Informed opinions from medical experts
Harvard Commentary: Questions About Saw Palmetto
By Harold J. DeMonaco, M.S.
Harvard Medical School
What is saw palmetto?
Saw palmetto is a dwarf palm tree that grows in the southern United States, from the Carolinas to Texas. Berries from the saw palmetto tree were used as early as the 1700s by American Indians to treat prostate enlargement (more accurately called benign prostatic hypertrophy) and erectile dysfunction.
What health claims are associated with saw palmetto?
Saw palmetto is claimed to be of use for the following:
To treat benign prostatic hypertrophy
To increase both libido and sperm production
To prevent hair loss in men
To cleanse the urinary tract
To increase breast size in women
The mechanism by which saw palmetto works for these disorders remains obscure, but it may be related to an anti-estrogenic effect, an anti-androgenic effect, an anti-inflammatory effect or a decrease in the protein in blood that binds to sex hormones.
Is there scientific evidence of saw palmetto’s effectiveness?
For a compound with as widespread a use (both in Europe and the United States), there is a paucity of well-constructed clinical trials — only 18 as of 1998. Only a limited number of studies have addressed the use of saw palmetto in the treatment of benign prostatic hypertrophy. Unfortunately, not all of the studies used similar methods of patient selection or a similar study design, so comparisons are difficult. However, a few conclusions can be drawn.
Saw palmetto appears to be as effective as finasteride (Proscar) in the relief of urinary tract symptoms in men with benign prostatic hypertrophy. Men taking saw palmetto had improved nocturia (excessive urination at night) and improved urine flow. The improvement in these symptoms, however, is not accompanied by a reduction in the size of the prostate.
Is saw palmetto safe to take?
Saw palmetto appears to be relatively safe. The two most frequently observed side effects are erectile dysfunction and gastrointestinal upset. There are no long-term safety data, however. The longest studies included only a six-month period of observation.
What is the correct dosage?
The dose of saw palmetto most frequently used in clinical trials was 160 milligrams of oil-based berry extract twice a day. Always look for a brand that standardizes the extract in terms of the amount of fatty acid and sterol (a type of steroid) content. Teas made from saw palmetto are of limited value because they do not contain oil-based fatty acids and sterols.
Who should use saw palmetto?
Saw palmetto extracts should be used only when a diagnosis of benign prostatic hypertrophy has been made by a qualified health care provider. The symptoms of benign prostatic hypertrophy mirror those of prostatitis (inflammation of the prostate, sometimes caused by a bacterial infection) and prostate cancer. Because of this overlap, self-diagnosis and treatment are not recommended.
Harold J. DeMonaco, M.S. is the director of Drug Therapy Management and the chair of the Human Research Committee at the Massachusetts General Hospital. He is author of over 20 publications in the pharmacy and medical literature and routinely reviews manuscript submissions for eight medical journals.
This interview is not intended to provide advice on personal medical matters, nor is it intended to be a substitute for consultation with a physician.