Saw Palmetto Extract Ineffective Against Urinary Symptoms

Jim Kling

September 27, 2011

September 27, 2011 — Saw palmetto fruit extract was no better than placebo in the treatment of lower urinary tract symptoms in men with enlarged prostates, according to a study published in the September 28 issue of JAMA.

Saw palmetto extract is a popular alternative medicine for the relief of lower urinary tract symptoms in men with enlarged prostates. An effect could be a result of antiandrogenic, anti-inflammatory, and antiproliferative properties, but none of these mechanisms have been proven.

Previous trials of saw palmetto extract have yielded mixed results at standard doses (320 mg/day), with an early trial showing a positive effect, but more recent, larger trials showing none, write Michael J. Barry, MD, from the Department of Medicine, Massachusetts General Hospital, Boston, and colleagues.

Between June 2008 and October 2010, the researchers conducted a double-blind, placebo-controlled, randomized trial using up to 3 times the standard dose of the extract. Participants included 369 men aged 45 years or older. Patients had a peak urinary flow rate of at least 4 mL/second, an American Urological Association Symptom Index (AUASI) score between 8 and 24, and no exclusions.

Participants received 1 dose of the extract, then 2 doses at 24 weeks, and then 3 doses at 48 weeks. In the treated group, at 72 weeks there was a decrease of mean AUASI scores from 14.42 to 12.22 points (−2.20 points; 95% confidence interval [CI], −3.04 to −0.36 points) compared with a decrease from 14.69 to 11.70 points (−2.99 points; 95% CI, −3.81 to −2.17 points) in the placebo group.

The difference in AUASI score decline was 0.79 between the 2 groups (upper bound of the 1-sided 95% CI most favorable to saw palmetto extract was 1.77 points; 1-sided P = .91). The researchers observed no favorable effect of saw palmetto extract on any secondary outcomes, which included measures of urinary bother, nocturia, peak uroflow, postvoid residual volume, prostate-specific antigen level, participants' global assessments, sexual function, continence, sleep quality, and prostatitis symptoms.

The researchers also observed no adverse effects that could be attributed to saw palmetto extract.

Although the current study adds to the evidence that saw palmetto extract has no clinical benefit, men may continue to turn to it because natural remedies remain a popular alternative to prescription drugs, which can cause bothersome adverse effects such as sexual dysfunction, according to Allan Pantuck, MD, an associate professor of urology at the University of California, Los Angeles, David Geffen School of Medicine. Dr. Pantuck was not involved in the study.

Patients may perceive a benefit because the symptoms of an enlarged prostate can wax and wane over time. "When symptoms do lessen to some extent, people can attribute that improvement to the supplement, when this may just be the natural history of the disease. If patients didn't perceive some benefit from [saw palmetto extract], it wouldn't be so popular," Dr. Pantuck told Medscape Medical News.

The authors of the study report receiving grant money, royalties, or consultancy fees from, or holding stock options in, or other considerations from a number of pharmaceutical companies that market treatments for enlarged prostate, including Merck, GlaxoSmithKline, Pfizer, Watson, Astellas, Ferring, Taris, Triton, Farr Labs, Trillium, Cernelle, Johnson & Johnson, Amgen, Bayer, Caris, France Foundation, GenProbe, Steba Biotech, Ortho-Clinical Diagnostics, Envisioneering Medical, Viking Medical, Augmenix, Cambridge Endo, Myriad Genetics, Sanofi-Aventis, Lilly/ICOS, Allergan, and Neotract. Dr. Pantuck has disclosed no relevant financial relationships.

JAMA. 2011;12:1344-1351.

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