Out in nature, if you're a creature looking for something to eat, you might see some attractive looking red berries and think to yourself, "I wonder if I can eat those without getting sick? And what about those mushrooms?" Well, the same thing is happening in the supermarket. There are many tasty things, some of which can kill you. Trans fats, for example, or all the sugar we're eating.
So we're back where we were once upon a time, trying to navigate a treacherous food landscape -- full of attractive things, but some of which are liable to shorten our lives.