Saw palmetto extract does not shrink prostate size (redux)


Saw palmetto extract (made from the berries of the saw palmetto plant, Serenoa repens) is widely used by many men to prevent or treat benign enlargement of the prostate (benign prostatic hyperplasia). While it is not known to have any effect on prostate cancer, the use of saw palmetto has long been a topic of discussion in the prostate cancer community.

Data from a new, large, randomized, double-blind clinical trial comparing increasing doses of saw palmetto extract to a placebo in the treatment of lower urinary tract symptoms in men with enlarged prostates have now (once again) shown that saw palmetto appears to have no discernable benefit over a placebo. This is not the first, recent trial to show such a result, but it is the first randomized, double-blind, placebo-controlled trial to show such a result using daily doses of saw palmetto extract of up to three times the customary “standard” dose of 320 mg/day.

Barry et al. enrolled 369 men into this trial at 11 study sites between June 2008 and October 2010. All patients were aged 45 years or older, had a peak urinary flow rate of ≥ 4 ml/sec, and had an American Urological Association Symptom Index (AUASI) score between 8 and 24. The patients were all given one daily dose of a specific brand of saw palmetto extract (Prosta Urgenin Uno capsules) for weeks 1 through 23, then two daily doses for weeks 24 through 47, and three daily doses for weeks 48 through 71.

Study findings were as follows:

  • In the group of men randomized to receive saw palmetto extract
    • The mean AUASI score at baseline was 14.42.
    • The mean AUASI score at 72 weeks was 12.22.
    • The decrease in the mean AUASSI score was −2.20 points.
  • In the group of men randomized to receive a placebo
    • The mean AUASI score at baseline was 14.69.
    • The mean AUASI score at 72 weeks was 11.70.
    • The decrease in the mean AUASSI score was −2.99 points.
  • There was no observable, favorable effect of saw palmetto extract on any secondary outcomes (including measures of urinary bother, nocturia, peak uroflow, post-void residual volume, PSA level, participants’ global assessments, sexual function, continence, sleep quality, and prostatitis symptoms).
  • There were no adverse effects attributable to saw palmetto extract.

So there is good news and there is bad news. The good news is that using saw palmetto extract seems to have no significant adverse effects. The bad news is that taking the extract in the hope that it affects prostate size or symptoms of prostate enlargement appears to be a waste of time and money.

There is extensive discussion of the results of this study on other sites, including MedPage Today, the Los Angeles Time Booster Shots blog, Medscape, and Reuters.

In an interview mentioned on the MedPage Today web site, Dr. Aaron Katz, of the Center for Holistic Urology at Columbia University in New York City, apparently said that, in his opinion, what this study shows is that “this particular saw palmetto extract is not helpful when given alone.” In his practice, saw palmetto is consistently used in combination with other plant extracts (e.g., those from stinging nettles or the bark of Pygeum africanum). He feels that saw palmetto extract in conjunction with such other extracts can be helpful for some men with mild lower urinary tract symptoms — particularly those “men with BPH who wish to avoid [prescription] medications.”

9 Responses

  1. 50% of the saw palmetto patients at week 48 improved with a 3+ point drop in their AUA scores. I guess I would rather first try a product with no side effects and a 50% chance of improvement before starting on a heavy drug which might cause heavy side effects.

    It seems the placebo response in this study was quite high at 50% so it seems wacky to say saw palmetto didn’t work, even if it did not outperform placebo, when 1/2 the patients showed improvement … I think this just shows the high placebo effect in this study.

  2. But Joe … That’s exactly the point … You could have taken an M&M and it would have worked as well as the saw palmetto! The only effect of the saw palmetto was also “a placebo effect.”

  3. Well … it’s getting to be time for some more book revisions again.

  4. The key phrase is double-blind clinical trial. Saw palmetto can’t pass the test when neither the patients nor the researchers know who is getting a placebo and who is getting the treatment.

  5. I am a 62-year-old male with no loss of urinary output. I do have a large prostate. I noticed a buzzing or thrust feeling in the prostate area normally in the morning in bed and it was aggravated by my position. I started re-taking my Saw Pel. and the next day the buzzing was gone. I will continue to take the Saw Pel. Too much buy out by today’s doctors to the super-rich pharmacological industry.

  6. I agree with Kaptnk. I have been using it and have discerned a difference. My prostate problems usually leave me with high infection and in hospital. Upon the onset of the symptoms, I started the saw palmetto, and got relief. This isn’t a placebo. One must wonder who finances many of these studies. Try it for yourself and be the judge. If it doesn’t work, you’ve lost $30, if it does work it’s all good.

  7. According to a statement on another web site:

    “Surprisingly, the review only covered three studies. While their initial analysis looked at 17 studies including 2,008 patients, and a previous study by some of the same researchers (including Dr. Wilt) examined 21 studies with 3,139 patients, the researchers eliminated all but three studies, which covered only 661 patients.

    “The researchers basically eliminated any study that did not use the American Urological Association’s Symptom Index or the International Prostate Symptom Scores method to evaluate prostate improvement.”

  8. Since this statement on the other web site is written by a self-described “naturopath”, it is not entirely surprising that he might look at this issue rather differently than the reviewers. The problem is that no really well conducted, randomized, double-blind, placebo-controlled trial has ever shown significant clinical effectiveness for saw palmetto in the management of BPH. This doesn’t mean it may not be helpful for some men with BPH under some circumstances, but it does mean that it has a very low probability of helping most men with BPH.

  9. I’m 77 years old; I’ve taken saw palmetto for about 20 years. Early on I thought what the heck, I’m going to discontinue the saw palmetto. Within 2 weeks I noticed a much decreased urinary output.

    So … back on the saw palmetto. My study complete.

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