Drug Profile

Do Not Use: There is no evidence that this supplement is effective.

Background

Saw palmetto is the popular name for an extract of the dried berry of the dwarf palm tree Serenoa repens, which grows in the southeastern U.S. The berry is rich in fatty acids and sitosterols, and the latter are thought to constitute the active ingredient.Saw palmetto is especially popular in Europe but has enjoyed increased attention in the U.S. over the past decade.

A product called PC Spes contained saw palmetto as well as seven other herbs and was used to treat prostate cancer, despite never being subjected to a controlled trial.[1] It was shown to have estrogen-like activity and to depress prostate-specific antigen (PSA) levels, which could interfere with detection and treatment monitoring for prostate cancer.[2] It was removed from the market in 2002, as it was contaminated with the anticoagulant warfarin (COUMADIN).[3] Earlier, several lots of the preparation had been contaminated with the nonsteroidal anti-inflammatory drug indomethacin (INDOCIN) and diethylstilbestrol (DES), a known carcinogen and cause of birth defects.[4]

There is no convincing evidence that saw palmetto is effective for treating BPH. Moreover, there are other medications with proven effectiveness for BPH.[5]

Claimed uses

Benign prostatic hyperplasia (BPH)

BPH is a condition in which the prostate gland, which provides liquid components of seminal fluid, becomes enlarged. The condition is distinct from prostate cancer, hence the designation “benign.” The urethra is the tube that carries urine out of the body. Because it passes through the prostate, if that gland becomes enlarged (hyperplastic), it might block or restrict the passage of urine, resulting in incomplete emptying of the bladder. The symptoms of BPH vary, but the most common ones involve changes or problems with urination, such as a hesitant, interrupted, weak stream; urgency and leaking or dribbling; and more frequent urination, especially at night.

Side effects

Headache, gastrointestinal upset, high blood pressure, impotence, and decreased sex drive have been reported in patients taking saw palmetto.[6] Saw palmetto has been associated with a case of severe bleeding into the brain following surgery.[7] 

Interactions with other drugs

No interactions with other drugs have been reported, but this has not been studied formally.

Studies show

Saw palmetto has been promoted to relieve the symptoms of BPH. The primary evidence for this claim is a meta-analysis (a statistical combining of other studies) based on randomized, controlled trials. This meta-analysis was first published in 1998[8]but has since been updated online.[9]The most recent review concludes that saw palmetto provides “mild to moderate improvement in urinary symptoms and flow measures.” (Another, less extensive meta-analysis covering many of the same trials reached a similar conclusion but is not analyzed in detail here.[10]) It claims effectiveness similar to finasteride (PROSCAR), with fewer adverse effects.

Closer examination of the available data does not support this conclusion. First, of 21 studies included in the meta-analysis, only six used an accepted symptom scale, and five of those six did not have a placebo control and/or tested herbal combinations that included saw palmetto, making it impossible to ascribe any effect to saw palmetto itself. Such products should not be included in meta-analyses. Second, the studies were of short duration, with three-quarters of the studies lasting 13 weeks or less.

Third, most of the data in the meta-analysis come from old, poorly conducted studies published in inaccessible journals. Of the 21 studies, just one involved saw palmetto only, had a placebo control and was published in a journal accessible after 1987.[11] After six months, this study showed an improvement of 2.2 points — on a 36-point scale (6 percent) — over the placebo. Saw palmetto had no impact upon urinary flow rates, a more objective measure of drug effectiveness.

More fundamentally, no saw palmetto study has ever shown an impact upon the development of urinary obstruction or upon the need for surgery to relieve the symptoms of BPH.[12]

Research published in The New England Journal of Medicine found that saw palmetto was no more effective than an inactive placebo in treating the symptoms of an enlarged prostate gland.[13]

The Journal of the American Medical Association published an article in September 2011 with information from a double-blind, multicenter, placebo-controlled, randomized clinical trial on the effect of increasing the dose of saw palmetto in treating lower urinary tract symptoms in patients with BPH. The study was funded by the NIH and the National Center for Complementary and Alternative Medicine. The results of the study found that increasing the dose of saw palmetto did not decrease symptoms in these patients.

A recent Journal of Parenteral and Enteral Nutrition (JPEN) systematic review revealed that, with a few possible exceptions, dietary supplements offer no benefits to well-nourished adults eating a Western diet and, in many cases, may be harmful. The results of this study reinforce Worst Pills, Best Pills News’ longstanding view that there is little evidence that dietary supplements are either safe or effective.

The study authors concluded that with the possible exception of vitamin D in elderly patients and omega-3 fatty acids in patients with a history of cardiovascular disease, no data support the widespread use of dietary supplements in the U.S. and other Western countries. Indeed, the data suggest that certain commonly used dietary supplements, including beta-carotene, vitamin A and vitamin E, may be harmful. We agree.[14]