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Saw Palmetto Shrinks Prostate Tissues

In the first American randomized clinical trial of saw palmetto (Serenoa repens [Bartr.] Small, Arecaceae), the respected prostate herb proved beneficial in reducing swelling of prostate tissues in patients with benign prostatic hyperplasia (BPH). While numerous studies have confirmed the ability of saw palmetto extract (SPE) to reduce BPH symptoms, this is the first evidence that it actually shrinks enlarged prostate tissues (Overmyer, 1999).

The randomized, double-blind, placebo-controlled clinical trial involved 44 men with symptomatic prostate enlargement who took 320 mg of saw palmetto extract with nettle root extract or placebo for six months (Nutrilite® Saw Palmetto with Nettle Root, Nutrilite Division of Amway, Ada, MI). Researchers tested the participants for the usual clinical parameters, including International Prostate Symptom Score (IPSS), maximum urinary flow rate, residual urine volume, prostate volume, and prostate specific antigen (PSA, described below). Unlike previous research, this study included an ultrasound-guided prostate biopsy, allowing the scientists to assess changes in the participants' prostate tissue. Biopsies were taken at baseline and after six months of treatment.

As with previous research, SPE proved effective (or "somewhat effective," according to the researchers) in reducing overall symptom score and maximum urinary flow. Although symptom score (IPSS) dropped in the SPE group, it dropped similarly in the placebo group (2.9 and 2.6 respectively). The urinary flow rate increased in the SPE group while declining in the placebo group. There were no effects on hormone levels or other blood parameters.

The most intriguing part of this story is that SPE suppressed swelling of the prostate epithelium, causing a contraction in the tissues in the epithelium of the prostate and the transitional zone. Interestingly, SPE produced this benefit without affecting the levels of testosterone or dihydrotestosterone, which means that SPE works by an unidentified but non-hormonal mechanism. This is especially good news for men because conventional drug therapy for BPH frequently causes hormonal side effects, including reduced sex drive and performance. It should also be good news for doctors, because SPE did not affect the level of PSA in the blood. PSA tests are used to detect prostate cancer, and conventional therapy interferes with PSA testing by masking this early warning sign.

An editorial by Leonard Marks, M.D. accompanying the research report should provide perspective for physicians still uncertain about herbal therapies. "Saw palmetto extract (SPE) should now be considered a treatment option for men with symptomatic BPH, absent complications of the disorder. SPE is extremely safe; it is likely to exert positive effects; many patients want it; and more potent remedies, i.e., drugs or surgery, are generally not required in most BPH cases." Marks points out that saw palmetto has been used in Europe for generations, that its safety "has never been seriously questioned," and with the exception of occasional stomach upset, no side effects have been reported. "In particular, use of the extract has not been associated with erectile dysfunction, ejaculatory disturbance, or altered libido." - Rob McCaleb

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[Overmyer M. Saw palmetto shown to shrink prostatic epithelium. Urology Times 1999; 27(6): 1,42.]

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