Kale, also referred to as leaf cabbage
Rich source of vitamin A, vitamin B6, vitamin C, folate and manganese and a moderate source of vitamin B1, vitamin B2, vitamin B5, vitamin B6, vitamin E, calcium, iron, potassium and phosphorus. Also contains carotenoids and polyphenols, and a glucosinolate which contributes to the formation of sulforaphane.
Boiling reduces sulforaphane levels. However, steaming, microwaving and stir frying does not appear to have any effect on the compounds.