Sue:
All my vegetables are virtually insect free in the early spring.
I can't remember ever having to spray cole crops until my cabbage heads were fairly mature in early summer. I munch many of cole crops right out in the garden and have never encountered any extra protein!
Much different in summer and fall until some cool nights. Cabbage worms can really strip the plants quick.
The good news . . . cabbage worms are really easy to control with Bt which is really safe to use. (I use the mosquito version of Bt too with great results.)