Astragalus

Various Astragalus species are used in alternative medicine around the world.^[1][2] This page refers to Astragalus membranaceus, a popular herb used in traditional Chinese medicine, also known as Astragali radix or huangqi.^[3][4] Astragalus membranaceus can be used alone, but it is also paired with another herb called Angelicae sinensis in Danggui Buxue Tang, a Chinese medicine.^[5] Astragalus membranaceus contains several bioactive compounds, including polysaccharides, flavonoids, and saponins. One of its major bioactive molecules is called astragaloside IV.^[6][7], and another of its bioactive extracts has been patented under the name TA-65 (telomerase activator 65).^[8]

There are widespread claims about the beneficial effects of Astragalus membranaceus and its extracts (e.g., astragaloside IV, TA-65, etc.) on several conditions. These include chronic heart failure,^[9][10] metabolic syndrome,^[11] blood lipids,^[12] diabetes,^{[13][14][15][16]} kidney disease,^{[17][18][19][20][15][16]} neurological disorders,^[21] cell lifespan,^[3][8] and cancer.^{[22][23][24][25]} However, the quality of evidence for these effects in humans is generally low because of variable findings between studies, poor methodological quality, unclear methodological details, widespread lack of blinding, use of intravenous rather than oral administration, and publication bias in favor of predominantly positive findings being published.^{[9][10][17][18][19][20][12][13][14][22][23][24][25]} Furthermore, much of the evidence supporting the benefits of astragaloside IV is derived from animal and cell culture experiments,^{[26][15][16][27][21][28]} while clinical studies showing the therapeutic benefit of TA-65 are authored by the group that patented the compound.^[8][11] Consequently, high-quality randomized controlled clinical trials by independent researchers are urgently needed to confirm these therapeutic claims.

There is no obvious toxicity nor serious side effects caused by Astragalus membranaceus or its extracts.^{[29][30][31][32][8][9][10]} However, human studies often fail to record the side effects of astragalus.^{[17][33][32][9][10][20]}

The main drawback is that research in this field has major limitations. For example, systematic reviews conclude that evidence in this field is generally of low quality.^{[9][10][17][18][19][20][12][13][14][22][23][24][25]} Furthermore, it is often unclear which species (e.g., Astragalus membranaceus) or part (entire plant, roots, flowers, etc.) of an Astragalus plant is used, or which type of extract is administered (i.e., a total or purified extract). Additionally, astragalus extracts are often combined with other compounds or drugs so their direct effects cannot always be determined. These limitations reduce the certainty of the claimed benefits.

Pharmacological research indicates that Astragalus membranaceus^{[3][34][35][36]} and its extracts (e.g., astragaloside IV^{[37][38][6][7]} and TA-65^{[39][40][37][8]}) can regulate several pathways, including antioxidant, anti-inflammatory, and immunological systems, as well as increase telomerase activity, which prolongs the lifespan of cells. This may explain the potential role of astragalus in the treatment of chronic disease. However, most pharmacological evidence is derived from cell culture (i.e., in vitro) and animal experiments.^{[26][15][16][27][21][28]} Further clinical pharmacology research is needed to fully understand the potential mechanism(s) of action in humans.