Astragalus

This post was motivated by a patient who chose to take astragalus supplements instead of receiving steroid-based medication to treat a flare up of their inflammatory bowel disease. Whatever treatment you choose, the choice is yours in the end. But you deserve to have all the information you need to make an educated decision.
Since I hadn't heard much about this supplement, I decided to conduct a bit of research to assess the scientific evidence behind the use of this product.
Astragalus can be found as a supplement from the plant Astragalus membranaceus. It has been used in traditional Chinese medicine for immune system support; In China it has been used for chronic hepatitis, colds, upper respiratory tract infections, cancer therapy, and heart disease. The root of plant is often used in soups, teas, extracts, or capsules.

The National Center for Complementary and Alternative medicine suggests that the evidence to support health claims for this product is lacking. They also state that the supplement is safe for most adults, but certain species that are not usually in supplement, can be toxic. There is a possibility that astragalus may interact with medications that suppress the immune system and may affect blood sugar and blood pressure.

Some studies (not on humans) have found astragalus to inhibit human gastric cancer cell growth in lab. Another study on humans suggested it could have potential in treatment of cancer-related fatigue. While a 2011 study of 90 participants suggested that daily astragalus + perindopril improved heart contraction. However, this study did not include a control group which was not receiving astragalus (to compare results to). In addition, it is not clear if positive results obtained could also be related to the medication perindopril (medication used to manage blood pressure and promote blood to flow more smoothly).

The American Cancer Society suggests that "the ability of astragalus to enhance the immune system and fight diseases, including cancer and heart disease, comes mostly from lab and animal studies."
It is important to understand that it cannot be assumed that effects seen in a test tube in a lab or in animals would be the same as in humans. The Cancer Society concludes that "available scientific evidence does not support claims that astragalus can prevent or cure cancer in humans or decrease the toxic effects of chemotherapy or other cancer treatments." More experiments in humans are needed to determine if there are benefits to the use of astralagus.

If you're still interested in using astragalus, speak with your physician and pharmacist first to ensure its safety. Doses found to be safe by Health Canada can be found on their 2010 Astragalus Monograph.

Information Sources:
http://nccam.nih.gov/health/astragalus
http://www.cancer.org/treatment/treatmentsandsideeffects/complementaryandalternativemedicine/herbsvitaminsandminerals/astragalus
http://webprod.hc-sc.gc.ca/nhpid-bdipsn/monoReq.do?id=36&lang=eng
http://www.ncbi.nlm.nih.gov/pubmed/24152941
http://www.ncbi.nlm.nih.gov/pubmed/22309959
http://www.ncbi.nlm.nih.gov/pubmed/21390582
http://www.nlm.nih.gov/medlineplus/druginfo/meds/a602017.html