Consider researching Astragalus a bit more and make sure your pills are from a trusted source. The FDA does not regulate supplements, so the level of selenium and other included metals can vary widely. Astragalus plants grow in high-selenium soils, which also tend to be high-uranium soils. I was a uranium exploration geologist almost 50 years ago and we would sample and analyze Astragalus leaves as a marker for uranium because they concentrate under similar geochemical conditions. https://www.nccih.nih.gov/health/astragalus