saw palmetto fruit include flavonoids, polyisoprenoids, and saccharides. The identity of the biologically active constituents has not been firmly established. Preparations of saw palmetto powdered fruit and saw palmetto extracts are typically analyzed for fatty acid content. Currently, the majority of saw palmetto is obtained from the southern coastal United States. It should be noted that the chemical profile of any plant may vary substantially if it is collected from a significantly different environment.
The typical daily amount ingested (usually by men with benign prostatic hyperplasia) is 320 mg of lipid/sterol extract of saw palmetto (LESP). The historical use of the plant was limited to whole fruit and teas; however, current widespread usage is primarily as the LESP. There are also blended products that include saw palmetto as one ingredient in a sometimes complex mixture of botanical or other ingredients. One such blend, PC-SPES, was found to be contaminated with the drug warfarin and was voluntarily withdrawn from the market in 2002. The safety/toxicity of blended products is not addressed in this prototype monograph, although the information about such combinations was considered to determine if it was relevant to the safety of saw palmetto.
The evidence regarding the safety of saw palmetto extracts was derived from nine randomized, double-blind, placebo-controlled clinical trials and three reference-controlled human clinical trials. It should be pointed out that these studies used a variety of preparations of saw palmetto fruit extracts. Numerous other studies have been conducted, but their usefulness was limited by publication in foreign languages, deficiencies in experimental design, or deficiencies in the published record. There has been one clinical case report of a serious adverse effect (hemorrhage during an operative procedure) possibly associated with saw palmetto consumption; however, the specific preparation or product and dosage were not reported and the symptoms could be consistent with a contaminated blended product, such as contamination by the anticoagulant warfarin. Although there have been four Special Nutrition/Adverse Event Monitoring System reports, there was no indication of clear causal relationships with saw palmetto. To date, there have been no reports of studies on drug interactions.
Some animal studies showed antiandrogenic effects on hyperplasia. These effects themselves were not considered to have serious implications to the safety of saw palmetto in older men, but they are consistent with saw palmetto being bioavailable and bioactive following oral ingestion and are consistent with saw palmetto’s purported beneficial antiandrogenic effects in humans. Also consistent are in vitro studies demonstrating some biological effects such as inhibition of steroid 5-α-reductase and antagonism of α1-adrenergic receptors.
Of the chemical constituents known to be present in saw palmetto fruit,