(CBS) Saw palmetto offers no relief from symptoms of prostate enlargement, a.k.a. benign prostatic hyperplasia (BPH).
That's the stark finding of a new study that tested the popular herbal remedy in men suffering from BPH, which causes urinary symptoms like a weak or intermittent stream, difficulty urinating, and having to make frequent trips to the bathroom, especially at night.
The study may settle a longstanding debate over the effectiveness of saw palmetto, which is especially popular in Europe. Previous studies produced conflicting results, but none had tested the herb at high doses, according to a written statement issued by Washington University School of Medicine in St. Louis.
But in this study - published in the Sept. 28 issue of the Journal of the American Medical Association - men took up to three times the standard dosage of saw palmetto - and the stuff still didn't work.
"Now we know that even very high doses of saw palmetto make absolutely no difference," study co-author Dr. Gerald Andriole, MD, chief of urologic surgery at the school, said in the statement. "Men should not spend their money on this herbal supplement as a way to reduce symptoms of enlarged prostate because it clearly does not work any better than a sugar pill."
The study involved more than 300 men age 45 or older who had moderate symptoms of BPH. Some men were given a daily dose of saw palmetto extract. Others got an identical-looking placebo pill. The researchers followed the men for nearly 17 months, as the dosage of saw palmetto kept rising.
What happened? The men taking saw palmetto noticed a slight improvement in their symptoms - but so did the men who had been taking a placebo.
BPH is a common condition, affecting more than half of men in their sixties and up to 90 percent of men in their seventies and eighties. Its cause is poorly understood. Treatments include drug therapy - commonly with so-called "alpha-blocking" drugs - and a variety of surgical techniques, including some minimally invasive ones in instruments are inserted into the urethra.
The National Kidney & Urological Diseases Information Clearinghouse has more on prostate enlargement.