This is rule #19 in Michael Pollan’s book “Food Rules: An Eater’s Manual”. One of my favorites.
It stresses out the importance of eating real food, not creations of the food-industrial complex. Real food doesn’t have a long ingredient list, isn’t advertised on national television, and doesn’t contain stuff you can’t even pronounce the name.
Part of being healthy means consciously choosing wisely what you put in your mouth. So do eat food that comes from plants not that is made in plants!