Does powdered chocolate milk mix deplete the nutrients from milk?

Well, I just heard my dad and stepmom say something sort of outrageous. According to them, adding chocolate milk mix to milk takes some of the nutrients out. Because of this, they now buy the syrup kind. I call serious BS on this, as the syrup has waaaaay more sugar and it has HFCS. If any of you could throw some articles my way, or if you have a degree in nutrition and could tell me some facts (preferably with some actual science, not just "believe me because I have a degree" BS), I'd really appreciate it.