(Extraído de MedlinePlus)
For users reporting benefits, it's a classic placebo effect, experts say
Tuesday, September 27, 2011
TUESDAY, Sept. 27 (HealthDay News) -- For men suffering from urinary problems related to an enlarged prostate, saw palmetto extract doesn't seem to relieve symptoms any better than a placebo, even when taken at high doses, a new study finds.
Many men in the United States and Europe use plant extracts to relieve lower urinary tract symptoms related to benign prostatic hyperplasia (BPH), a condition that enlarges the prostate gland. Saw palmetto is the most commonly used extract, but its effectiveness has not been proven.
"Despite pushing the dose up to three times what's traditionally been used, we couldn't find the extract we studied lowered urinary tract symptoms more than placebo," said lead researcher Dr. Michael J. Barry, chief of the General Medicine Unit at Massachusetts General Hospital in Boston.
Men with BPH experience bothersome symptoms such as frequent urination, urgency and hesitation. Medical treatments include drugs, minimally invasive therapies or surgery, but natural treatments have a strong following.
A 2007 survey found that 17.7 percent of U.S. adults had used a natural product in the previous 30 days, and just over 5 percent had taken saw palmetto, the researchers said. The frequency among older men would be even higher, they added.
In the current study, no side effects were seen with saw palmetto extract, which is a plus. "With no side effects and some men getting improvement, there may be some men who want to give it a try to see if it will work for them even though it's no better than placebo," Barry said.
"For me, I don't think I would take it," he added.
The report was published in the Sept. 28 issue of the Journal of the American Medical Association.
For the study, Barry's team randomly assigned 369 men with BPH to increasing doses of saw palmetto extract or placebo. The men were 45 or older -- average age 61 -- and seen at 11 sites in North America between June 2008 and October 2010.
After 72 weeks of treatment, 42.6 percent of the men receiving saw palmetto extract had a 2.2 improvement in scores on the American Urological Association Symptom Index, while about 44 percent of men taking placebo showed about a 3-point improvement in their score, the researchers found.
Overall, there was a difference in the scores of 0.79 points in favor of the placebo, they added.
Even at the highest dose -- 960 milligrams -- saw palmetto fared no better than placebo. Also, saw palmetto extract was no better than placebo for any of the other outcomes, including measures of urinary bother, excessive urination at night, measures of sexual function, continence, sleep quality and symptoms of prostatitis (inflammation of the prostate).
"We've always known there's a pretty big placebo effect with lower urinary tract symptoms," Barry said.
There are different ways to extract chemicals from saw palmetto berries, and it's possible that another method -- or another extract -- might work, Barry said. "But, given the series of well-done negative studies, it's harder to think that someone will be able to find an extract that will work," he added.
Dr. Stephen Bent, an assistant professor of medicine at the University of California, San Francisco, who has done his own research on BPH and saw palmetto extract, said the study results didn't surprise him.
The findings from this study are "definitively negative," he said.
"When men try saw palmetto, chances are they are going to have some improvement, because they are going to experience a placebo effect," Bent said. "It may be that men get a benefit when they take a saw palmetto product, but it has nothing to do with saw palmetto."
SOURCES: Michael J. Barry, M.D., chief, General Medicine Unit, Massachusetts General Hospital, Boston; Stephen Bent, M.D., assistant professor, medicine, University of California, San Francisco; Sept. 28, 2011, Journal of the American Medical Association