Is it true that you might feel worse before you feel better if you're on a new vitamin regimen?

I just started taking this stuff called Dual Action Cleanse and I I've been feeling sick. Of course I know it could be a coincidence but I could have sworn I heard somewhere that it is common to feel sick when on a new vitamin program and that sometimes you feel worse before you feel better. Does anyone have any medical info to back this statement up? I'm very curious. To be specific the program consists of a multi-vitamin, a green tea capsule and colon cleansing herb caplets.