A detailed safety assessment of a saw palmetto extract.

2008-06
Complementary therapies in medicine 16(3)
- Andrew L Avins
- Stephen Bent
- Suzanne Staccone
- Evelyn Badua
- Amy Padula
- Harley Goldberg
- John Neuhaus
- Esther Hudes
- Katusto Shinohara
- Christopher Kane

PubMed: 18534327
DOI: 10.1016/j.ctim.2007.10.005

Study Design

Type: Randomized Controlled Trial (RCT)
Sample size: n = 225
Population: 225 men with moderate-to-severe symptoms of benign prostatic hyperplasia
Methods: Randomized clinical trial comparing a standardized extract of the saw palmetto berry (160 mg twice daily) with a placebo
Blinding: Double-blind
Duration: 1 year
Funding: Unclear

Large Human Trial

Background

Saw palmetto is commonly used by men for lower-urinary tract symptoms. Despite its widespread use, very little is known about the potential toxicity of this dietary supplement.

Methods

The Saw palmetto for Treatment of Enlarged Prostates (STEP) study was a randomized clinical trial performed among 225 men with moderate-to-severe symptoms of benign prostatic hyperplasia, comparing a standardized extract of the saw palmetto berry (160 mg twice daily) with a placebo over a 1-year period. As part of this study, detailed data were collected on serious and non-serious adverse events, sexual functioning, and laboratory tests of blood and urine. Between-group differences were assessed with mixed-effects regression models.

Results

There were no significant differences observed between the saw palmetto and placebo-allocated participants in the risk of suffering at least one serious adverse event (5.4% vs. 9.7%, respectively; p=0.31) or non-serious symptomatic adverse event (34.8% vs. 30.1%, p=0.48). There were few significant between-group differences in sexual functioning or for most laboratory analyses, with only small differences observed in changes over time in total bilirubin (p=0.001), potassium (p=0.03), and the incidence of glycosuria (0% in the saw palmetto group vs. 3.7% in the placebo group, p=0.05).

Conclusions

Despite careful assessment, no evidence for serious toxicity of saw palmetto was observed in this clinical trial. Given the sample size and length of this study, however, these data do not rule out potential rare adverse effects associated with the use of saw palmetto.

Research Insights

saw palmetto berry→Improved Sexual Function
There were few significant between-group differences in sexual functioning or for most laboratory analyses, with only small differences observed in changes over time in total bilirubin (p=0.001), potassium (p=0.03), and the incidence of glycosuria (0% in the saw palmetto group vs. 3.7% in the placebo group, p=0.05).
Effect
Neutral
Effect size
Small
Dose
160 mg twice daily
saw palmetto berry→Reduced Glycosuria
There were few significant between-group differences in sexual functioning or for most laboratory analyses, with only small differences observed in changes over time in total bilirubin (p=0.001), potassium (p=0.03), and the incidence of glycosuria (0% in the saw palmetto group vs. 3.7% in the placebo group, p=0.05).
Effect
Neutral
Effect size
Small
Dose
160 mg twice daily
saw palmetto berry→Reduced Lower Urinary Tract Symptom
There were no significant differences observed between the saw palmetto and placebo-allocated participants in the risk of suffering at least one serious adverse event (5.4% vs. 9.7%, respectively; p=0.31) or non-serious symptomatic adverse event (34.8% vs. 30.1%, p=0.48).
Effect
Neutral
Effect size
Small
Dose
160 mg twice daily
saw palmetto berry→Reduced Potassium Level
There were few significant between-group differences in sexual functioning or for most laboratory analyses, with only small differences observed in changes over time in total bilirubin (p=0.001), potassium (p=0.03), and the incidence of glycosuria (0% in the saw palmetto group vs. 3.7% in the placebo group, p=0.05).
Effect
Neutral
Effect size
Small
Dose
160 mg twice daily
saw palmetto berry→Reduced Total Bilirubin Level
There were few significant between-group differences in sexual functioning or for most laboratory analyses, with only small differences observed in changes over time in total bilirubin (p=0.001), potassium (p=0.03), and the incidence of glycosuria (0% in the saw palmetto group vs. 3.7% in the placebo group, p=0.05).
Effect
Neutral
Effect size
Small
Dose
160 mg twice daily

Adverse Events Reported

saw palmetto berry→potassium change
potassium (p=0.03)
Finding
Increased risk
Significant
Yes
saw palmetto berry→total bilirubin change
only small differences observed in changes over time in total bilirubin (p=0.001)
Finding
Increased risk
Magnitude
p=0.001
Significant
Yes
saw palmetto berry→total bilirubin increase
with only small differences observed in changes over time in total bilirubin (p=0.001)
Finding
Increased risk
Significant
Yes
saw palmetto berry→_overall non-serious symptomatic adverse events
There were no significant differences observed between the saw palmetto and placebo-allocated participants in the risk of suffering at least one serious adverse event (5.4% vs. 9.7%, respectively; p=0.31) or non-serious symptomatic adverse event (34.8% vs. 30.1%, p=0.48)
Finding
No significant difference
Magnitude
34.8% vs. 30.1%, p=0.48
Significant
No
saw palmetto berry→_overall serious adverse events
There were no significant differences observed between the saw palmetto and placebo-allocated participants in the risk of suffering at least one serious adverse event (5.4% vs. 9.7%, respectively; p=0.31)
Finding
No significant difference
Severity
Serious adverse event
Magnitude
5.4% vs. 9.7%, respectively; p=0.31
Significant
No
saw palmetto berry→_overall sexual functioning
There were few significant between-group differences in sexual functioning
Finding
No significant difference
Significant
No
saw palmetto berry→changes in sexual functioning
There were few significant between-group differences in sexual functioning
Finding
No significant difference
Significant
No
saw palmetto berry→non-serious symptomatic adverse events
or non-serious symptomatic adverse event (34.8% vs. 30.1%, p=0.48)
Finding
No significant difference
Magnitude
34.8% vs. 30.1%
Significant
No
saw palmetto berry→serious adverse events
There were no significant differences observed between the saw palmetto and placebo-allocated participants in the risk of suffering at least one serious adverse event (5.4% vs. 9.7%, respectively; p=0.31)
Finding
No significant difference
Severity
Serious adverse event
Magnitude
5.4% vs. 9.7%
Significant
No
saw palmetto berry→glycosuria
the incidence of glycosuria (0% in the saw palmetto group vs. 3.7% in the placebo group, p=0.05)
Finding
Reported
Magnitude
0% in the saw palmetto group vs. 3.7% in the placebo group
Significant
No