Join Date: Oct 2006
from the nyt's
January 28, 2007
By MICHAEL POLLAN
Eat food. Not too much. Mostly plants.
That, more or less, is the short answer to the supposedly incredibly complicated and confusing question of what we humans should eat in order to be maximally healthy. I hate to give away the game right here at the beginning of a long essay, and I confess that I'm tempted to complicate matters in the interest of keeping things going for a few thousand more words. I'll try to resist but will go ahead and add a couple more details to flesh out the advice. Like: A little meat won't kill you, though it's better approached as a side dish than as a main. And you're much better off eating whole fresh foods than processed food products. That's what I mean by the recommendation to eat "food." Once, food was all you could eat, but today there are lots of other edible foodlike substances in the supermarket. These novel products of food science often come in packages festooned with health claims, which brings me to a related rule of thumb: if you're concerned about your health, you should probably avoid food products that make health claims. Why? Because a health claim on a food product is a good indication that it's not really food, and food is what you want to eat.
Uh-oh. Things are suddenly sounding a little more complicated, aren't they? Sorry. But that's how it goes as soon as you try to get to the bottom of the whole vexing question of food and health. Before long, a dense cloud bank of confusion moves in. Sooner or later, everything solid you thought you knew about the links between diet and health gets blown away in the gust of the latest study.
Last winter came the news that a low-fat diet, long believed to protect against breast cancer, may do no such thing — this from the monumental, federally financed Women's Health Initiative, which has also found no link between a low-fat diet and rates of coronary disease. The year before we learned that dietary fiber might not, as we had been confidently told, help prevent colon cancer. Just last fall two prestigious studies on omega-3 fats published at the same time presented us with strikingly different conclusions. While the Institute of Medicine stated that "it is uncertain how much these omega-3s contribute to improving health" (and they might do the opposite if you get them from mercury-contaminated fish), a Harvard study declared that simply by eating a couple of servings of fish each week (or by downing enough fish oil), you could cut your risk of dying from a heart attack by more than a third — a stunningly hopeful piece of news. It's no wonder that omega-3 fatty acids are poised to become the oat bran of 2007, as food scientists micro-encapsulate fish oil and algae oil and blast them into such formerly all-terrestrial foods as bread and tortillas, milk and yogurt and cheese, all of which will soon, you can be sure, sprout fishy new health claims. (Remember the rule?)
By now you're probably registering the cognitive dissonance of the supermarket shopper or science-section reader, as well as some nostalgia for the simplicity and solidity of the first few sentences of this essay. Which I'm still prepared to defend against the shifting winds of nutritional science and food-industry marketing. But before I do that, it might be useful to figure out how we arrived at our present state of nutritional confusion and anxiety.
The story of how the most basic questions about what to eat ever got so complicated reveals a great deal about the institutional imperatives of the food industry, nutritional science and — ahem — journalism, three parties that stand to gain much from widespread confusion surrounding what is, after all, the most elemental question an omnivore confronts. Humans deciding what to eat without expert help — something they have been doing with notable success since coming down out of the trees — is seriously unprofitable if you're a food company, distinctly risky if you're a nutritionist and just plain boring if you're a newspaper editor or journalist. (Or, for that matter, an eater. Who wants to hear, yet again, "Eat more fruits and vegetables"?) And so, like a large gray fog, a great Conspiracy of Confusion has gathered around the simplest questions of nutrition — much to the advantage of everybody involved. Except perhaps the ostensible beneficiary of all this nutritional expertise and advice: us, and our health and happiness as eaters.
FROM FOODS TO NUTRIENTS
It was in the 1980s that food began disappearing from the American supermarket, gradually to be replaced by "nutrients," which are not the same thing. Where once the familiar names of recognizable comestibles — things like eggs or breakfast cereal or cookies — claimed pride of place on the brightly colored packages crowding the aisles, now new terms like "fiber" and " cholesterol " and "saturated fat" rose to large-type prominence. More important than mere foods, the presence or absence of these invisible substances was now generally believed to confer health benefits on their eaters. Foods by comparison were coarse, old-fashioned and decidedly unscientific things — who could say what was in them, really? But nutrients — those chemical compounds and minerals in foods that nutritionists have deemed important to health — gleamed with the promise of scientific certainty; eat more of the right ones, fewer of the wrong, and you would live longer and avoid chronic diseases.
