Re: A Review of Adverse Events in the Use of Saw Palmetto: Safety Confirmed
Agbabiaka TB, Pittler MH, Wider B, Ernst E. Serenoa repens (saw palmetto). A systematic review of adverse events. Drug Safety. August 8, 2009;32(8): 637-647.
Saw palmetto (Serenoa repens) is a shrub or small tree in the palm family native
to the southeastern United
States. Today, extracts of dried saw
palmetto berries are used to treat lower urinary tract infections and benign
prostatic hyperplasia. Given the widespread use of saw palmetto, it is
important to investigate its safety. The purpose of this review article is to
describe the available human safety data on saw palmetto.
The literature review was conducted
by researchers at the Universities of Exeter and Plymouth
in Exeter, United
Kingdom and the Institute for Quality and Efficiency in
Health Care in Cologne, Germany. The researchers searched
the databases of MEDLINE, AMED, EMBASE, CINAHL, and the Cochrane Library, and
hand-searched the reference lists of all relevant articles. The researchers
also requested information from adverse event reporting systems in Australia, Germany,
the United States, and the United Kingdom; the World Health Organization;
manufacturers of saw palmetto products; and herbal organizations in the UK. The review
included all reports of human use of saw palmetto monopreparations. There were
no language restrictions, but data from animals, in vitro models, and human use
of combination products were not included in the review.
The search identified 140 articles,
of which 40 met the criteria for evaluation. These included 26 randomized
controlled trials, 4 non-randomized controlled trials, 6 uncontrolled trials,
and 4 case reports. The study population was primarily men diagnosed with
benign prostatic hyperplasia, prostate cancer, or lower urinary tract
infection, although two studies included women. Saw palmetto extract was
administered orally in daily doses ranging from 100 mg to 480 mg for durations
ranging from less than six months to more than two years. The World Health
Organization and national adverse event reporting systems received 389 adverse
event reports related to saw palmetto monopreparations. Only three of the 24
manufacturers responded and provided safety information, and none of the four
herbal organizations provided information.
The majority of adverse effects
reported were mild, infrequent, and reversible. The most frequently occurring
adverse events were abdominal pain, diarrhea, nausea, fatigue, headache,
decreased libido, and rhinitis. No drug interactions were reported for saw
palmetto.
The authors conclude that saw
palmetto is well tolerated and is not associated with serious adverse events. The
authors explain that the systematic evaluation of adverse events related to
herbal therapy is difficult. Data must be combined from very different types of
reports. There is no standard methodology to evaluate the findings, the quality
of the reporting is uneven, and pooling of data for statistical analysis is not
feasible. However, the combination of experimental studies and observational
data can be used to generate evidence needed to critically evaluate the safety of
an herbal therapy.