WEDNESDAY, Feb. 8, 2006 (HealthDay News) -- Millions of older American men use the herbal supplement saw palmetto to treat an enlarged prostate, but a new study concludes the product doesn't work.
A few smaller studies had suggested the extract might be of limited benefit to men with enlarged prostate, clinically known as benign prostatic hyperplasia (BPH).
However, this controlled, blinded study of 225 men found that, "over a 12-month period, saw palmetto was no better than placebo in changing symptoms for this condition," said lead researcher Dr. Stephen Bent, an assistant professor of medicine at the University of California, San Francisco.
His team's research, published in the Feb. 9 issue of the New England Journal of Medicine, is "the most thorough and well-controlled study of the effect of saw palmetto on men with BPH that's ever been done," added Dr. Ronald A. Morton, director of urologic oncology at the Cancer Institute of New Jersey.
Morton, who co-authored a related editorial on the findings, said, "Obviously, for anyone who holds saw palmetto in high regard, these results are a little bit disappointing."
Still, both experts agreed there's no evidence that the herb -- an extract of a seed from a scrub palm that grows naturally in the southeastern United States -- poses any long-term safety hazard to users.
"So, if people are taking this and feel like they are getting some benefit, I think it's worth continuing," Bent said.
He noted that the science on the efficacy of saw palmetto for BPH has been ambiguous, with some studies suggesting a benefit and others finding it to be of no help at all.
"Those studies were of short duration, however, or they didn't use what is now the standard measure of symptoms," Bent said. "They also didn't report on what we call the 'adequacy of blinding' -- we never knew in these prior studies whether patients in the placebo group knew they were on placebo or not."
His team sought to redress a lot of those issues, taking special care to ensure proper blinding and using a pool of patients large enough to gain sufficient statistical power.
They also went to great lengths to choose a top-notch product -- in this case, a brand of saw palmetto capsules marketed in the United States by Rexall-Sundown Co. "We had an external advisory committee from the National Center for Complementary and Alternative Medicine, experts in the field, who evaluated a number of different extracts," Bent said. "They felt this was the best one."
Rexall-Sundown did not respond to requests for comment.
In the trial, the researchers tracked the symptoms of 225 men over the age of 49 with moderate-to-severe BPH. Half of the men took 160 milligrams of saw palmetto twice daily, while the other half took an inactive placebo.
At the one-year mark, the researchers found no difference between the two groups in terms of symptom scores, urine flow rates, prostate size, quality of life, or blood levels of prostate-specific antigen (PSA), a marker for enlarged prostate.
Morton agreed with Bent that saw palmetto is probably safe for users. But he questioned whether too many men plagued by enlarged prostate are using this ineffective remedy in lieu of conventional drugs whose efficacy has long been supported by clinical research.
"There are two medications that we commonly use for men with BPH," said Morton, who is also chief of the division of urology at Robert Wood Johnson Medical School at the University of Medicine and Dentistry of New Jersey. "One includes drugs called alpha blockers, and the other group is 5-alpha-reductase inhibitors. Alpha blockers cause a relaxation of the prostate that makes it easier for a man to urinate. And 5-alpha-reductase inhibitors shrink the prostate."
Either of these medications might be more effective than over-the-counter saw palmetto, Morton said.
He held out the possibility that formulations other than the Rexall-Sundown brand used in the study might still be of benefit to some users. "I do believe, though, that the investigators went to great lengths to ensure the purity of the compound that they were testing," he said.
In a statement, Andrew Shao, vice president of the Council for Responsible Nutrition, a supplements industry trade group, called the findings "puzzling, given that more than 20 studies have shown promising findings for saw palmetto in alleviating symptoms commonly associated with prostate problems."
He agreed the study was "well-designed," but blamed its negative findings on the researchers' focus on patients with moderate-to-severe BPH. According to Shao, the bulk of the positive literature on saw palmetto involves men with milder symptoms.
"The exclusion of those patients with mild symptoms from the study may have reduced [its] ability to detect the benefits we've seen in other trials," he said.
A much bigger issue, according to Bent and Morton, is the lack of regulation and oversight of herbals and other alternative medicines, which are not tested or checked for quality by the U.S. Food and Drug Administration in the same way that conventional drugs are.
"There are millions and millions of men out there who take saw palmetto," Morton said. "And if you review the literature on saw palmetto, it's really all over the map. Quite frankly, I'm not certain that the FDA would approve it -- I'm pretty certain they would not. But it's simply not held to the same standard."
More information
For more on benign prostatic hyperplasia, head to the U.S. National Institute of Diabetes and Digestive and Kidney Diseases.
