I would suggest a tax on high fructose corn syrup (HFCS). That shit is killing people, and incidentally most of the sugar content of pop and "sugary" drinks.
HFCS is also in some food so it would help there as well.
"The most merciful thing in the world, I think, is the inability of the human mind to correlate all its contents... some day the piecing together of dissociated knowledge will open up such terrifying vistas of reality, and of our frightful position therein, that we shall either go mad from the revelation or flee from the light into the peace and safety of a new Dark Age."
-H.P. Lovecraft