Would this be a good idea for an advent calendar?

I got a advent calendar that you can put your own treats or items in. It is cloth and doesnt close completely. I was thinking of putting my son daily gummy bear vitamins in it and have him open it everyday and that will be his treat. Would it take the nutrients out of the gummy vitamin if it is exposed to the air for a few weeks and days? I just want to fill it and forget about it, I dotn want to out a vitamin in it daily. I dont want to put candy in it and small toys arent an option in our house right now with a newborn. Any suggestions?