If I'm foolish here, then I am to still be less foolish than someone who doesn't know when to simply keep their opinion to themselves.

It's more reasonable to believe it depends on the person, since why wouldn't it.

Because saying "it depends on the person" is akin to saying "there are too many (possibly unknown) variables at play to actually figure out what causes what".

Nutritional sciences have it hard. it's basically impossible to really isolate cause and effect while staying moral with complex organisms like humans

Especially because it might not be up to the human, since our digestion relies on symbiotic gut bacteria, which we don’t have good ways to test what they even are.