A detailed safety assessment of a saw palmetto extract.
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.
Division of Research, Northern California Kaiser Permanente, San Francisco, CA, USA. andrew.avins@ucsf.edu <andrew.avins@ucsf.edu>
Andrew L
AL
Avins
Stephen
S
Bent
Suzanne
S
Staccone
Evelyn
E
Badua
Amy
A
Padula
Harley
H
Goldberg
John
J
Neuhaus
Esther
E
Hudes
Katusto
K
Shinohara
Christopher
C
Kane
D000368:Aged; D004311:Double-Blind Method; D064420:Drug-Related Side Effects and Adverse Reactions; D006801:Humans; D008297:Male; D008875:Middle Aged; D008517:Phytotherapy; D010936:Plant Extracts / Q000009:adverse effects* / Q000494:pharmacology / Q000627:therapeutic use; D017430:Prostate-Specific Antigen / Q000187:drug effects; D011470:Prostatic Hyperplasia / Q000150:complications / Q000188:drug therapy*; D012044:Regression Analysis; D028024:Serenoa; D019529:Sexuality / Q000187:drug effects
D010936:Plant Extracts; D017430:Prostate-Specific Antigen; C040972:saw palmetto extract