I would have to say no. Not because I don't believe it's harmful, but because I dislike when the government acts as a babysitter and outlaws something. I believe individuals should have the right to make their own decisions, regardless of whether the government determines it's unhealthy. I take this stance in part because what may be bad for most people can be great for certain individuals. But the biggest reason is I believe individuals should be free to make their own decisions as long as they don't infringe on someone else's rights. I don't see how advertising infringes on another person's rights, therefore I believe it should be legal.
I think ads, in general, should not be shown to children. I do not allow my kids to watch TV. If they want to watch a program, they watch it through my computer on a stream where no ads are present. I don't like the idea of forcing commercialism on kids.