The modern western diet is mostly made of vegetable oils, caffeine containing leaves and beans, huge amounts of refined sugar, ridiculous quantities of grains, antibiotic infused meats, fruit juices, milks, fermented products, huge amounts of corn syrup. Its no great challenge to go to the store for groceries and come home with nothing not on the list above, yet almost none of it existed more than a couple centuries ago. I realize this is considered an incredibly controversial opinion; I assume "most people" strongly believe our ancestors in 8000 BC mostly ate McDonalds and drank MtDew for every meal.