Nutrients themselves had been around, as a concept, since the early 19th century, when the English doctor and chemist William Prout identified what came to be called the "macronutrients": protein, fat and carbohydrates. It was thought that that was pretty much all there was going on in food, until doctors noticed that an adequate supply of the big three did not necessarily keep people nourished. At the end of the 19th century, British doctors were puzzled by the fact that Chinese laborers in the Malay states were dying of a disease called beriberi, which didn't seem to afflict Tamils or native Malays. The mystery was solved when someone pointed out that the Chinese ate "polished," or white, rice, while the others ate rice that hadn't been mechanically milled. A few years later, Casimir Funk, a Polish chemist, discovered the "essential nutrient" in rice husks that protected against beriberi and called it a "vitamine," the first micronutrient. Vitamins brought a kind of glamour to the science of nutrition, and though certain sectors of the population began to eat by its expert lights, it really wasn't until late in the 20th century that nutrients managed to push food aside in the popular imagination of what it means to eat.
No single event marked the shift from eating food to eating nutrients, though in retrospect a little-noticed political dust-up in Washington in 1977 seems to have helped propel American food culture down this dimly lighted path. Responding to an alarming increase in chronic diseases linked to diet — including heart disease, cancer and diabetes — a Senate Select Committee on Nutrition, headed by George McGovern, held hearings on the problem and prepared what by all rights should have been an uncontroversial document called "Dietary Goals for the United States." The committee learned that while rates of coronary heart disease had soared in America since World War II, other cultures that consumed traditional diets based largely on plants had strikingly low rates of chronic disease. Epidemiologists also had observed that in America during the war years, when meat and dairy products were strictly rationed, the rate of heart disease temporarily plummeted.
Na�vely putting two and two together, the committee drafted a straightforward set of dietary guidelines calling on Americans to cut down on red meat and dairy products. Within weeks a firestorm, emanating from the red-meat and dairy industries, engulfed the committee, and Senator McGovern (who had a great many cattle ranchers among his South Dakota constituents) was forced to beat a retreat. The committee's recommendations were hastily rewritten. Plain talk about food — the committee had advised Americans to actually "reduce consumption of meat" — was replaced by artful compromise: "Choose meats, poultry and fish that will reduce saturated-fat intake."
A subtle change in emphasis, you might say, but a world of difference just the same. First, the stark message to "eat less" of a particular food has been deep-sixed; don't look for it ever again in any official U.S. dietary pronouncement. Second, notice how distinctions between entities as different as fish and beef and chicken have collapsed; those three venerable foods, each representing an entirely different taxonomic class, are now lumped together as delivery systems for a single nutrient. Notice too how the new language exonerates the foods themselves; now the culprit is an obscure, invisible, tasteless — and politically unconnected — substance that may or may not lurk in them called "saturated fat."
The linguistic capitulation did nothing to rescue McGovern from his blunder; the very next election, in 1980, the beef lobby helped rusticate the three-term senator, sending an unmistakable warning to anyone who would challenge the American diet, and in particular the big chunk of animal protein sitting in the middle of its plate. Henceforth, government dietary guidelines would shun plain talk about whole foods, each of which has its trade association on Capitol Hill, and would instead arrive clothed in scientific euphemism and speaking of nutrients, entities that few Americans really understood but that lack powerful lobbies in Washington. This was precisely the tack taken by the National Academy of Sciences when it issued its landmark report on diet and cancer in 1982. Organized nutrient by nutrient in a way guaranteed to offend no food group, it codified the official new dietary language. Industry and media followed suit, and terms like polyunsaturated, cholesterol, monounsaturated, carbohydrate, fiber, polyphenols, amino acids and carotenes soon colonized much of the cultural space previously occupied by the tangible substance formerly known as food. The Age of Nutritionism had arrived.
THE RISE OF NUTRITIONISM
The first thing to understand about nutritionism — I first encountered the term in the work of an Australian sociologist of science named Gyorgy Scrinis — is that it is not quite the same as nutrition. As the "ism" suggests, it is not a scientific subject but an ideology. Ideologies are ways of organizing large swaths of life and experience under a set of shared but unexamined assumptions. This quality makes an ideology particularly hard to see, at least while it's exerting its hold on your culture. A reigning ideology is a little like the weather, all pervasive and virtually inescapable. Still, we can try.
