if you get a 100% whey, 100% soy, or Egg protein powders, it's natural! Get quality, and you can easily get lots of protein and not worry about extra stuff. Your health food store has unflavored powders too, so you don't even have to worry about artificial flavorings!
Only extra thing I'd suggest - if you decide to go with powders instead (good choice), spread your servings out. If one scoop contains ~20g, take one scoop at a time, not a bunch at once...it's a lot of protein for your tummy to take in and digest if you do it all together.
Good luck!