How To Store Vegitable Which Chopped On Previous Day Night.

Hi All,
I chopped all veggies even onions and tomatos for tomarrow on the previous day night. Because my office is by 8 A.M. I have to prepare tiffin and luch boxes to my hubby and small kid. I have feed to my kid in the morning, then i move to ofice.

But every one saying that , if i chopped previous day all nutritional values will go. I kept chopped veggies in tupper wear boxes and in fridge. Please give me your advices.