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. Astragalus has been used in traditional Chinese medicine over the centuries to treat various disorders. Its main use has been to boost the body's immune system. But it also has been used to treat other conditions, including heart disease.