Historical or traditional use (may or may not be supported by
scientific studies)
In the early part of the twentieth century,
saw palmetto berry tea was commonly recommended by herbalists
for a variety of urinary tract ailments in men. Some believed
the berry increased sperm production and sex drive in
men.
Active constituents
The liposterolic (fat-soluble)
extract of saw palmetto provides concentrated amounts of free
fatty acids and sterols. One study with a saw palmetto extract
suggests that it reduces the amount of dihydrotestosterone (DHT)
(an active form of testosterone) binding in the part of the
prostate surrounding the urethra (the tube carrying urine from
the bladder).1 Test tube studies also suggest that saw palmetto
weakly inhibits the action of 5-alpha-reductase, the enzyme
responsible for converting testosterone to DHT.2 In test tubes,
saw palmetto also inhibits the actions of growth factors and
inflammatory substances that may contribute to benign prostatic
hyperplasia (BPH). Contrary to some opinions, saw palmetto does
not have an estrogen-like effect in men’s bodies.
Over the
last decade, double-blind clinical trials have proven that 320
mg per day of the liposterolic extract of saw palmetto berries
is a safe and effective treatment for the symptoms of BPH. A
recent review of studies, published in the Journal of the
American Medical Association, concluded that saw palmetto
extract was as effective as finasteride (Proscar®) in the
treatment of BPH.3 The clinical effectiveness of saw palmetto
has been shown in trials lasting six months to three years.
A
three-year trial in Germany found that taking 160 mg of saw
palmetto extract twice daily reduced nighttime urination in 73%
of patients and improved urinary flow rates significantly.4 In a
double-blind trial, 160 mg of saw palmetto extract taken twice
daily was found to treat BPH as effectively as finasteride
(Proscar) without side effects, such as loss of libido.5
Saw
palmetto extract has also been combined with a nettle root
extract to successfully treat BPH. One trial using a combination
of saw palmetto extract (320 mg per day) and nettle root extract
(240 mg per day) showed positive actions on symptoms of BPH
(e.g. improved urine flow, decreased nighttime urination, etc.)
over a one-year treatment period.6 Another study compared the
same combination to finasteride for one year with positive
results.7
How much is usually taken?
For early-stage BPH,
160 mg per day of liposterolic saw palmetto herbal extract in
capsules is taken two times per day. One trial suggested that
320 mg once per day may be equally effective.8 It may take four
to six weeks to see results with BPH. If improvement is noted,
the saw palmetto should be used continuously. It is important to
work closely with a urologist to determine clinical improvement.
Although it has not been tested for efficacy, saw palmetto is
occasionally taken as a tea made with 5–6 grams of the powdered
dried fruit. Ground, nonstandardized berry preparations (1–2
grams per day) and liquid extracts of whole herb at 5–6 ml per
day are also sometimes used but have not been specifically
tested.
Are there any side effects or interactions?
No
significant side effects have been noted in clinical trials with
saw palmetto extracts. However, in rare cases, saw palmetto can
cause stomach problems,9 and one individual who was taking saw
palmetto developed severe bleeding during surgery.10 According
to some clinical trials, saw palmetto extract does not appear to
interfere with accurate measuring of prostate-specific antigen
(PSA)—a marker for prostate cancer.11 One test tube study found
that saw palmetto did not prevent the release of PSA from
prostate cells.12 Saw palmetto is most effective in managing
symptoms of BPH but has not been shown to aggressively shrink
the size of the prostate. BPH can only be diagnosed by a
physician (preferably a urologist). Use of saw palmetto extract
for BPH should only occur after a thorough workup and diagnosis
by a doctor. There are no proven uses of saw palmetto for
women.
At the time of writing, there were no well-known drug
interactions with saw palmetto.
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