In the case of nutritionism, the widely shared but unexamined assumption is that the key to understanding food is indeed the nutrient. From this basic premise flow several others. Since nutrients, as compared with foods, are invisible and therefore slightly mysterious, it falls to the scientists (and to the journalists through whom the scientists speak) to explain the hidden reality of foods to us. To enter a world in which you dine on unseen nutrients, you need lots of expert help.
But expert help to do what, exactly? This brings us to another unexamined assumption: that the whole point of eating is to maintain and promote bodily health. Hippocrates's famous injunction to "let food be thy medicine" is ritually invoked to support this notion. I'll leave the premise alone for now, except to point out that it is not shared by all cultures and that the experience of these other cultures suggests that, paradoxically, viewing food as being about things other than bodily health — like pleasure, say, or socializing — makes people no less healthy; indeed, there's some reason to believe that it may make them more healthy. This is what we usually have in mind when we speak of the "French paradox" — the fact that a population that eats all sorts of unhealthful nutrients is in many ways healthier than we Americans are. So there is at least a question as to whether nutritionism is actually any good for you.
Another potentially serious weakness of nutritionist ideology is that it has trouble discerning qualitative distinctions between foods. So fish, beef and chicken through the nutritionists' lens become mere delivery systems for varying quantities of fats and proteins and whatever other nutrients are on their scope. Similarly, any qualitative distinctions between processed foods and whole foods disappear when your focus is on quantifying the nutrients they contain (or, more precisely, the known nutrients).
This is a great boon for manufacturers of processed food, and it helps explain why they have been so happy to get with the nutritionism program. In the years following McGovern's capitulation and the 1982 National Academy report, the food industry set about re-engineering thousands of popular food products to contain more of the nutrients that science and government had deemed the good ones and less of the bad, and by the late '80s a golden era of food science was upon us. The Year of Eating Oat Bran — also known as 1988 — served as a kind of coming-out party for the food scientists, who succeeded in getting the material into nearly every processed food sold in America. Oat bran's moment on the dietary stage didn't last long, but the pattern had been established, and every few years since then a new oat bran has taken its turn under the marketing lights. (Here comes omega-3!)
By comparison, the typical real food has more trouble competing under the rules of nutritionism, if only because something like a banana or an avocado can't easily change its nutritional stripes (though rest assured the genetic engineers are hard at work on the problem). So far, at least, you can't put oat bran in a banana. So depending on the reigning nutritional orthodoxy, the avocado might be either a high-fat food to be avoided (Old Think) or a food high in monounsaturated fat to be embraced (New Think). The fate of each whole food rises and falls with every change in the nutritional weather, while the processed foods are simply reformulated. That's why when the Atkins mania hit the food industry, bread and pasta were given a quick redesign (dialing back the carbs; boosting the protein), while the poor unreconstructed potatoes and carrots were left out in the cold.
Of course it's also a lot easier to slap a health claim on a box of sugary cereal than on a potato or carrot, with the perverse result that the most healthful foods in the supermarket sit there quietly in the produce section, silent as stroke victims , while a few aisles over, the Cocoa Puffs and Lucky Charms are screaming about their newfound whole-grain goodness.
EAT RIGHT, GET FATTER
So nutritionism is good for business. But is it good for us? You might think that a national fixation on nutrients would lead to measurable improvements in the public health. But for that to happen, the underlying nutritional science, as well as the policy recommendations (and the journalism) based on that science, would have to be sound. This has seldom been the case.
Consider what happened immediately after the 1977 "Dietary Goals" — McGovern's masterpiece of politico-nutritionist compromise. In the wake of the panel's recommendation that we cut down on saturated fat, a recommendation seconded by the 1982 National Academy report on cancer, Americans did indeed change their diets, endeavoring for a quarter-century to do what they had been told. Well, kind of. The industrial food supply was promptly reformulated to reflect the official advice, giving us low-fat pork, low-fat Snackwell's and all the low-fat pasta and high-fructose (yet low-fat!) corn syrup we could consume. Which turned out to be quite a lot. Oddly, America got really fat on its new low-fat diet — indeed, many date the current obesity and diabetes epidemic to the late 1970s, when Americans began binging on carbohydrates, ostensibly as a way to avoid the evils of fat.
This story has been told before, notably in these pages ("What if It's All Been a Big Fat Lie? " by Gary Taubes, July 7, 2002), but it's a little more complicated than the official version suggests. In that version, which inspired the most recent Atkins craze, we were told that America got fat when, responding to bad scientific advice, it shifted its diet from fats to carbs, suggesting that a re-evaluation of the two nutrients is in order: fat doesn't make you fat; carbs do. (Why this should have come as news is a mystery: as long as people have been raising animals for food, they have fattened them on carbs.)
