A US study revealed that an herbal supplement that is widely sold in the United States and Europe to relieve urinary symptoms in men with an enlarged prostate has no benefit over a placebo.
The global market for saw palmetto extract is about $700 million a year, but a randomized trial at 11 sites in North America showed that even triple doses of the over-the-counter drug neither worked nor harmed the patients.
"Astonishingly enough, there was not any measurable effect -- either in benefits or in toxicity -- with increasing doses of the supplement in comparison to placebo," said co-author Claus Roehrborn, chairman of urology at University of Texas Southwestern.
"These supplements are apparently not doing anything measurably above and beyond what we call the placebo effect," said Roehrborn of the research in the latest edition of the Journal of the American Medical Association.
Led by Michael Barry of Massachusetts General Hospital in Boston, researchers followed 379 men age 45 and older whose symptoms included difficulty emptying their bladders, weak and/or frequent urination.
As part of the randomized trial, some received saw palmetto extract -- which comes from the berries of the saw palmetto dwarf plant tree -- and others were given a sugar pill that smelled and tasted the same.
Measurements showed the drug, even when increased in dosage over 72 weeks, had no impact on urinary symptoms such as nighttime urination or incontinence, and did not improve sexual function or allow men to sleep better.
"None of them showed any effect whatsoever in contrast to placebo," Dr. Roehrborn said. "These supplements cost about $30 or more a month, and they obviously don't help."
Enlarged prostate is a common condition of aging that affects about half of men in the United States over age 50, and 75 percent by age 80.
The growth of the prostate can make it difficult to urinate and can cause urinary tract infections.
Medication and surgery are some of the treatment options, though herbal supplements with anti-inflammatory properties have also been widely used for decades in the belief that they can ease symptoms.
The men in the study did tend to experience a slight improvement in symptoms, but the trend was observed in both groups.
"We commonly see this in clinical trials," said co-author Gerald Andriole, chief of urologic surgery at Washington University School of Medicine in St. Louis.
"Patients often report an improvement in symptoms because they are taking something, even if it is a placebo. But in this study, there was no benefit to taking saw palmetto over the placebo."
The research was conducted under an investigational new drug application from the Food and Drug Administration, and was funded by the National Institutes of Health and the National Center for Complementary and Alternative Medicine.
The saw palmetto pills and placebos were donated for the study by Rottapharm/Madaus in Cologne, Germany.