Astragalus

Astragalus is a famous adaptogen from traditional Chinese medicine that has been used for thousands of years to promote health and longevity.  It is classically known to support the immune system, digestive system, respiration, and other core components of our physiology.  Modern studies have found that astragalus is beneficial in chemotherapy.

Astragalus enhances efficacy and reduces toxicity of chemotherapy:
http://europepmc.org/abstract/med/12592686

Astragalus improves immune function in mice:
http://www.sciencedirect.com/science/article/pii/016231099090038G

Anti-aging effects of astragalus:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3291990/