Volunteers are needed for a human biology study focusing on Echinacea and the immune system. Echinacea is a popular supplement used to reduce the severity and/or duration of respiratory infections, including the common cold. Despite its popularity, the effects of Echinacea on the immune system remain poorly understood. Volunteers in this study will take either Echinacea or placebo-control capsules three-times daily for seven days. Pre-treatment and post-treatment health surveys and blood samples (4-6 teaspoons) are required. There is no monetary compensation for study participation and your identity will remain confidential. Volunteers may discontinue participation at any time. All are welcome to participate, including prior participants. Please contact Associate Prof. Brian Merkel (Human Biology) via email at firstname.lastname@example.org with any questions.