Only this would be worse. Someone can choose to buy Soylent or use Theranos for themselves and no one else gets hurt. If you a person buys a crappy self driving car system it could kill me, a totally unrelated person.

I don't care how much of a libertarian you are, that's exactly the reason why we have regulations.

Technically, Soylent abides by regulations: they sell flaxseed mixed with peas and oat (I think: I’m in Europe and eat Huel, which has mostly those). None of those are not well-known food sources. There are no regulation about claiming that eating nothing but that is safe; they should (at least, Huel does) have the recommended daily doses of each major molecule on the bag.