In early writings from traditional Chinese medicine, astragalus is frequently discussed for its use in a multitude of ailments.1 The genus astragalus describes a large family of herbs and small shrub-like plants. Common names for the plants include milk vetch and locoweed.2 The species most commonly used medicinally is Astragalus membranaceus.1 Major areas of research on the potential health benefits of A. membranaceus are oncology and congestive heart failure.
Background
Astragalus is a perennial plant that is native to northern and eastern regions of China, Mongolia, and Korea; the root is the medicinal part of the plant.1 In traditional Chinese medicine, astragalus was often used with other herbs to strengthen the body against disease.1
Astragalus is referred to as an adaptogen, a term that indicates the value of the plant in protecting the body against physical and mental stress.1 A large variety of beneficial properties have been suggested for astragalus. These include antioxidant, antibacterial, anti-inflammatory, and antiviral properties.1
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There are many studies examining both the efficacy and safety of the use of A. membranaceus. However, there is a paucity of data from well-designed, randomized, controlled trials. For oncology and congestive heart failure, however, mechanisms of action have been proposed and fairly well-established for A. membranaceus.
Science
Perhaps the most exciting research involves the use of A. membranaceus in the treatment of cancer. A. membranaceus has antitumorigenic activity.3
In a laboratory study conducted on a human colon cancer cell line, an herbal compound containing astragalus cells inhibited cell growth, promoted apoptosis, and induced ‘phase-specific’ cell cycle arrest. The colon cancer cells were treated with either a known anti-tumor compound or an extraction of an herbal compound containing astragalus. Both compounds inhibited cell growth and promoted apoptosis, but only the herbal compound induced phase-specific cell cycle arrest.3 Further research into this phenomenon strongly suggests that A. membranaceus interrupts cell growth by increasing the production of the enzyme telomerase, which disrupts the normal DNA replication process.4
In spite of the lack of good trials, the centuries of use of astragalus in traditional Chinese medicine for congestive heart failure bears mention. While the exact mechanism of action is not known, it is believed that astragalus enhances myocardial contractility and promotes vasodilation.5
A small study found that astragalus induced urinary sodium excretion by enhancing the renal response to endogenous atrial natriuretic peptide (ANP).6 ANP is a cardiac hormone that helps regulate the body’s water and salt homeostasis. By this action, ANP helps protect the body against fluid overload by decreasing intravascular fluid volume. In a well-executed feedback loop, this fluid reduction then results in diminished cardiac secretion of ANP.7 The double-blind, randomized, crossover clinical trial included 12 healthy males. The results indicated that a single, weight-based oral dose of astragalus supplement induced urinary sodium excretion by promoting renal response to endogenous ANP. This occurred without a change in the renin-angiotensin-aldosterone system, but actual serum levels of ANP were increased in the treatment subjects.6
