Saw palmetto shown to

shrink prostatic epithelium

Double-blink study suggest herb offers clinical benefits, but more data are needed

By Mac Overmyer

Dallas— A multi-center study of the effects of saw palmetto on BPH is too small to support solid conclusions, but the results may have substantial implications for clinical practice, pharmaceutical economics, and research.

Data from the randomized, double-blind study of 44 men presented at the AUA meeting here suggest only that the herb can produce clinical benefits. However, biopsied tissue sampled before and after treatment showed clear-cut evidence that the active ingredients in saw palmetto reduce the size of epithelial tissue, particularly in the transition zone.

Moreover, the findings also suggest the plant, grown primarily in southern Florida, contains something with a mechanism or mechanisms unrelated to those of current pharmaceutical therapies such as 5-alpha-reductase inhibitors and alpha blockers.

"We didn't have enough people in this study to draw conclusions from typical BPH symptom endpoint data, such as symptom score, maximum flow, and residual urine," investigator Leonard S. Marks, MD, founder of the Urological Sciences Research Foundation (USRF), Culver City, CA, and clinical associate professor of urology at UCLA, told Urology Times. "We acquired that data, but it was almost incidental because we had only 44 men."

Patients were examined at the USRF, and results of the study can be found on the USRF web site at www.usrf.org

Symptom scores declined a statistically insignificant 2.9 points among men taking saw palmetto and 2.6 points in the placebo group. Dr. Marks, who presented one of two papers on the study, noted that studies of pharmaceutical therapies for BPH traditionally produce large placebo effects, adding that "even in studies in which far more powerful substances are used, the improvements are not huge."

A search of the literature indicates Dr. Marks is correct in his observation. A recent double-blind, placebo-controlled study of finasteride in some 3,000 men, for example, showed a mean decrease in symptom score of 3.3 points among treated patients and 1.3 points in the placebo arm (N Engl J Med 1998; 338:557-63).

Significant pathological effects
Histologic and morphologic examination of tissue samples taken before and after saw palmetto treatment yielded much stronger findings. A research team at Johns Hopkins University, Baltimore, working with Dr. Marks found that tissue in the transition zone epithelium was reduced from 17.8% to 10.7% after 6 months of herbal therapy. There were no major histologic or morphologic changes in the control group.

"What appears to happen is that there is a greater atrophy in saw palmetto-treated patients," said Jonathan Epstein, MD, professor of pathology, urology, and oncology at Johns Hopkins. "We define atrophy here as a shrinkage of the cytoplasm in relation to the nucleus. This is relative to the atrophy in the placebo group."

Several other findings by the UCLA and Johns Hopkins groups may have clinical implications. For instance, only one adverse effect was noted among men taking saw palmetto. It was a mild gastrointestinal disturbance, indicating the herbal remedy is relatively innocuous, at least in the short term. None of the patients experienced sexual side effects.

The second observation was that 19 of 21 patients (90.5%) receiving saw palmetto elected to continue the therapy when seals were broken at the conclusion of the trial. These men are being followed. All of the placebo recipients elected to begin treatment with the extract as well.

The herb apparently had no effect on prostatic androgen metabolism or apoptosis markers, suggesting that its effects are mediated by an unidentified, non-hormonal mechanism. Finasteride, on the other hand, is an inhibitor of 5-alpha reductase, while alpha blockers relax smooth muscle tissue. There is still concern among urologists, however, that saw palmetto may skew PSA screening results.

The UCLA/Johns Hopkins study does not address the issue of quality control that plagues most so-called "natural" remedies. No company can guarantee that the quantity of active ingredients is stable from lot to lot when the active ingredients are unknown. Saw palmetto is largely harvested by hand, and its berries are gathered, dried, and shipped to processing plants along with some stems and refuse.

Burgeoning market
Given the demand for BPH remedies, the energetic search for saw palmetto's active ingredients and mechanisms of action will likely accelerate. The Agency for Health Care Policy and Research estimates that 5.9 million men aged 50 to 79 might be candidates for some form of BPH therapy, and that this number will approach 12 million in the next two decades (Arch Intern Med 1995; 155:477-81).

A 1996 study found that approximately half the men with moderate so severe BPH symptoms discussed them with their family physicians (J Gen Intern Med 1996; 513-8), suggesting that many men are either bearing symptoms in silence or are self-medicating with herbal remedies. Rising health care costs are also pushing many toward herbal remedies and prompting many physicians to recommend them.

"Saw palmetto extract appears so he a reasonable treatment option for men with uncomplicated, symptomatic BPH," said Dr. Marks. "In a study presented by Glenn S. Gerber, MD [of the University of Chicago] at the AUA meeting last year, 24% of men receiving conventional or traditional therapy for BPH were also found to be using herbal therapy concomitantly."

The use of saw palmetto to treat BPH has been documented since the turn of the century. It has been used heavily in Europe for the last 20 years, but the lack of sound clinical studies led many to dismiss reports of its benefits. Still, that hasn't prevented many saw palmetto extract distributors from lauding the product's widespread use in Europe in promotional campaigns.

Even a decade ago, saw palmetto was considered little more than a weed in southern Florida and sold for about 12 cents per pound. Nowadays, it goes for up to $3.00 a pound.

In fact, the demand for saw palmetto has prompted the University of Florida to embark on a 3-year agricultural study of its cultivation and harvesting. The plant is slow-growing but naturally resistant to drought and needs no fertilizer. Florida state officials are concerned about the effect of indiscriminate saw palmetto harvesting on indigenous wildlife and ecosystems. If they decide to slow production and processing, the decision would have obvious effects on the amount of the herb available for clinical use.

The UCLA/Johns Hopkins study was funded by Nutrilite, a subsidiary of the Amway Corp., Ada, MI

This article was originally published in Urology Times, Vol. 27, No. 6, June 1999, pp. 1, 42.

Last modified: November 26, 2001

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