The variability of the phytochemical content of Echinacea products was highlighted by a survey of Echinacea products on the German market, which found wide variations in levels of tested phytochemical components (Osowski et al., 2000). The authors chose to use chicoric acid and the two main alkamides in E. purpurea as quality markers, since these have been described as immu-nomodulating active components in this species. The same alkamides are also found in E. angus-tifolia. In regard to these quality markers, the authors found highly concentrated products as well as those without any detectable chicoric acid or alkamides. The concentration of both marker compounds varied markedly depending on how the product was manufactured (homeopathic mother tincture, pressed juice, tablets, spagyric tincture) and the species and plant part used. Even more disturbingly, large differences in quality were found among different batches of the same product. Osowski et al. (2000) recommended that any pharmacological or clinical studies with Echinacea products should always include quantification of the potentially active components.
Not long after this publication, ConsumerLab.com, an independent evaluator of dietary supplements, released the results of its product review of Echinacea products (ConsumerLab.com, 2001). Eleven of 25 Echinacea products available on the U.S. market (i.e., 44 per cent) did not pass the criteria set by ConsumerLab.com for its quality review. Six products did not provide sufficient label information to identify the amount and form of Echinacea used or the species or plant part used (a Food and Drug Administration requirement), and were dropped from further testing. Four products had insufficient levels of marker compounds and one product exceeded the World Health Organization limit for microbial contamination.
The results of these two surveys are supported by similar results from a quality evaluation of E. purpurea products on the Australian market (Wills and Stuart, 1998). All three studies support what many phytotherapists have maintained for some time: the efficacy of Echinacea products varies tremendously due to the quality of raw material, the plant part and plant species used, and the manufacturing process. This variability makes it difficult to provide a meaningful assessment of the current pharmacological and clinical data for Echinacea (Melchart and Linde, 1999).
Recent studies have provided some insight into the observed variability in marker compounds in Echinacea products. Apart from variation due to plant part (the roots of E. purpurea contain higher levels of alkamides and lower levels of chicoric acid compared to the leaves), different methods of drying can dramatically alter the profile of marker compounds (Kim et al., 2000a, 2000b). Using a fresh plant extract is not the answer because enzymatic degradation will destroy the chicoric acid and the highly lipophilic alkamides will not be effectively extracted (Nusslein et al., 2000).
Regarding the two recent surveys, the levels of alkamides found in the German products (either leaf or root) were nowhere near the levels found in high-quality root extracts. The highest alkylamide level was 0.06 mg/ml whereas a good-quality 1:2 extract of E. purpurea root could contain more than 10 times this level (Lehmann, 2002). The ConsumerLab.com study unfortunately did not use alkamides in its quality assessment and it would have been interesting to see how many products passed under that (more stringent) assessment.
limitations on the use of ECHINACEA
As outlined at the beginning of this chapter, monographs on Echinacea and anecdotal accounts often refer to limitations on its use. In particular, there is referral to the concept that Echinacea will cause a tachyphylaxis in immune response and hence should only be used for 5 days or so. Certainly continuous use is not advised by several sources. Also it is often written that Echinacea is contraindicated in autoimmune disease. The origin of this highly cautious approach to what is a relatively benign agent needs to be critically examined.
The concept of traditional use is very misunderstood. For example, conventional medical scientists often confuse traditional use information with that from folk use or anecdotal accounts. It is important that the concept of traditional use is elevated to the high status it deserves.
In the case of Echinacea, information about its use first came from Native American tribes. Their use of Echinacea was then adopted by the Eclectics, a group of practitioners who were prominent around the late 19th and early 20th centuries in the U.S. By 1921, Echinacea (specifically the root of E. angustifolia) was by far the most popular treatment prescribed by Eclectic physicians (Wagner, 1996). The Eclectics used Echinacea for about 50 years, which is a relatively short period in the context of traditional use. However, given that the Eclectic use of Echinacea was based on tribal knowledge and that they accumulated extensive clinical experience in its use, their traditional use data is of a relatively high quality. The best sources of these data are King's American Dispensatory (Felter and Lloyd, 1993) and Ellingwood (1993).
The extensive range of conditions for which the Eclectics prescribed Echinacea is summarized in Table 14.1. It is clear from this table that the limitations on Echinacea suggested by modern writers are not supported. The conditions in the table are mainly infections and envenomations of various kinds (which clearly attest to Echinacea's influence on the immune system). However, the inclusion of tuberculosis and disorders related to autoimmunity such as diabetes, exophthalmic goiter, psoriasis, and renal hemorrhage contrasts with the contraindications suggested by some modern writers.
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