Astragalus is a large genus of over 3,000 species[2] of herbs and small shrubs, belonging to the legume family Fabaceae and the subfamily Faboideae. It is the largest genus of plants in terms of described species.[3] The genus is native to temperate regions of the Northern Hemisphere. Common names include milkvetch (most species), locoweed (in North America, some species)[4] and goat's-thorn (A. gummifer, A. tragacantha). Some pale-flowered vetches (Vicia spp.) are similar in appearance, but they are more vine-like than Astragalus.
Traditional medicine
Astragalus has been used in traditional Chinese medicine over centuries to treat various disorders, but there is no high-quality evidence that it is effective or safe for any medical purpose.[11][12]
Phytochemicals and supplements
Extracts of astragalus root include diverse phytochemicals, such as saponins and isoflavone flavonoids, which are purported in traditional practices to increase lactation in nursing mothers.[13] There is no valid clinical evidence to indicate such use is effective or safe for the mother or infant.[13] Dietary supplement products containing astragalus extracts may not have been adequately tested for efficacy, safety, purity or consistency.[13] The root extracts of astragalus may be used in soups, teas or sold in capsules.[11]
Side effects and toxicology
Although astragalus supplements are generally well tolerated, mild gastrointestinal upset, diarrhea, and allergic reactions may occur.[11][13] Because astragalus may affect regulation of blood sugar and blood pressure, it may be risky for people with blood disorders, diabetes, or hypertension to use it as a supplement.[11] Astragalus may interact with prescribed drugs that suppress the immune system, such as medications used by people being treated for cancer or recovery from organ transplants.[11]
Some astragalus species can be toxic, such as those found in the United States containing the neurotoxin swainsonine, which causes "locoweed" poisoning in animals.[11] Some astragalus species may contain high levels of selenium, possibly causing toxicity.[11]