Astragalus is a traditional Chinese herb derived from the root of the perennial Astragalus membranaceus. In China astragalus enjoyed a long history of use in traditional medicine to strengthen the Wei Ch'i or "defensive energy" or as we call it, the immune system. Regarded as a potent tonic for increasing energy levels and stimulating the immune system, astragalus has also been employed effectively as a diuretic, a vasodilator and as a treatment for respiratory infections.