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Saw Palmetto

Saw Palmetto is a fatty acid mix from Serenoa repens that has been touted for its abilities to increase testosterone (not effective) and suppress prostate growth (questionable effectiveness); safe for use in benign prostatic hyperplasia and abnormal urine flow rates in men, but studies have had mixed results in terms of efficacy.

Our evidence-based analysis on saw palmetto features 64 unique references to scientific papers.

Kamal Patel
Research analysis led by and reviewed by the Examine team.
Last Updated:

Summary of Saw Palmetto

Primary information, health benefits, side effects, usage, and other important details

Saw Palmetto is a supplement which is derived from the fruit of the plant Serenoa repens. The supplement (saw palmetto) has a caloric value, as it is rich in fatty acids.

Compounds in Saw Palmetto have the ability to block an enzyme that converts testosterone into dihydrotestosterone (DHT), the latter of which is more androgenic and can cause hair loss in the genetically susceptible. A couple of preliminary studies suggests Saw Palmetto supplementation can promote hair regrowth, though more research is needed before strong conclusions can be made.

Saw Palmetto's effects on DHT production have also led to saw palmetto being used for benign prostatic hyperplasia (BPH) and (LUTS) in men. Some studies have shown positive results, but larger and more well-designed studies have brought its efficacy into question.

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How to Take

Recommended dosage, active amounts, other details

While the active compound(s) are not yet known, it is known that they exist in what is known as the 'liposterolic' fraction of the fruits. If using saw palmetto choose a product that discloses the percentage of the supplement which is this fraction.

Supplementation of saw palmetto tends to be in the range of 160-320 mg, taken once daily, of a product which is 80-90% liposterolic compounds by weight. While it is not confirmed if saw palmetto needs to be taken with food due to the fat soluble nature of this fraction it is advised.

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Human Effect Matrix

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The Human Effect Matrix summarizes human studies to tell you what effects Saw Palmetto has on your body, how much evidence there is, and how strong these effects are.

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Grade Level of Evidence
Robust research conducted with repeated double-blind clinical trials
Multiple studies where at least two are double-blind and placebo controlled
Single double-blind study or multiple cohort studies
Uncontrolled or observational studies only
Level of Evidence
? The amount of high quality evidence. The more evidence, the more we can trust the results.
Outcome Magnitude of effect
? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
Notes
grade-b
Symptoms of Benign Prostatic Hyperplasia
Minor - See all 7 studies
Smaller, shorter trials have noted some effect, but larger, longer trials have noted no effect. The most recent Cochrane meta-analysis also notes no effect.
grade-c
DHT
- - See study
grade-c
Prostate Specific Antigen
Low See all 4 studies
While observational data suggests a decrease, trials have found no change in PSA levels.
grade-c
Testosterone
- Very High See 2 studies
grade-d
Quality of Life
Notable Moderate See 2 studies
grade-d
Hair Regrowth
Minor - See study
Saw palmetto usage over two years (320mg) appears to increase hair growth on the crown in 38% of users with male pattern baldness, a response rate that was less than 1mg finasteride (benefiting 66% of users and also improving hair growth in the frontal region).
grade-d
Sexual Function
Minor Low See all 4 studies
While observational and smaller interventional studies have found some effect, larger and longer trials have not.

Studies Excluded from Consideration

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Things to Note

Is a Form Of

Primary Function:

Also Known As

Serenoa Repens

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This page is regularly updated, to include the most recently available clinical trial evidence.

Each member of our research team is required to have no conflicts of interest, including with supplement manufacturers, food companies, and industry funders. The team includes nutrition researchers, registered dietitians, physicians, and pharmacists. We have a strict editorial process.

This page features 64 references. All factual claims are followed by specifically-applicable references. Click here to see the full set of research information and references for Saw Palmetto.

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