Study Questions Saw Palmetto Efficacy

CHICAGOIncreasing the dose of saw palmetto did not reduce urinary problems for men with enlarged prostate glands in a new Journal of American Medical Association (JAMA) study (2011;306(12):1344-1351). Researchers at the Massachusetts General Hospital, Boston, reported Saw palmetto extract was no more effective than placebo for any outcome they measured.

Saw palmetto fruit extracts are widely used for treating lower urinary tract symptoms attributed to benign prostatic hyperplasia (BPH); and were the among the top herbal purchases in the United States in 2010.

The double blind, multicenter, placebo- controlled, randomized trial at 11 North American clinical sites was conducted between June 5, 2008, and Oct. 10, 2010, and included 369 men aged 45 years or older, with a peak urinary flow rate of at least 4 mL/s and an American Urological Association Symptom Index (AUASI) score of between eight and 24 at two screening visits. AUASI is a self-administered seven-item index assessing frequency of lower urinary tract symptoms with a range of 0 to 35 points.

The men were given one, two and then three doses (320 mg/d) of saw palmetto extract (Serenoa repens, from saw palmetto berries) in the form of chocolate-colored gelcaps or placebo, with dose increases at 24 and 48 weeks. The researchers noted the standard dose is 320 mg/d.

The researchers looked at several outcomes including difference in AUASI score between baseline and 72 weeks; urinary bother; nocturia(excessive urination at night); peak uroflow; postvoid residual volume; prostate-specific antigen level; participants global assessments; and indices of sexual function, continence, sleep quality and prostatitis symptoms.

However, the results showed no significant differences between baseline and 72 weeks or between the placebo and the control groups. Between baseline and 72 weeks, mean AUASI scores decreased from 14.42 to 12.22 points (-2.20 points) with saw palmetto extract, and from 14.69 to 11.70 points (-2.99 points) with placebo. The group mean difference in AUASI score change from baseline to 72 weeks between the saw palmetto extract and placebo groups was 0.79 points favoring placebo.

The proportion of participants achieving a three-point decrease in AUASI score at 72 weeks was 42.6 percent in the saw palmetto extract group and 44.2 percent in the placebo group," the authors wrote. In addition, the analysis of dose response also showed no greater improvement with saw palmetto extract vs. placebo at any dose level."

No clearly attributable adverse effects were identified.

The results of this sudy should not dissuade men experiencing urinary tract symptoms associated with an enlarged prostate gland (BPH) from considering saw palmetto as an option for reducing those symptoms, noted Duffy MacKay, N.D., vice president, scientific and regulatory affairs, the Council for Responsible Nutrition (CRN).

He said because both the placebo group and the treatment group saw improvements in their symptoms, interpreting the results may be difficult. "Although there is no clear explanation as to why the placebo group showed some improvement without intervention, it is possible that both groups may have included men whose urinary tract symptoms were not actually related to an enlarged prostate," he said. "Further, the trial might not have been large enough or long enough to have found a statistically significant benefit in the treatment group."

Further, he noted other studies on saw palmetto have shown benefits including inflammation reduction

"Saw palmetto extract in combination with other healthy habits, such as smart diet and regular exercise, is still a safe and viable option for men experiencing urinary discomfort associated with an ageing prostate," Duffy said.