Saw palmetto flunks prostate exam

An herbal supplement used by 2.5 million men in the United States has failed to outperform a dummy capsule when taken for urinary problems.

Some men treat themselves for enlarged prostate glands by taking saw palmetto extract, which is derived from the berries of the North American scrub palm (Serenoa repens). The condition, called benign prostatic hyperplasia (BPH), squeezes the urethra, making urination difficult and frequent. Symptoms include a need to get up at night to urinate.

Several earlier studies showed that although saw palmetto didn’t shrink the prostate, it eased urinary symptoms somewhat. In one study, it relieved symptoms as well as did the drug finasteride, which doctors prescribe for BHP under the brand names Propecia and Proscar.

But in the Feb. 9 New England Journal of Medicine, scientists report that 112 men with BPH who took two capsules of saw palmetto extract daily for a year still had symptoms similar to those reported by 113 men with BPH who took inert capsules. The men weren’t told the contents of their capsules during the trial.

The active ingredient in saw palmetto is unknown, and preparations vary in content. That makes it hard to know whether these new results apply to all saw palmetto supplements, says study coauthor Stephen Bent, an internist at the Veterans Affairs Medical Center in San Francisco.

Nevertheless, the new study “tips the scale back toward uncertainty” about saw palmetto, he says.