This week marks the publication of Michael Pollan's In Defense of Food: An Eater's Manifesto, the book-length expansion of an essay he wrote last January. (Read a review of the book by Slate's Laura Shapiro.) In a "Science" column published a year ago and reprinted below, Daniel Engber disputed Pollan's central thesis.
Adam and Eve must have been a healthy pair. They got some exercise, ate lots of locally grown fruits and vegetables, and while they may not have been thin by today's fashion standards, they certainly weren't ashamed of their bodies. Now look what's happened: In just 6,000 years, we've abandoned their sensible eating habits for a high-fat, sugar-loaded diet, and turned ourselves into a nation of lard-asses. Goodbye Garden of Eden; hello Olive Garden.
Whence our fall from grace? According to Michael Pollan's essay in last Sunday's New York Times Magazine, the serpent wears a lab coat. For decades scientists have been analyzing the food we eat, breaking it down into component parts, and studying how each nutrient affects our health in controlled conditions. More often than not, the "expert advice" that emerged from this work did more harm than good, it seems. When the government told us to eat more low-fat foods, we ended up binging on carbs. We bought margarine when the gurus told us to avoid saturated fats; now city governments are telling us that margarine is against the law. Well-intentioned blunders like these have crowded out the ancient wisdom that once guided our culinary habits, Pollan argues.
Blame the scientists. They "need individual variables they can isolate," Pollan explains. "Yet even the simplest food is a hopelessly complex thing to study, a virtual wilderness of chemical compounds, many of which exist in complex and dynamic relation to one another, and all of which together are in the process of changing from one state to another." We'll never understand the biology of eating because it's just too hard to study in the lab. Large-scale clinical investigations won't be much help, either: There's no good way to observe or control how people eat; when doctors ask us about our diets we either misremember or make up stuff.
That much may be true, but it doesn't mean there's an inherent flaw in the scientific method. An optimist would say the worst years are behind us. Sure, we've made a few mistakes, but the science is getting stronger every day. Just as the discovery of vitamins made it easier to treat beriberi and scurvy, so will the latest research eventually help us to vanquish coronary heart disease and diabetes. That's how science works: You keep plugging away in the lab until you finally get somewhere.
It would help me to accept Pollan's claim to the contrary if I could think of any other topic in the universe so complicated that it defies scientific investigation. Yes, there's a lot to consider when you're looking at nutrition. But is climatology any easier? Should we throw up our hands at the idea of studying global warming, simply because it reflects a wilderness of variables in complex and dynamic relation to one another? Once we might have charged psychology with the same crimes here ascribed to nutrition: The mind is too complex, and individuals too unreliable, for us ever to understand what goes on inside our heads. But surely we've now seen the benefits of opening the black box—and tinkering around with the 100 billion neurons of the human brain.
Pollan presents the food scientist as a reductionist bogeyman, trampling willy-nilly over the delicate complexities of the natural world. (The illustrations assigned to his article convey dread at the notion that a fruit might be reduced—gasp—to its constituent parts.) It's a dangerous path, he argues, since those complexities have kept us alive over the course of human history. We don't have to identify which of the three-dozen antioxidants in a sprig of thyme, for example, will protect us from cancer; if we've always been eating fruits and vegetables, then they must be good for us. It's natural selection of the human diet: Thousands of years of trial and error must have pushed us toward increasingly wholesome foods. Any unhealthy eating habits would have gone extinct along the way. Why toss out these extraordinary evolutionary data in favor of a few decades' worth of lab experiments?
But Pollan's nutritional Darwinism only makes sense if the selection pressures of the distant past were in perfect alignment with the health concerns of today. In other words, our food culture would have evolved to protect us from cancer, heart disease, and obesity only if those maladies had been a primary threat to reproduction in the ancient world. It's hard to imagine that the risks posed by these so-called "diseases of affluence"—which often strike late in life, after we've had babies—would have been as significant to our fast-living, sickly forebears as the dangers of, say, bacterial infections or the occasional drought. Indeed, for much of human history, natural selection might well have traded off the dangers of morbid obesity to mitigate the risk of starvation. There's just no way to know how the ancient culinary traditions will fare in the modern world until we try them.
Modern nutrition may be more of an ideology than a science, but so is Pollan's nutritional Darwinism. The two ideologies stand in direct opposition to one another, with the science-minded progressives on one side and the culinary conservatives on the other. The Darwinists reject the idea that lab science can be used to engineer public health on a massive scale. They rely instead on the time-tested mores that have always been our guides. Pollan's reflections on the diet revolution could be an homage to Edmund Burke: Our radical eating habits have produced a swinish multitude.
A conservative approach to eating seems very straightforward, which gives it an enormous appeal. We'd be healthier, Pollan argues, if we just stopped thinking and worrying so much about food and let nature take its course. (He takes several opportunities to congratulate the svelte, chain-smoking French for their pleasure-based cuisine.) But there's no reason to believe that nutritional Darwinism will give us any more clarity on its own terms.
Health gurus routinely use the same language of ancient culinary traditions to sell fad diets that would make Pollan cringe. Barry Sears, author of the low-carb Zone diet, suggests a return to the traditional food culture of the "Neo-Paleolithic" period, when caveman "decathletes" consumed large amounts of meat and very little grain. In his version, we bungled up the natural selection of foodstuffs when we invented agriculture. Pollan says that happened during the Industrial Revolution. Two evolutionary stories offer very different nutritional advice. How can we know who's right?
If we had only the rhetoric of natural selection to go by, we'd never know for sure. Lucky for us, humans have gradually developed the means—over centuries of cultural evolution, no less—to evaluate one claim against another on the basis of objective facts. For all its foibles, food science has given us a reliable set of data on what works and what doesn't. As Ben Goldacre points out in the New Statesman, solid epidemiological work has validated the standard advice we get from our doctors: Exercise more and eat your fruits and vegetables.
Pollan cites the same scientific research to support what he describes as his "flagrantly unscientific" diet plan: "Eat food. Not too much. Mostly plants." I'm happy to follow those dicta if they'll help me to live a longer, happier life. But that doesn't mean I have to buy into the misleading, great-great-grandma-knew-best philosophy that spawned them. I'd rather stick to the science, warts and all.