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Saw Palmetto Fails to Improve Benign Prostatic Hyperplasia Reprinted from the NCI Cancer Bulletin, vol. 3/no. 7, Feb. 14, 2006 (see the current issue).
An extract of the saw palmetto plant was no more effective than a placebo in reducing symptoms associated with benign prostatic hyperplasia (BPH), a randomized clinical trial has found. BPH is caused by an enlarged prostate gland, and millions of older men, particularly in Europe, use over-the-counter saw palmetto products to treat the condition.
The double-blind, randomized trial included 225 men over age 49; half took 160 mg of saw palmetto twice daily, and the others a placebo. After a year, the groups were similar in lower urinary tract symptoms and other objective measures of BPH, the researchers report in the February 9, 2006, issue of the New England Journal of Medicine (see the journal abstract).
The study, led by Dr. Stephen Bent of the University of California, San Francisco, was funded by the National Institutes of Health and the National Center for Complementary and Alternative Medicine. The negative results contrast with a number of earlier studies suggesting that saw palmetto may improve urinary symptoms caused
by BPH.
To explain the discrepancy between the positive and negative findings, the researchers point out that some earlier studies had design flaws. In addition, the patients in the new study may have shared attributes that made them unlikely to respond to saw palmetto. Alternatively, the level of the active ingredient in their extract may have been too low to be effective (the active ingredient, if one exists, is not known).
The study was well designed, adequately powered, and avoided the pitfalls of previous studies by treating participants for a year, optimizing the consistency of the herbal product, and measuring the adequacy of blinding, an accompanying editorial notes. The authors raise the possibility, however, that a different preparation or dose of saw palmetto might have been effective.
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