Native to Mediterranean areas and the Middle East, celery (Apium graveolens) is a member of the carrot family and has been cultivated for thousands of years. Historically, celery has been used as a flavoring agent and for medicinal purposes, and was even used as an award for sporting events in ancient Greece. It wasn't until the 1600s that celery was actually used alone for food.

Research is showing that the early use of celery as a medicine was not unfounded. 3-n-butyl phthalide, one of the components that gives celery its characteristic smell and taste, is especially potent as an anti-tumor agent. Along with the compound sedanolide, an aromatic ingredient also found in celery, 3-n-butyl phthalide significantly reduces the incidence of tumors in laboratory animals. Other studies suggest that this and other phthalides may also help reduce high cholesterol.

Even though it's high in sodium (as vegetables go), celery is also proving to be effective at lowering blood pressure because 3-n-butyl phthalide has been demonstrated to relax the smooth muscles that line blood vessels.