Parsley can provide much more than a decoration on your plate. Parsley is listed as one of the top ten lycopene-dense foods. In addition to its volatile oils and flavonoids, parsley is an excellent source of two vital nutrients that are also important for the prevention of many diseases: vitamin C and vitamin A (notably through its concentration of the pro-vitamin A carotenoid, beta-carotene).

Free radicals can damage cells, and may play a role in heart disease, cancer and other diseases. Scientists have linked destructive oxygen reactions to ailments, such as cancer, Arteriosclerosis, atherosclerosis, heart disease, cerebrovascular disease, stroke, emphysema, diabetes mellitus, rheumatoid arthritis, osteoporosis, ulcers, sunburn, cataracts, Crohn's disease, Behcet's disease, aging, senility.

Parsley contains two types of unusual components that provide unique health benefits. The first type is volatile oil components including myristicin, limonene, eugenol, and alpha-thujene. The second type is flavonoids including apiin, apigenin, crisoeriol, and luteolin. Parsley's volatile oils, particularly myristicin, have been shown to inhibit tumor formation in animal studies, and particularly, tumor formation in the lungs. Myristicin has also been shown to activate the enzyme glutathione-S-transferase, which helps attach the molecule glutathione to oxidized molecules that would otherwise do damage in the body.

The activity of parsley's volatile oils qualifies it as a "chemoprotective" food, and in particular, a food that can help neutralize particular types of carcinogens (like the benzopyrenes that are part of cigarette smoke and charcoal grill smoke). The flavonoids in parsley, especially luteolin, have been shown to function as antioxidants that combine with highly reactive oxygen-containing molecules (called oxygen radicals) and help prevent oxygen-based damage to cells.

In addition, extracts from parsley have been used in animal studies to help increase the antioxidant capacity of the blood. One of its most critical roles in relation to cardiovascular health is its necessary participation in the process through which the body converts homocysteine into benign molecules.