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Friday, October 12, 2007

More on Astragalus

Note: The following appeared in issue # 23 of Dr. Leung's newsletter, originally published in 1999.

Astragalus is the root of Astragalus membranaceus and A. mongholicus as well as other Astragalus species. Despite specific labeling, few astragalus products sold on this continent or elsewhere can be traced to the particular species labeled. Which is not new, as TCM uses the roots of these Astragalus species interchangeably. This makes labeling anything more precise than the plant genus of little practical value and is used basically to appease the "scientific" minded or federal regulators who are accustomed to dealing with single-chemical drugs. To them, even a well-defined plant species is already a little difficult to accept, let alone a genus that may include one of several species. Hence those involved in writing specifications or monographs of Chinese herbs either are of the same mentality or simply adopt it to make things easier for all, even though they are well aware of the impracticability of specifying a particular plant source in many commercial products. On the contrary, herb labeling in commercial products has been quite different in China. For example, astragalus in China is simply labeled as huang qi in Chinese, sometimes accompanied by its Latin pharmaceutical name, radix astragali, which we all understand to be the root from 1 of at least 2 related plants. However, things are changing. In order to comply with US regulations, some Chinese manufacturers and suppliers are starting to label herbs with Latin binomials. While this is great for simplistic justification and documentation purposes, it is often inaccurate or at best, misleading, as in the case with astragalus. The fact is this. In commerce, there is no way to tell the source of astragalus in a product, no matter how it is labeled. One can only be reasonably sure that it is either from A. membranaceus or A. mongholicus.

I have written about astragalus in most previous issues of this Newsletter as well as in my books. The beneficial biological activities of astragalus (as powdered herb, decoction, and various extractives) have been well documented. They include the following activities: immunostimulant, antiviral, antioxidant, cardiovascular, memory improving, antifatigue, etc. However, when we make these statements, we frequently forget to clarify and specify what form(s) of astragalus exhibits these activities. Is it the decoction, the powdered root or some highly purified chemical fraction (e.g., saponins, polysaccharides) [See issue 19, pp. 2-3 for criteria for evaluating herb research]? We often use "astragalus" as if it were a well-defined chemical entity, but in fact, it is not. When I see the word "astragalus" without any qualifier, I would take it, though without certainty, to mean huang qi (astragalus root) normally used as a powder, decoction, or total alcoholic extract. It definitely should not be used to describe a specific "injectable liquid" or a saponin or flavonoid fraction. Yet this is often the case, even in so-called "professional reviews" intended for health practitioners.

I have just read such a "Professional Review" on astragalus by MediHerb (#67, February, 1999), published in Australia. The word "astragalus" without qualifier was used more than 2 dozen times in this 4-page review. A few of these, when used in the traditional context, seem clear enough. However, when I looked up a few of the original references quoted, I discovered that many instances of the "astragalus" used were for describing modern findings. Some of them represented undisclosed proprietary preparations (including combinations) and modern "injectables" or "oral liquids" containing astragalus. It appears that the authors might have based their information primarily on abstracts from the National Library of Medicine. The reason is that, as far as I know, only the Library of Congress, the NLM and Taiwanese institutions still use the archaic Wade-Giles transliteration system, which predominates in the literature cited in this review. Hence, it is highly possible that the authors never saw the original references and would not know what was actually being used in the studies reported. They had two strikes against them: (1) Chances are that the original reports never clearly identified the nature of the herbs used in the study; and (2) Even if the herbal materials used in the studies were clearly identified in the reports, chances are that NLM abstractors, who are not trained in the intricacies of natural products, did not recognize the importance of specificity and failed to carry it over into the abstracts. The result is that more useless or ambiguous information is generated, cluttering the NLM database, which is spread like a virus to other databases and print media.

This and more herbal information is available from the volumes of Dr. Leung’s newsletter, of the same name as this blog (Leung’s Chinese Herb News). This newsletter was published and sent to subscribers (most were industry-insiders) from 1996 to 2004. The collected works now serve as an excellent reference work, created with Dr. Leung’s frank, honest opinions and down-to-earth communication style.

For more information about Dr. Leung and his writings, visit www.earthpower.com. To order the newsletter referenced above, visit the bookstore, click “Buy Now” on the newsletter, and select Issue # 23 from the drop down list.

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