Why spring greens are good for you

Spring greens – not to be confused with other green leaves that grow at this time of year – are the most biddable type of cabbage. Similar to a cos lettuce in shape, but looser in form, and without much of a heart, they don't have the fibrous crunch of round cabbages.
If you show them steam, or blanch them in boiling water, spring greens positively swoon. They have a silky-soft texture, and taste sweeter and fresher than the robust, hearted cabbages we associate with winter, so they fit well with lighter spring and summer cooking.
There's no need to chop them: you can just serve them whole. But if you roll up the leaves, shred them finely, then fry them, you get a dead ringer for the crispy seaweed served in Chinese restaurants. 
Why are spring greens good for me?
You can't eat enough of them. Spring greens belong to the brassica family, whose prodigious health benefits are well documented. They provide you with a seriously useful amount of vitamin C, to support your immune system, and vitamin K, to build bone strength.
They also contain natural compounds, such as sulforaphane and indoles. A body of evidence suggests these plant chemicals have a significant anti-cancer action, and anti-inflammatory properties, which could help protect against heart disease and stroke. To make the most of the nutrients in spring greens, refrigerate them and eat as close to purchase as possible.

Source  - Guardian