> I couldn't keep them out of the grains and
> sweets if I wanted to -- our whole society is built around them.  But I
> can educate them that there are better choices.

Aye, there's the rub. Make a food forbidden, and it becomes something they
really want, and will often go great lengths to get. Allow them to eat the
food, and they believe they are eating it with your blessing.

It's a can't win scenario.