But then again, as I said above, I see business as a privilege, not a right. After all, you could also say that your individual liberty is being infringed by taxes - but you can always move to a deserted island, stop using the services provided by the governments, and pay no tax!
But that is not usually considered libertarian.
A libertarian scheme would usually be like 'certification should be a business, and foods should be certified sugar free by a specific certification company, and bear that company's sugar-free logo'.
Which I think is highly impractical
But then again, as I said above, I see business as a privilege, not a right.
Wow. Stop considering yourself a libertarian, seriously. This is authoritarian talk. All I see you arguing for is rules, and if somone points out their flaws, more and 'smarter' rules. This is the exact opposite of libertarianism.
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).