Kale is a form of cabbage, green or purple, in which the central leaves do not form a head. It is considered to be closer to wild cabbage than most domesticated forms. The species Brassica oleracea contains a wide array of vegetables including broccoli, cauliflower, collard greens, and brussels sprouts. All kale is in the group Brassica oleracea except Red Russian which is a more tender leafed kale in the family of brassica napus pabularia.
Kale is considered to be a highly nutritious vegetable which is high in proteins with powerful antioxidant properties; kale is considered to be anti-inflammatory.
Kale is very high in beta carotene, vitamin K, vitamin C, lutein, zeaxanthin, and reasonably rich in calcium.
Kale, as with broccoli and other brassicas, contains sulforaphane (particularly when chopped or minced), a chemical believed to have potent anti-cancer properties. Boiling decreases the level of the anti-cancer compounds; however, steaming, microwaving, or stir frying do not result in significant loss. Along with other brassica vegetables, kale is also a source of indole-3-carbinol, a chemical which boosts DNA repair in cells and appears to block the growth of cancer cells. Kale is also a good source of carotenoids.