What is saw palmetto?

Saw Palmetto (Serenoa repens) is a plant that grows in the southeastern United States, and its berries have been used for medicinal purposes for centuries. It is commonly used to treat symptoms of an enlarged prostate and for conditions affecting the urinary tract.

How does it work?

The exact mechanism by which saw palmetto works for medicinal purposes is not completely understood. However, it is believed to work by reducing the production of dihydrotestosterone (DHT), which is a hormone that can cause prostate growth. Additionally, saw palmetto may also have anti-inflammatory and antioxidant effects.

What are the active ingredients that are important for its medicinal properties?

The active ingredients in saw palmetto that are important for its medicinal properties include fatty acids and phytosterols.

What forms does it come in?

Saw palmetto is available in a variety of forms, including capsules, tablets, tinctures, and extracts.

When was it first used for medicinal purposes?

The first use of saw palmetto for medicinal purposes dates back to the indigenous people of the southeastern United States, who used the berries for various conditions. However, its use as a treatment for symptoms of an enlarged prostate became more widespread in the 20th century.

What does Saw Palmetto help with?

Saw palmetto is a small palm tree from the southeast United States. Native American healers used its berries for urinary and male health. Today the berry extract is sold as a capsule or soft gel.

• An enlarged prostate (BPH) making it hard to pee
  Good evidence — several human trials; this is the most studied use in our file. In these trials, many men reported better flow and fewer symptoms. The change came over a few months of daily use, not days. Our file does not record the size or dose of each trial, so we do not state them.
  Evidence grade B · Traditional tier T2
• Waking up at night to pee
  Good evidence — several trials of a standardised berry extract. Waking two or more times a night to pee is called nocturia. In several trials, men taking a standardised extract made fewer night trips. The file does not record how many men took part, or at what dose.
  Evidence grade B · Traditional tier T2
• A weak or slow urine stream
  Early evidence — clinical studies of men, with sizes and doses not on file. An enlarged prostate presses on the urethra and narrows it. In these studies, men reported better peak flow after steady use. In lab work, the extract eased swelling and relaxed muscle a little.
  Evidence grade C · Traditional tier T2
• Male-pattern hair loss
  Early evidence — early, small human studies. Male-pattern baldness is driven by DHT, a strong form of testosterone. In lab studies, saw palmetto slowed the enzyme that makes DHT. Early human studies point to slower loss, and slightly thicker hair at the crown in some men.
  Evidence grade C · Traditional tier T2
• Long-term prostate swelling (prostatitis)
  Long traditional use · not yet tested in trials — user reports and lab work; no clear human trial on file. Some men with pelvic pain and burning have reported relief with regular use. In lab work, the extract lowered the activity of swelling-related compounds in prostate tissue. Our file holds no trial size or dose for this use.
  Evidence grade D · Traditional tier T2
• Pelvic pain in men
  Long traditional use · not yet tested in trials — limited, mixed results in men with chronic pelvic pain. Some men with chronic pelvic pain reported less discomfort. The reports came from care that mixed saw palmetto with other steps. So we cannot say how much came from the berry alone.
  Evidence grade D · Traditional tier T2
• Sudden urges to pee, or a bladder that feels full again right away
  Long traditional use · not yet tested in trials — no human study on file for this use by itself. Some men on saw palmetto for BPH report fewer urges and fewer daytime trips. But our file holds no trial that tested urgency on its own. The proposed action is on hormones and on bladder muscle tone.
  Evidence grade insufficient · Traditional tier T2
• High DHT levels
  Long traditional use · not yet tested in trials — lab studies of the enzyme only. In lab studies, saw palmetto slowed 5-alpha reductase. That enzyme turns testosterone into DHT. Our file holds no human trial that measured DHT levels before and after.
  Evidence grade insufficient · Traditional tier T2
• Hormone balance as men age
  Long traditional use · not yet tested in trials — practitioner use and tradition, with no human trial on file. Some practitioners use it when DHT-linked signs show up with normal testosterone. Those signs include prostate growth and thinning hair. Our file records no human trial of hormone ratios, so this rests on practice alone.
  Evidence grade insufficient · Traditional tier T2

What Saw Palmetto has not been shown to do

• It has not been shown to raise testosterone or build muscle; the work on file points to little change in overall testosterone.
• It has not been shown to prevent or treat prostate cancer; our file holds no human study on cancer at all.
• It has not been shown to regrow a full head of hair; the best reports were modest gains at the crown.
• It has not been shown to shrink an enlarged prostate back to normal size; the gains men reported were in symptoms.
• It has not been shown to clear an infection of the prostate, and our file holds no human study on that.
• It has not been shown to help urinary problems in women; every study on file was done in men.
• It has not been shown to work fast; men in trials reported change over months, not over days.

How to read this:

The grades here rate the human evidence for each use, not how strong the product is. A means steady results across randomised human trials. B means at least one good human trial. C means small or early human studies. D means the human evidence is weak or split. Insufficient means no human study on file, only lab work or long use. Saw palmetto has one overall grade of B, but its uses do not all rest on the same proof. This page lists options and what studies found. It is not medical advice, and it is not a promise of results. Talk with your own doctor about urinary or prostate changes.

What can it help prevent?

Saw palmetto has not been proven to help prevent any specific conditions or symptoms.

Which foods are rich in it?

Saw palmetto is not commonly found in food sources.

What are possible side effects?

Saw palmetto is generally well-tolerated, but some possible side effects include:

• Gastrointestinal side effects: Nausea, indigestion, and stomach upset.
• Sexual side effects: Decreased sex drive, impotence, and reduced sperm production.
• Allergic reactions: Rashes, itching, and hives.

What’s the recommended daily dose?

The recommended daily dose of saw palmetto for adults is 320 mg to 640 mg per day, taken in divided doses.

How many days does it take to work?

It may take several weeks to several months for saw palmetto to take effect.

What time of day is best to take it?

It is recommended to take saw palmetto at the same time each day, either in the morning or evening.

Is it best to take it with or without food?

It is best to take saw palmetto with food to reduce the risk of gastrointestinal side effects.