Saw palmetto (also referred to as sabal or serenoa repens) is an evergreen palm that grows in the southeastern U.S. The berries of the plant are used medicinally. It has been used for centuries as a medicinal agent in urinary complications. Today, it is commonly used in men suffering from benign prostatic hyperplasia (BPH).

Uses and Clinical Applications for Saw Palmetto

Enlarged prostate (benign prostatic hypertrophy – BPH). Numerous human trials report that saw palmetto improves symptoms of benign prostatic hypertrophy (BPH) such as nighttime urination, urinary flow, and overall quality of life, although it may not greatly reduce the size of the prostate. The effectiveness may be similar to the medication finasteride (Proscar), but with fewer side effects.

Male-pattern hair loss. Saw palmetto may block some effects of testosterone and therefore reduce male pattern hair loss, similar to the medication finasteride (Propecia).

Other possible uses (based on tradition, scientific theories or limited research). Acne, anti-inflammatory, aphrodisiac, asthma, bladder inflammation, breast feeding, breast enlargement or reduction, bronchitis, cancer, cough, diabetes, digestive aid, diarrhea, excess hair growth, expectorant, high blood pressure, hormone imbalances (estrogen or testosterone), immune stimulation, impotence, indigestion, menstrual pain, migraine headache, muscle or intestinal spasms, ovarian cysts, pelvic pain, polycystic ovarian syndrome, postnasal drip, sedation, sexual vigor, sore throat, sperm production, testicular atrophy, upper respiratory tract infection, urinary antiseptic, uterine or vaginal disorders.

How Does Saw Palmetto Work?

Saw palmetto:

• has anti-androgenic and anti-estrogenic properties by direct action on cytosol and nuclear receptors and by inhibition of the enzyme testosterone-5-alpha-reductase.
• inhibits conversion of testosterone to dihydrotestosterone (DHT)
• inhibits DHT binding to cytosol androgen (male hormone) receptors and transport to the nucleus.
• has an anti-estrogenic effect as determined by receptor activity. Estrogen contributes to BPH by inhibiting hydroxylation and subsequent elimination of DHT.

Enlarged prostate (BPH) is thought to be caused by an increase in the conversion of testosterone to dihydrotestosterone (DHT) in the prostate. DHT stimulates the production of prostate cells. Excessive formation of DHT leads to overproduction and enlargement of the prostate (hyperplasia). Another factor is the presence of estrogen which inhibits the elimination of DHT. There are several reported mechanisms of action of saw palmetto for use in treating BPH. They include inhibition of DHT production, inhibition of the binding of DHT to its receptors and promoting its breakdown.

Also, saw palmetto is reported to exert an antiestrogenic effect, as well as an antiandrogenic effect. Some investigators believe that its antiestrogenic effect may be more important than any of its other actions. Saw palmetto inhibits 5-a reductase, an enzyme that catalyzes the conversion of testosterone into DHT, having alpha-1 and alpha-2 adrenergic blocking capabilities. Various clinical studies have reported the positive benefits of using standardized saw palmetto extracts in the prevention of BPH, and saw palmetto has compared favorably with finasteride in several studies.

Of interest is immune stimulating activity of polysaccharides found in the fruit of saw palmetto. In vitro, a water extract of saw palmetto produced an increase in phagocytic (white blood cell) activity by 36%. Also, in laboratory mice, the polysaccharide fraction of saw palmetto berry produced a much higher carbon clearance value than echinacea (Echinacea purpurea) or Siberian ginseng (Eleutherococcus senticosus) and showed a higher value than any of nine other plant extracts. However, the standardized and alcohol extracted preparations of saw palmetto are not extracted with water, so would not contain these immune stimulating polysaccharides – use encapsulated raw berries if you have an immune system concern.

Synergists: Saw palmetto works synergistically with zinc and essential fatty acids.

How Much Should You Take?

A standardized extract of saw palmetto containing 80% to 95% sterols and fatty acids (liposterolic content) is often recommended. Standardization involves measuring the amount of certain substances in products to try to make different preparations similar to each other.

The most common dosage is 160 mg. twice daily if you have prostate trouble. The daily dosage range is 80 – 320 mg.

Saw Palmetto Side Effects and Precautions

At recommended dosage levels, saw palmetto is considered safe. There is a very low incidence of headaches or gastrointestinal complaints if taken on an empty stomach.

Because of possible hormonal activity, saw palmetto is not recommended for women who are pregnant or breast-feeding.

There is little experience with hormone-dependent disorders other than prostate enlargement (BPH).

Drug Interactions

Constituents of saw palmetto berry have alpha-adrenergic blocking activity, which may alter the effects of these medications: prazosin, terazosin, doxazosin mesylate, tamsulosi.

Saw palmetto may have an additive effect if taken with drugs that affect the levels of male sex hormones (androgens), such as finasteride (Prosca, Propecia) or flutamide (Eulexin).

In theory, saw palmetto may interfere with birth control pills or hormone replacement therapy in women.

If you’re taking any of these drugs, check with your doctor or naturopathic physician before taking saw palmetto.

Because saw palmetto may have activity on the body’s response to estrogen, the effects of other agents believed to have estrogen-like properties may be altered. Possible examples include alfalfa, black cohosh, bloodroot, burdock, hops, kudzu, licorice, pomegranate, red clover, soy, thyme, white horehound, and yucca.