Effective Use of Mild Acting Herbs I. Huang Qi (Astragalus)
Huang Qi (Astragalus root) is a commonly used Chinese herb in the Fabaceae Family (legumes). Some practitioners may think of it as a "strong" qi tonic. Yang Yifan, in her text 'Comparisons and Characteristics of Chinese Herbs', places astragalus well below ginseng but slightly above codonopsis (Dang Shen) in terms of its "strength" as a qi tonic (Yang 2002). Nonetheless, astragalus fits well with the concept of being among the very mild herbs of Chinese medicine. For those who have used the root slices in tea making, are aware they are quite fibrous and release only a small amount of material into the tea. Its taste is mild and sweet.
Mild acting herbs have these qualities: low toxicity; low incidence of adverse reactions at normal dosage; and the normal dosage are relatively high. As a contrast to mild acting herbs, there are those that have notable toxicity (such as raw aconite/Fu Zi), those that easily cause adverse reactions (such as rhubarb/Da Huang causing intestinal cramping or loose stool), and those that have significant effects at low dosage (e.g., the warming effect of zanthoxylum at just a gram per day).
To better understand the mild acting herbs, it is helpful to look at their active ingredients in terms of their quantities and effects, and this can be accomplished with astragalus, which is relatively well studied.
After several decades of study, there are three groups of active constituents that have become known for astragalus: flavonoids (which give the yellow colour to the root slice), saponins (a common ingredient of plants in this family), and polysaccharides (long-chain polysaccharides with potential medicinal benefit). The quantities of these components will vary somewhat depending upon the species of Astragalus used, the growing conditions, and other factors. Of course, there are many other components of astragalus root, but they are either ordinary components found in foods (such as carbohydrates and proteins) or potentially active ingredients that are present in such small amounts as to not contribute significantly to the effect of whole herb preparations.
Flavonoids are found in all higher plants, but some plants are rich sources of them; thus, for example, another member of the Fabaceae family commonly used in Chinese medicine, pueraria root (Ge Gen), has flavonoids as the primary active ingredient (aside from its starches that are soothing to the gastro-intestinal system). There are numerous potential beneficial effects of flavonoids (Dharmananda 1997), but when present in modest amounts, as is the case with astragalus, the primary effect is to benefit circulation. Other actions, that are noted for high doses of flavonoids, such as anti-allergy and anti-viral activity at over 1 gram per day (of the flavonoids themselves), would not be expected from most astragalus extracts. In one recent study it was noted that "In the roots, isoflavonoid content was extremely variable, but reached 3.04 mg/gram, whereas flavonol content was 0.49 mg/gram. Modern supplements that provide flavonoids for therapeutic benefit have several hundred milligrams making up a one day dose". The isoflavonoid and flavonol content mentioned here (using the figure given for the maximum) is 3.5 mg/gram (0.35%), so that a 15 gram daily dose of astragalus would yield only about 50 mg of these flavonoids, a small amount. The isoflavones of soy, reputed to help with menopausal symptoms, are effective at doses of 60-180 mg or more per day. In some industry extracts, standardization is for the product at just 0.5% of the main isoflavone.
The saponins of astragalus include those called astragalosides (-oside indicates that it is a glycoside, that is, has a sugar attached to an active molecule, such as a pentacyclic compound in saponins). In a study of astragalus roots from China, the saponin content was found to be from 0.019 to 0.184%, with astragaloside I as the main component (Agrifood Innovation Fund 2001). When astragalus extracts are made and standardized for saponin content, a 5% content is the most that is usually attained. In a previous analysis of saponin-containing herbs, I showed that a likely range of substantial activity for these compounds would be attained with about 60-900 mg (Dharmananda 2000). A 15 gram daily dose of astragalus might yield as much as 28 mg total saponins, a small amount. These saponins of astragalus, if given in sufficient quantity, may have properties such as reducing inflammation, resolving phlegm, reducing platelet sticking, and promoting cardiac function.
The polysaccharides of astragalus may be present in relatively large quantity, though the amount extracted is not known (polysaccharides are not soluble in alcohol, so are not present in tinctures or other alcoholic preparations; they are soluble in water, but the desired high molecular weight ingredients may be only partially extracted from the herb under normal conditions). It is relatively easy to isolate polysaccharides by first using hot water extraction and then condensing them out of solution with alcohol. Commercial extracts have been standardised to 40-50% polysaccharides, and one source claims 70% polysaccharides (but the accuracy of this is suspect). These levels are as high as attained with mushrooms that are used specifically for their polysaccharides (typically 40% polysaccharides in standardised extracts). A reasonable estimate for the content of the dried roots is about 10% extractable medicinally active polysaccharides (in one commercial extract, the concentrated material has just 16% polysaccharide and 0.2% flavones). In a previous analysis of medicinally active polysaccharides and their applications, I showed that a daily dosage of 3.0-3.5 grams of these polysaccharides would be reasonable to attain some level of activity (Dharmananda 1999). A 30 gram dose of astragalus would have about this amount of polysaccharides. The polysaccharides have the reputation of enhancing immune functions and specifically in improving white blood cell responses. Polysaccharides have been used, especially, in attempts to overcome the immune debilitating effect of radiation and chemotherapy as used in cancer treatments. In China, astragalus is most often used in doses of 15-30 grams per day in decoction for this application.
The analysis of active constituents reveals that a dose of about 15 grams of astragalus, as frequently used in decoctions, may be sufficient to attain only some of the desired effects of the known active components, and that a 30 gram dose would be more suitable.
