And besides that consumables that aren't labelled dangerous by the USDA or FDA (I don't know how they factor into this discussion - not everyone lives in the US, and I see them mentioned in the article) can still be dangerous to an individual if you have a certain condition. Easy example: nut allergies. Others: Celiac disease, diabetes. etc.

And, eating nothing but something that might even be considered healthy can also be fatal if you don't supplement it, no matter how moderate your intake.