Our scientists response is that you should NEVER inject food coloring into your veins.

From my part (I am the ScienceLine Moderator), I would say that you should never try to do any experimentation on your body, less to inject anything into your bloodstream. Food coloring is something that does not have to be inside your veins for any reason. And as our scientist said, no, it will not change the color of your blood in any perceptible way.