Saw palmetto does nothing for enlarged prostates

Saw palmetto berry extract, an herbal supplement used by millions of men to treat the bothersome symptoms of an enlarged prostate, is largely ineffective for this purpose, a new study indicates.

Enlargement of the prostate - what doctors refer to as benign prostatic hyperplasia or BPH - is a common problem for older men. Some BPH symptoms include a weak urinary stream, inability to completely empty the bladder, and frequent nighttime trips to the bathroom.

Saw palmetto is often recommended as an alternative to FDA-approved drugs for BPH, based on a number of small studies showing it may help. But in a year-long study of 225 men over the age of 49 with moderate to severe symptoms of BPH, treatment with saw palmetto was not superior to placebo for improving urinary symptoms or objective measures of BPH.

Saw palmetto, 160 milligrams taken twice daily, did not increase urinary flow rates, reduce residual urinary volume after voiding, decrease the size of the prostate, or improve quality of life for the men in the study who took it, the study team reports in this week's New England Journal of Medicine.

"Subgroup analyses indicated that there was no benefit among patients with either more or less severe symptoms or among patients with either small or large prostate glands," they further report.

In an interview with Reuters Health, Dr. Stephen Bent of the San Francisco VA Medical Center and first author on the paper acknowledged that these findings were not what he expected.

"The weight of prior evidence suggests that saw palmetto is effective (for BPH)," Bent said. "There have been about 21 small trials and the majority of them showed some symptomatic benefit so we were expecting to find a benefit and we didn't."

So why the discrepant findings? "It's possible," said Bent, "that prior studies were not blinded properly," he explained, "Saw palmetto is a very pungent smelling, bad tasting herb, so it may have been that people in the placebo groups knew they were taking placebo and didn't get a placebo response whereas the saw palmetto group got a placebo response."

Summing up, he said: "Our study certainly sheds some doubt on the efficacy of saw palmetto (for BPH) and more work needs to be done to either confirm or contradict our findings."

In a commentary, Drs. Robert S. DiPaola and Ronald A. Morton of the University of Medicine and Dentistry of New Jersey remind consumers that herbs and other botanical products are not held to the same standards as FDA-approved drugs, a policy they call "misguided."

"Without the same oversight for herbal therapies, the public risks self-medication with substances that are potentially ineffective, toxic, or both," they write.

SOURCE: The New England Journal of Medicine, February 9, 2006.