For example, killing is forbidden, except euthanasia (in certain countries). Hedge funds can exist, but they can't do any marketing and can only have "sophisticated" investors. In Sweden, alcohol is only sold by special stores.
I'd advocate the same approach to health & food safety. Businesses can sell everything, but there should be limits on (1) marketing (can't market sugar to kids, if at all), (2) taxes (more sugar, more tax - similar to tobacco), (3) general availability (can't buy cigarettes under 18), and (4) labeling (I support labeling of GMOs and of even trace amounts of trans fat).
Edit: especially number 4 above - I see no reason that a honest business would ever see information disclosure regulation as a negative thing; in addition, availability of (trustworthy) information will only increase the economic activity and decrease economic waste (again, only applies to honest companies and products).