized trials in 5,666 men and found Serenoa repens no better than placebo for urinary symptom scores (IPSS mean difference approximately 0.16 points, far below the roughly 3-point threshold for clinical relevance), nocturia, or peak urine flow. Crucially, the null result held in trials using double and triple the usual 320 mg/day dose, which removes the "underdosed" explanation.

  • Matches placebo at the standard 320 mg/day dose in a rigorous trial Limited evidence

    A New England Journal of Medicine trial randomized 225 men with moderate-to-severe BPH to 160 mg saw palmetto twice daily or placebo for one year and found no difference in AUA symptom index change (about -0.68 vs -0.72 points), peak urinary flow rate, prostate size, residual volume, PSA or quality of life. This was a well-blinded trial with a validated extract and it found nothing.

  • Reduces androgenetic alopecia (hair loss) Limited evidence

    Interest comes from weak in-vitro 5-alpha-reductase inhibition, but human hair-loss evidence is limited to a handful of small, short, often unblinded trials with subjective photographic endpoints. Effect sizes, where reported, are far below finasteride's, and no adequately powered comparison exists.

Dosage & safety

Studied doseThe standard studied dose is 320 mg/day of lipidosterolic extract, usually 160 mg twice daily, with trials running 6-72 weeks. Cochrane also assessed 640 mg/day and 960 mg/day without finding benefit, so escalating the dose is not a rational response to non-response. Berry powders and non-lipidosterolic preparations have not been meaningfully studied.
SafetySide effect rates in trials were similar to placebo — mild GI upset, headache and occasional decreased libido. Rare case reports link saw palmetto to acute hepatitis and acute pancreatitis. It has weak antiplatelet activity, so stop it about 2 weeks before surgery and use caution with warfarin or antiplatelet drugs. Reports on whether it lowers PSA are mixed, but any PSA suppression could delay prostate cancer detection — tell your urologist you are taking it. Because of its antiandrogenic premise, it should be avoided in pregnancy and by women who may become pregnant. The bigger practical risk is opportunity cost: men with progressive BPH who rely on saw palmetto instead of alpha-blockers or 5-alpha-reductase inhibitors risk retention and upper-tract damage.

Scientific references

Where to buy

NOW Foods, Saw Palmetto Extract, 90 Veggie Softgels

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