The Materia Medica recommendations for astragalus dosing are 9-15 grams/day (understood to be used in formulas with other herbs), with high doses of 30-60 grams also suggested, at least for some applications (usually not specified). When dosing below 15 grams, an herbalist is counting on other herbs in a formula to contribute some similar active components in order to get the desired therapeutic action. Thus, for example, a decoction made with astragalus, ganoderma (Ling Zhi), and red ginseng (Ren Shen) would have polysaccharides and saponins from all three herbs, and so long as the total dosing of these three ingredients was sufficient, then astragalus at 9-15 grams/day would be acceptable.
Lower doses of astragalus would not be entirely ineffective, but the action would be limited. As an example, the polysaccharides can have benefits for the stomach (e.g., alleviating ulcers) at doses below that necessary to cause the immunological effects, because of the direct action of the full amount of the herb ingredients on the stomach before being distributed throughout the body. Thus, pills with a little astragalus included will have this type of action from astragalus. Following absorption, the astragalus ingredients are diluted into a large volume of blood and some begin to be metabolised and eliminated after just a few minutes.
The recommended high doses of astragalus, at 30-60 grams per day, are typically used in short-term therapies to get a stronger action, and this dosage should yield a substantial effect from both the saponins and polysaccharides, with some effect also from flavonoids. It is not known if prolonged use of these higher dosages could be detrimental, but a reasonable caution would be to limit the duration to a few days at a time when needed, rather than a continuous therapy.
Let us examine a few of the traditional indications. In the text 'Chinese-English Manual of Commonly Used Herbs in Traditional Chinese Medicine' five major uses are given, as well as some miscellaneous new uses (Ou Ming 1989):
1. Invigorate qi and spleen (poor appetite, loose stools, fatigue, and bleeding).
2. Invigorate qi to activate yang (prolapse of stomach, uterus, or rectum)
3. Invigorate qi to strengthen the body (common cold in debilitated patients, profuse sweating due to weakness)
4. Relieve skin infection and promote tissue regeneration (abscesses, skin erosion, unhealthy wound); also for erosion of stomach lining (ulcer, atrophic gastritis)
5. Promote diuresis and relieve oedema (spleen-deficiency type oedema).
6. Miscellaneous new uses: diabetes, hemiplegia, asthma, and leukocytopenia (low white blood cells); all of these in cases of qi deficiency or qi and yang deficiency.
It is important to distinguish between traditional indications (some of which are based solely on dogma and not on careful observation) and known effective actions (which might be confirmed through clinical trials). For example, it would be a mistake to think that a prolapsed organ would go back into place merely by taking some astragalus or by using this herb in a qi tonic formula. This indication for astragalus comes from three considerations:
a) A prolapse indicates muscular weakness; the muscles are ruled by the spleen qi, becoming weaker with reduced qi; astragalus is a spleen qi tonic.
b) A prolapse represents a falling of an organ from its place; the upward flow of qi is promoted by herbs that invigorate qi and yang, hence astragalus is appropriate in that its "direction" of action is upward against the fall of the organ.
c) Since a prolapse often produces a heavy sensation and fullness or swelling where the organ has moved, the syndrome is like one of moisture accumulation; herbs that remove dampness, such as astragalus, may be of help.
These theoretical reasons for using astragalus are consistent with Chinese medical theory, but there is no evidence to show that the appropriateness of astragalus in this instance corresponds to its effectiveness. Indeed, in order to reverse prolapse non-surgically, one often needs to strengthen the muscles surrounding the organ, which requires doing physical exercise. If taking herbs will, by whatever mechanism, improve one's sense of energy and capability, then the person might undertake more exercise and that activity would, in turn, control or reverse the prolapse. That is how such a formula might actually work. If the herbs do not aid one in pursuing the physical activity, they are unlikely to have any substantial impact on the prolapse.
While an analysis of each of the claimed activities for astragalus is beyond the scope of this article, it can be said that those which directly affect digestion, such as treating low appetite, loose stool, stomach ulcer, and atrophic gastritis, may be partly explained by direct action of the ingredients on the lining of the stomach and intestine. Saponins and polysaccharides are likely to be the main active components, potentially of benefit in small doses. Resolving skin infections and erosion, aiding treatment of common cold, and promoting while blood cell function are actions that would require the higher dosages discussed above. Claimed diuretic effect of herbs is an area of some difficulty to interpret, as the drinking of decoctions is, in itself, a potential means of diuresis because of the fluid consumed. Further, the body’s elimination of the chemical constituents of the herbs and their metabolites is primarily by diuresis, a process which may be stimulated by high levels of such chemical compounds. Low dosage pills are unlikely to have much diuretic effect, both because of the low dose and because of the lower fluid intake (unless they are swallowed down with a large amount of water or tea).
To conclude, astragalus can be an effective agent, though one must give due considerations to its preparation and dosage according to the application, and one must be careful how indications that appear in the traditional literature are interpreted.
Agrifood Innovation Fund. Medicinal Herb Production in Northeast Saskatchewan. Available from: http://www.agr.gov.sk.ca/afif/Projects/19970402.pdf (Accessed April 2006).
Dharmananda, S. (1997). Flavonoids and Health, Portland, Oregon, Institute for Traditional Medicine.
Dharmananda, S. (1999). the Physiological Responses to Immunologically-Active Polysaccharides, Portland, Oregon, Institute for Traditional Medicine.
Dharmananda, S. (2000). Platycodon and Other Chinese Herbs with Triterpene Glycosides, Portland, Oregon, Institute for Traditional Medicine.
Ou, M. (1989). Chinese-English Manual of Commonly Used Herbs in Traditional Chinese Medicine. Hong Kong: Joint Publishing Company.
Yang, Y. (2002). Chinese Herbal Medicines: Comparisons and Characteristics. London: Churchill-Livingstone.