But there are a couple of problems with this revisionist picture. First, while it is true that Americans post-1977 did begin binging on carbs, and that fat as a percentage of total calories in the American diet declined, we never did in fact cut down on our consumption of fat. Meat consumption actually climbed. We just heaped a bunch more carbs onto our plates, obscuring perhaps, but not replacing, the expanding chunk of animal protein squatting in the center.
How did that happen? I would submit that the ideology of nutritionism deserves as much of the blame as the carbohydrates themselves do — that and human nature. By framing dietary advice in terms of good and bad nutrients, and by burying the recommendation that we should eat less of any particular food, it was easy for the take-home message of the 1977 and 1982 dietary guidelines to be simplified as follows: Eat more low-fat foods. And that is what we did. We're always happy to receive a dispensation to eat more of something (with the possible exception of oat bran), and one of the things nutritionism reliably gives us is some such dispensation: low-fat cookies then, low-carb beer now. It's hard to imagine the low-fat craze taking off as it did if McGovern's original food-based recommendations had stood: eat fewer meat and dairy products. For how do you get from that stark counsel to the idea that another case of Snackwell's is just what the doctor ordered?
But if nutritionism leads to a kind of false consciousness in the mind of the eater, the ideology can just as easily mislead the scientist. Most nutritional science involves studying one nutrient at a time, an approach that even nutritionists who do it will tell you is deeply flawed. "The problem with nutrient-by-nutrient nutrition science," points out Marion Nestle, the New York University nutritionist, "is that it takes the nutrient out of the context of food, the food out of the context of diet and the diet out of the context of lifestyle."
If nutritional scientists know this, why do they do it anyway? Because a nutrient bias is built into the way science is done: scientists need individual variables they can isolate. 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. So if you're a nutritional scientist, you do the only thing you can do, given the tools at your disposal: break the thing down into its component parts and study those one by one, even if that means ignoring complex interactions and contexts, as well as the fact that the whole may be more than, or just different from, the sum of its parts. This is what we mean by reductionist science.
Scientific reductionism is an undeniably powerful tool, but it can mislead us too, especially when applied to something as complex as, on the one side, a food, and on the other, a human eater. It encourages us to take a mechanistic view of that transaction: put in this nutrient; get out that physiological result. Yet people differ in important ways. Some populations can metabolize sugars better than others; depending on your evolutionary heritage, you may or may not be able to digest the lactose in milk. The specific ecology of your intestines helps determine how efficiently you digest what you eat, so that the same input of 100 calories may yield more or less energy depending on the proportion of Firmicutes and Bacteroidetes living in your gut. There is nothing very machinelike about the human eater, and so to think of food as simply fuel is wrong.
Also, people don't eat nutrients, they eat foods, and foods can behave very differently than the nutrients they contain. Researchers have long believed, based on epidemiological comparisons of different populations, that a diet high in fruits and vegetables confers some protection against cancer. So naturally they ask, What nutrients in those plant foods are responsible for that effect? One hypothesis is that the antioxidants in fresh produce — compounds like beta carotene, lycopene, vitamin E, etc. — are the X factor. It makes good sense: these molecules (which plants produce to protect themselves from the highly reactive oxygen atoms produced in photosynthesis) vanquish the free radicals in our bodies, which can damage DNA and initiate cancers. At least that's how it seems to work in the test tube. Yet as soon as you remove these useful molecules from the context of the whole foods they're found in, as we've done in creating antioxidant supplements, they don't work at all. Indeed, in the case of beta carotene ingested as a supplement, scientists have discovered that it actually increases the risk of certain cancers. Big oops.
What's going on here? We don't know. It could be the vagaries of human digestion. Maybe the fiber (or some other component) in a carrot protects the antioxidant molecules from destruction by stomach acids early in the digestive process. Or it could be that we isolated the wrong antioxidant. Beta is just one of a whole slew of carotenes found in common vegetables; maybe we focused on the wrong one. Or maybe beta carotene works as an antioxidant only in concert with some other plant chemical or process; under other circumstances, it may behave as a pro-oxidant.
Indeed, to look at the chemical composition of any common food plant is to realize just how much complexity lurks within it. Here's a list of just the antioxidants that have been identified in garden-variety thyme: