Astragalus is also called huang qi or milk vetch. It comes from a type of bean or legume. While there are multiple species of astragalus, most astragalus supplements contain Astragalus membranaceus. The herb is said to offer multiple health benefits for multiple conditions, including heart benefits.
Astragalus appears to work by stimulating the immune system. It has antioxidant effects that inhibit free radical production. In the body, free radicals damage cells and are linked to many health problems associated with aging. There is, though, no known way to stop free radicals completely.