Used for thousands of years in Chinese medicine, Astragalus membranaceus has only recently gained popularity in America in the past few decades. There are over 2,000 species of Astragalus worldwide, but Astragalus membranaceus and Astragalus mongholicus constitute the majority of herbal supplements seen in health food stores today.
The uses of Astragalus are myriad and continuing to grow. Astragalus may be taken by itself, or in formula with other medicinal herbs. For example, Astragalus and Angelica in formula may act synergistically to produce renal protective effects [PMID: 12123567]. When taken at the recommended dose (25 g per day), Astragalus has also shown promising results in patients with cancer, both in increasing immune system activity, as well as decreasing the side effects of chemotherapy.[i]
Astragalus is not only an immune booster, but also an “adaptogen.” Adaptogens help protect the body from the inflammatory effects of physical, mental, and emotional stress. In being an anti-inflammatory agent, Astragalus has even been shown to alleviate airway hyperactivity due to allergic asthma in children [PMID: 21910341]. Furthermore, as if the previously mentioned benefits were not astounding enough, Astragalus has also been shown to reduce fatigue in athletes by elevating oxygen uptake and enhancing its utilization.[ii]
Although there are likely numerous mechanisms that have yet to be elucidated through scientific testing, it has been shown that some of this herb’s activity stems from bolstering immune cell function. Polysaccharides and saponins in Astragalus have been shown to increase the activity of lymphocytes, enhance natural killer cell efficiency, positively modulate the activity of monocytes, and potentiate phagocytosis [PMID: 24152941]. Because Astragalus reinforces the immune system with such intensity, it is often administered to individuals undergoing chemotherapy and radiation, treatments that often leave patients immunocompromised.
Consumed as herbal tinctures, extracts, supplements, teas, and in soups, Astragalus is versatile in its methods of administration. Other species of Astragalus, (e.g., Locoweeds found in the United States) are not recommended and may have unknown side effects; some are clearly toxic to animals. It is best to stick with either Astragalus membranaceus or Astragalus mongholicus. Consultations with experienced herbalists and naturopathic physicians are also recommended before taking Astragalus, due to its potency and possible interactions with certain medications.
Possible Interactions and Contraindications
Astragalus should not be taken during pregnancy and/or lactation. With cardiac insufficiencies or abnormalities, use only on a health professional’s advice. Unless advised by an experienced herbalist or health professional, Astragalus should not be taken longer than 8 weeks without a 2-3 week break.
Astragalus may interfere with immunosuppressant drugs. If you have an autoimmune disease, such as a rheumatoid arthritis or lupus, use Astragalus with caution. Astragalus may also interfere with drugs used to prevent organ transplant rejection; thus it may be best to avoid Astragalus in these cases as well. Astragalus may also slow the liver’s processing of the drug lithium, leading to toxic buildup.