If you have no other choice, use them, but frozen are far better, easier to use as to measuring.

Some beleive that the frozen veggies have a higher Vit. content as MOST Co.'s pick, then freeze in the same day, so it's not been sitting in a truck for days, then the store, then our fridges.
Canned may be the same way, if its a good brand, but like Doreen says it's the hidden stuff.

What ever works best for your schedule, Cheers Kathy