Arch Intern Med 2003 (Mar 24); 163 (6): 699–704
Gilroy CM, Steiner JF, Byers T, Shapiro H, Georgian W
Department of General Internal Medicine,
University of Colorado Health Sciences Center,
Background: Echinacea sales represent 10% of the dietary supplement market
in the United States, but there is no guarantee as to the content, quality, variability, or contamination in Echinacea preparations.
Objective: To qualitatively and quantitatively assess the contents of
Echinacea-only preparations available in a retail setting.
Methods: One of each single-herb Echinacea preparations that were
available in August 2000 was obtained from several stores in the Denver,
Colo, area. Thin-layer chromatography (TLC) was used to determine species
and measure quantity. From this information, accuracy of species labeling
and comparison of constituent to labeled content were assessed. The
samples were stratified by whether they were labeled as standardized, and
the standardized and nonstandardized samples were compared by ratio of
constituent to labeled content.
Results: Of the samples, 6 (10%) of 59 preparations contained no
measurable Echinacea. The assayed species content was consistent with
labeled content in 31 (52%) of the samples. Of the 21 standardized
preparations, 9 (43%) met the quality standard described on the label.
Labeled milligrams were weakly associated with measured constituent (r =0.35; P = .02).
Conclusions: Echinacea from retail stores often does not contain the labeled species. A claim of "standardization" does not mean the
preparation is accurately labeled, nor does it indicate less variability in concentration of constituents of the herb.