Doses of saw palmetto extract up to three times the standard did not reduce lower urinary tract symptoms associated with benign prostatic hyperplasia (BPH), a randomized, placebo-controlled trial showed.
Through 72 weeks of treatment, the American Urological Association Symptom Index (AUASI) score dropped by 2.20 points in men taking escalating doses of saw palmetto extract, according to Dr. Kevin McVary of Northwestern Memorial Hospital in Chicago, and colleagues. The change was not statistically different from that achieved with a placebo, the researchers reported in the Sept. 28 issue of the Journal of the American Medical Association.
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The researchers did acknowledge, however, that the findings -- based on the use of a single extract -- might not be generalizable to other products.
"Nevertheless," they added, "a recent series of negative trials using different saw palmetto extract preparations makes it increasingly unlikely a dose of some preparation will be identified that is better than placebo."
Over-the-counter extracts made from the berries of the saw palmetto dwarf palm tree are popular remedies for treating lower urinary tract symptoms from BPH because of "easy and convenient access (no need for a doctor visit or prescription)," according to Dr. Muta Issa, a urologist at Emory University and the Atlanta VA Medical Center.
In addition, he wrote in an email to ABC News and MedPage Today, "there is ... [an] unwarranted psychological fear of loss of sexual ability with prostate medications. As such, men convince themselves that herbs are natural and do not interfere with their sexual ability."
Although a 2002 Cochrane review that included 21 clinical trials found that saw palmetto extracts significantly reduced nocturia, increased self-rated improvement, and improved peak uroflow, an update conducted in 2009 found that only the effect on nocturia remained significant.
Other recent studies have questioned the efficacy of the extract as well. The largest of them, the STEP study, found that a standard dose of 320 mg/day did not have any effect on symptom scores or any secondary endpoints.
"The efficacy of saw palmetto in BPH is very questionable," Issa said.
The current study evaluated whether tripling the dose might prove effective. Researchers at 10 U.S. sites and one Canadian site randomized 369 men ages 45 and older (mean age 61) to receive saw palmetto extract (sold as Prosta Urgenin Uno capsules) or placebo for 72 weeks.
The men took a standard dose of 320 mg/day for 24 weeks, a double dose for the next 24 weeks, and a triple dose for the final 24 weeks.
From baseline to 72 weeks, the mean AUASI scores decreased from 14.42 to 12.22 in the saw palmetto group and from 14.69 to 11.70 in the placebo group. The mean difference in score change was 0.79 points, favoring placebo, although the difference was not significant.
There was also no difference in the percentage of patients who had at least a three-point drop in symptom scores.
Adverse events were almost entirely minor and occurred at similar rates in the two groups overall. There were significantly more instances of physical injury or trauma in the saw palmetto group.
Despite the negative results of the trial, Dr. Aaron Katz, director of the Center for Holistic Urology at Columbia University in New York City, said that he uses saw palmetto extracts in his practice and that he feels that they can help many men with mild lower urinary tract symptoms.
The take-away message from the current study is that this particular saw palmetto extract is not helpful when given alone, he said in an interview, adding that in his practice, saw palmetto is always given with other extracts, including those from stinging nettles or the bark of the Pygeum africanum, an African evergreen.
Katz said that he plans on continuing to use saw palmetto as part of the treatment plan for men with BPH who wish to avoid medications.