Everything you know about food is wrong. Not only that, everything the people making your food know is probably wrong too.
Michael Pollan's In Defense of Food illustrates how poorly understood the field of food science is and ignorance corrupts our eating habits. Scientists try to reduce everything down to soil to their essential few components and then build "nutrients" -- not "food" -- accordingly. Soil is reduced to just potassium, phosphorous and nitrogen. The plants that soil produces suffer from a lack of nutritional diversity, and then the meat animals that eat those plants do as well. To compensate, scientists sprinkle on top whatever nutrients are popular at the moments and market it as "healthy" "food".
The big problem, Pollan shows, is that a lot of the benefits in food exist in the synergy between many food elements coming together, rather than in the right combination of five or so ingredients. To function properly, the human body needs an astonishing amount of different compounds, the spectrum of which are available in common food has been severely limited by the industrialization of production. Whereas in previous generations, many varieties of crops were planted and consumed, now industrialization has led to convergence. The dominant crops were selected for their ability to produce, not nutritional value, and the fact that they are always in season means that the usual shifts in diets are stabilized to a few homogeneous crops.
The most alarming part of what Pollan shows is how much of the supermarket is now filled with imitation food -- colorful concoctions of chemicals, additives, food colouring, and sugar that generations-past would not even recognize as being edible. After seeing Food Inc. (which shows how almost the entire supermarket consists of corn mascaraing as everything from cereal to pancake syrup) and reading this book, I felt like I could see into the Matrix. Everyone around me was eating-- but they weren't eating food. It was all an illusion. What they thought as a proper meal was really fried red meat (non-grass fed), with bread (robbed of its nutrients), fried potatoes, and a corn syrup-filled artificial drink.
What's the way forward? Pollan says that we should read the ingredients lists and if we see corn syrup, a word we can't pronounce, or more than 10 ingredients, we should leave it on the shelf. Certifications labeling food as "healthy" are all to be treated as suspect due to the fact that research studies into the nutritional value of food are paid for and influenced by the companies that commission them. If you want to eat healthy, follow Pollan's advice: "Eat food (not 'nutrients' or 'imitation food'). Not too much. Mostly plants. And nothing your great-grand parents wouldn't recognize as food.
As someone who admires the work of Norman Borlaug in vastly increasing the yield and strength of crops in order to feed the world's hungry poor, I tended to view the organic movement as hippie misadventure. But reading this book has changed my thinking. If you have the money, buy organic. Go to the farmer's market. Prepare your own food. If you don't, at least avoid the things things that don't look natural. The food we have may keep us from starving to death, but that doesn't mean that it isn't killing us.