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JAMA reviews 18 controlled studies on saw palmetto

Male readers will be pleased to know that the Journal of the American Medical Association recently published a favorable review on saw palmetto (Serenoa repens [Bartram] Small, Arecaceae) for relieving the uncomfortable urinary symptoms of benign prostatic hyperplasia (BPH). Symptoms of BPH, such as difficult urination and more frequent nighttime urination, affect roughly 50 percent of American men between the ages of 40 and 59, at an annual treatment cost of more than $2 billion. In this review of 18 controlled clinical studies, the authors concluded that saw palmetto was more effective than placebo and just as effective as the standard drug finasteride (Proscar®) in relieving the symptoms of moderate BPH [Wilt et al., 1998]. The native American plant is also associated with fewer side effects and costs significantly less than conventional drug therapies. Currently, saw palmetto is the physician's first choice for treating benign prostatic hyperplasia in Germany and Austria.

Compared to previous reviews on saw palmetto, the selection criteria used for this paper were much more meticulous, including only those studies that were randomized, placebo-controlled, and lasted at least 30 days. The 2,939 men involved in the studies ranged in age from 40 to 88 years, with a mean age of 65 years. On average, the studies lasted nine weeks and employed a dosage of 160 mg of standardized saw palmetto extract twice daily. Overall, there was a 28 percent improvement in urinary symptom scale scores in men taking saw palmetto. More specifically, compared to placebo, saw palmetto improved nocturia (nighttime urination) by 25 percent, peak urine flow by 24 percent, mean urine flow by 28 percent, and residual urine volume (incomplete emptying of the bladder) by 43 percent compared. Saw palmetto was just as effective as finasteride in improving urological symptoms and flow measures. In general, the men taking saw palmetto were twice as satisfied with the results as the placebo group and reported fewer sexual complaints than those taking finasteride. Roughly five percent of men in the finasteride groups reported erectile dysfunction, compared to just one percent of men in the saw palmetto groups and 0.7 percent in the placebo groups.

Despite the careful selection and statistical analysis of studies for this article, the authors noted several problems in the review process. Inconsistencies in the way investigators reported their outcome data made it more difficult to quantify the results of multiple trials for this review. In addition, the studies employed different scales for measuring urological improvement, due to a lack of standard symptom scales at the time that most of the studies were conducted. The researchers were also inconsistent in reporting secondary outcomes, including nocturia, mean urine flow, residual volume, peak urine flow, and prostate size. Lastly, only two of the 18 studies included a follow-up period lasting at least six months.

The reviewers concluded with their "wish list" for future saw palmetto research, pointing out a need for long-term studies using standardized dosages of saw palmetto, validated symptom scales, and inclusion of all secondary measurements. They also see a need for comparisons between saw palmetto and other conventional drug therapies, as well as investigations of long-term safety and effectiveness. At this time, researchers do not know whether saw palmetto prevents long-term complications of benign prostatic hyperplasia, such as acute urinary retention, or if it reduces the need for surgery. - Krista Morien (HRF)

Full article $20 - Review Order
[Wilt TJ, Ishani A, Stark G, MacDonald R, Lau J, Mulrow C. Saw palmetto extracts for treatment of benign prostatic hyperplasia: a systematic review. JAMA 1998; 280 (18): 1604-1609.]

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