NEW YORK -- A popular herbal pill used by millions of men doesn't reduce the frequent urge to go to the bathroom or other annoying symptoms of an enlarged prostate, a rigorous new study concludes.
The yearlong research found the plant extract, saw palmetto, was no more effective than dummy capsules in easing symptoms for the 225 men in the study. The results contrast with previous research that showed it helped.
''This certainly sheds some doubt on whether the product's effective and suggests that it might not work," said the lead researcher, Dr. Stephen Bent, of the San Francisco VA Medical Center.
More than 2 million American men take the herb to treat an enlarged prostate, and it is widely used in Europe, the researchers said. Until their results are confirmed by more studies, men who take saw palmetto and feel it works should probably keep using it, Bent said.
The findings are published in today's New England Journal of Medicine.
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. This 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.
It is the third-highest-selling herbal dietary supplement in the United States, after garlic and echinacea, according to the American Botanical Council. Unlike prescription drugs, dietary supplements do not need government approval.
Bent said he and his colleagues chose saw palmetto to study because of its widespread use and positive findings from previous studies, which were smaller and shorter than his federally funded research. Some of his colleagues have received fees or support from drug makers.
The new 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.
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 research.
''I don't have a fault for them raising the bar. I do think it's unfortunate they didn't raise the dosage," said Blumenthal, who has been taking the extract for about a decade.
Bent said researchers 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 of saw palmetto.
''Now that this study is negative, I think it's reasonable to try a higher dose," said Bent.
A larger study of such herbal remedies is being planned.