Archives of Internal Medicine, vol. 163, issue 6 (2003) pp. 699-704
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.
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