In the Netherlands, a traditional winter dish called "boerenkoolstamppot" is a mix of curly kale and mashed potatoes, sometimes with fried bacon, and served with rookworst ("smoked sausage").
In Northern Germany, there is a winter tradition known as "Kohlfahrt" ("kale trip"), where a group of people will go on a hike through the woods during the day before gathering at an inn or private residence where kale is served, usually with bacon and Kohlwurst ("kale sausage"). Kale is considered a Northern German staple and comfort food.
In Italy, cavolo nero kale is an ingredient of the Tuscan soup ribollita.
A traditional Portuguese soup, caldo verde, combines pureed potatoes, very finely sliced kale, olive oil and salt. Additional ingredients can include broth and sliced, cooked spicy sausage.
In Scotland, kale provided such a base for a traditional diet that the word in some Scots dialects is synonymous with food. To be "off one's kail" is to feel too ill to eat.
In Ireland, kale is mixed with mashed potatoes to make the traditional dish colcannon. It is popular on Halloween, when it may be served with sausages.
In Sri Lanka, it is known as kola gova or ela gova. It is cultivated for edible use. A dish called 'kale mallung' is served almost everywhere in the island along with rice.
Kale is a source of the carotenoids, lutein and zeaxanthin (tables). As with broccoli and other cruciferous vegetables, kale contains glucosinolate compounds, such as glucoraphanin, which contributes to the formation of sulforaphane, a compound under preliminary research for its potential to affect human health beneficially.
Boiling kale decreases the level of glucosinate compounds, whereas steaming, microwaving or stir frying does not cause significant loss. Kale is high in oxalic acid, the levels of which can be reduced by cooking.
Kale contains high levels of polyphenols, such as ferulic acid, with levels varying due to environmental and genetic factors.
Kale originated in the eastern Mediterranean and Anatolia, where it was cultivated for food beginning by 2000 BCE at the latest. Curly-leaved varieties of cabbage already existed along with flat-leaved varieties in Greece in the 4th century BC. These forms, which were referred to by the Romans as Sabellian kale, are considered to be the ancestors of modern kales.
