RecruitingDietary supplementLong-term COVID and RehabilitationThe proposed focuses on improving both morbidity and mortality in older Veterans and those recovering from COVID-19 by developing rehabilitation therapies to augment vascular endothelial function by combating the oxidative stress and inflammation associated with aging and further induced by COVID-19. The investigators expected outcomes will have an important positive impact because they will provide scientifically sound recommendations for rehabilitation to improve vascular endothelial function and minimize the long-term consequences of COVID-19.