[Turing_Machine]

Maybe when it comes to adults, but we do have a good idea for babies. Lots of them eat nothing but formula and do okay (though not as well as on as human milk, let me hasten to add).

There was a case a number of years ago where one of the formula makers didn't add enough chlorides, resulting in cases of chloride deficiency (previously unknown -- salt is everywhere in a normal diet, and is present in human milk).

So... while maybe we can't say that we have a maximally healthy artificial diet, we do have multiple instances of artificial diets that are good enough to survive on.