NEW YORK - When Dr. Stephen Bent and his research colleagues put a popular herbal pill to the test, they wanted to find out if it really did help men suffering from the discomforts of an enlarged prostate.
But in contrast to previous studies, their research showed the plant extract, saw palmetto, was no more effective than dummy capsules in easing symptoms for the 225 volunteers in the yearlong study.
"It would have been nice if we could have said, 'Here's a great alternative for everybody. Keep going,'" said Bent, of the San Francisco VA Medical Center. "Now we're left with more questions."
More than 2 million American men take the herb to treat an enlarged prostate and it is widely used in Europe, the researchers said. They said earlier tests that showed improvement were smaller and shorter than their federally funded study.
The prostate is a walnut-sized gland that surrounds the urethra, the tube that carries urine from the bladder. Benign enlargement is a common condition as men age, and it causes problems with urination. The condition has nothing to do with prostate cancer.
The saw palmetto is a small palm native to the southeastern United States. The extract comes from its olive-size berries and is sold over-the-counter in capsule form. As a dietary supplement, it does not need government approval.
"If someone's taking it and they feel like they're getting a benefit, then they probably ought to keep taking it - at least until there's more research to confirm these results," Bent said.
The findings are published in Thursday's New England Journal of Medicine. Some of the researchers have received fees or support from drug makers.
The study recruited men over 49 with enlarged prostates who had moderate to severe symptoms. They took 160 milligrams of saw palmetto twice a day or similar-looking dummy capsules. At each visit, they filled out a symptoms survey and their urine flow was measured.
After a year, there was no significant difference between the groups in symptom changes or other measures, the researchers reported.
Bent said the dummy capsule was carefully designed to match the brown color, bitter taste and strong odor of the extract. At the end of the study, 40 percent in the saw palmetto group and 46 percent in the comparison group thought they were getting the extract, showing it was well disguised.
Bent suggested that men in previous studies may have figured out they were getting a placebo.
Mark Blumenthal, head of the American Botanical Council, which follows research on herbs, said saw palmetto is recommended for milder symptoms than those included in the latest study.
"I don't have a fault for them raising the bar. I do think it's unfortunate they didn't raise the dosage," Blumenthal said.
Bent said they recruited the same kind of patients used to test prescription drugs for enlarged prostate, and the dosage was identical to that used in earlier tests.
A larger study of herbal remedies, including saw palmetto, is in the final planning stages.
In a journal editorial, Drs. Robert S. DiPaola and Ronald A. Morton at the University of Medicine and Dentistry of New Jersey note that only one formula of saw palmetto was tested and suggest that other preparations or doses might work.
"What I tell men is that they may not do themselves any harm by taking it. It's just that I'm not certain they're going to do themselves any good taking it," Morton said.
On the Net:
New England Journal: http://nejm.org
National Center for Complementary and Alternative Medicine: http://nccam.nih.gov/
American Botanical Council: http://herbalgram.org