The 72-week study involving almost 380 men found no difference between placebo and saw palmetto groups for lower urinary tract symptoms (LUTS).
The study, published in the Journal of the American Medical Association, used increasing daily doses of a high-quality, well-characterized ethanolic saw palmetto berry extract by Germany’s RottaPharma.
"Astonishingly enough, there was not any measurable effect – either in benefits or in toxicity – with increasing doses of the supplement in comparison to placebo," said study co-author Dr Claus Roehrborn from UT Southwestern Medical Center.
Saw palmetto, extracted from the berries of a dwarf palm tree, (Serenoa repens (W. Bartram) Small (Arecaceae)) has a long history of use as a remedy for benign prostatic hyperplasia (BPH), a non-cancerous swelling in the prostate gland of older men.
The global market for saw palmetto extract is about $700 million a year, according to the researchers from UT Southwestern.
Mark Blumenthal, founder & executive director at the American Botanical Council (ABC), told NutraIngredients-USA that the study was large and well-designed using a high-quality, well-characterized ethanolic saw palmetto berry extract.
“The results of this trial are obviously disappointing for many people in the natural products community who have been recommending various saw palmetto products for many years, as well as many men, like myself, who have been employing a saw palmetto preparation to help manage symptoms of benign prostatic hyperplasia — particularly those of us who are deriving beneficial results,” said Blumenthal.
Duffy MacKay, ND, vice president, scientific and regulatory affairs for the Council for Responsible Nutrition (CRN), added that there is no clear explanation as to why the placebo group showed some improvement without intervention. However, “it is possible that both groups may have included men whose urinary tract symptoms were not actually related to an enlarged prostate”.
There is scientific support for the efficacy of the herbal: A meta-analysis of 18 clinical trials (JAMA, 1998, Vol. 280, pp. 1604-1609) reported positive results for urinary health and complications of BPH. This has been subsequently challenged by a review of 30 trials in the Cochrane Database of Systematic Reviews (2002 Iss. 3).
The new study adds to the question marks over the efficacy of saw palmetto berry extracts.
Led by Michael Barry, MD, of Massachusetts General Hospital, Boston, the researchers recruited 369 men, aged at least 45, with an American Urological Association Symptom Index score of between 8 and 24.
The participants were required to take 1, 2, and then 3 doses (320 mg/d) of saw palmetto extract or placebo, with dose increases at 24 and 48 weeks.
ABC’s Blumenthal notes that the dose-escalation aspect of the trial would remove potential criticism that might have otherwise been raised if only the 320mg daily dose had been used, producing a negative outcome compared to the placebo group.
Results showed that both placebo and saw palmetto groups displayed similar decreases in AUASI scores, said the researchers.
In addition, there were no differences between the groups for any of the secondary outcomes, said the researchers. These included measures of urinary bother, excessive urination at night, and indices of sexual function, continence, and sleep quality.
The researchers added that no clearly attributable adverse effects were identified.
Botanicals vs pharmaceuticals
CRN’s Dr MacKay also described the study as well-designed and well-executed. However, he said the results 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.
“As a general rule, the potency of botanical dietary supplements is lower than pharmaceutical products,” said Dr MacKay. “This helps account for the strong safety profile of dietary supplements, as reinforced by the lack of adverse effects in the study, making saw palmetto a safe choice.
“The lower potency of botanicals, however, results in less immediate and dramatic effects than one would expect with pharmaceutical interventions.
“Although this trial didn’t provide results as compelling as we would like to have seen, there are other studies on saw palmetto that have shown benefit.
“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,” added Dr MacKay.
Steven Dentali, PhD, chief science officer at the American Herbal Products Association (AHPA) added: “This finding highlights the importance of knowing what herbal preparations are doing in the body prior to designing and conducting large clinical trials so that when an efficacy study fails we have information to evaluate beside an ‘it didn't work’ message."
2011, Volume 306, Issue 12, Pages 1344-135
“Effect of Increasing Doses of Saw Palmetto Extract on Lower Urinary Tract Symptoms”
Authors: M.J. Barry, S. Meleth, J.Y. Lee, K.J. Kreder, A.L. Avins, J.C. Nickel, et al. for the Complementary and Alternative Medicine for Urological Symptoms (CAMUS) Study Group