Astragalus root, native to Asia, has long been used medicinally in capsules, ointments, injectables, soups and teas. Late last year, researchers at the University of California in Los Angeles announced some test-tube study results: Adding an astragalus extract to immune cells of HIV-positive people helped the cells fight the virus. The secret? A chemical in the root slows immune-cell aging—a process otherwise hastened by HIV. Before you start the kettle, listen to study author Rita Effros, PhD: “Further work needs to be done, in animals and then human safety studies, before we can conclude that astragalus is ready for prime time.” Nonetheless, some positive people already stock it in their arsenal of supplements.