Variability in commercial ginseng products: an analysis of 25 preparations.

BACKGROUND: Because dietary supplements are not subject to the same regulations that pharmaceuticals are, there is concern among medical professionals that these products may lack purity or potency. OBJECTIVE: To determine the variability in a range of ginseng herbal products available in the United States, we identified and measured the concentration of marker compounds by using HPLC and liquid chromatography-tandem mass spectrometry. DESIGN: Twenty-five commercial ginseng preparations from the genera Panax or Eleutherococcus were obtained from a local health food store and analyzed for 7 ginsenosides (marker compounds for Panax species, which include Asian and American ginseng) and 2 eleutherosides (marker compounds for Eleutherococcus senticosus, also known as Siberian ginseng). RESULTS: All plant products were correctly identified by botanical plant species (ie, Panax species or E. senticosus); however, concentrations of marker compounds differed significantly from labeled amounts. There was also significant product-to-product variability: concentrations of ginsenosides varied by 15- and 36-fold in capsules and liquids, respectively, and concentrations of eleutherosides varied by 43- and 200-fold in capsules and liquids, respectively. Although a systematic search for adulterants was not conducted, review of the HPLC and liquid chromatography-tandem mass spectrometry data suggest that no substances other than ginsenosides or eleutherosides were extracted from the plant material. CONCLUSION: Our data suggest that US ginseng products are correctly labeled as to plant genus; however, variability in concentrations of marker compounds suggests that standardization may be necessary for quality assurance and that characterization of herbal products should be considered in the design and evaluation of studies on herbal products.