The Omnivore's Dilemma: A Natural History of Four Meals

by Michael Pollan

It probably would not eat a fifth of its meals in cars or feed fully a third of its children at a fast-food outlet every day.

Our taste buds help too, predisposing us toward sweetness, which signals carbohydrate energy in nature, and away from bitterness, which is how many of the toxic alkaloids produced by plants taste.

Ecology also teaches that all life on earth can be viewed as a competition among species for the solar energy captured by green plants and stored in the form of complex carbon molecules. A food chain is a system for passing those calories on to species that lack the plant’s unique ability to synthesize them from sunlight. One of the themes of this book is that the industrial revolution of the food chain, dating to the close of World War II, has actually changed the fundamental rules of this game. Industrial agriculture has supplanted a complete reliance on the sun for our calories with something new under the sun: a food chain that draws much of its energy from fossil fuels instead. (Of course, even that energy originally came from the sun, but unlike sunlight it is finite and irreplaceable.)

A chicken nugget, for example, piles corn upon corn: what chicken it contains consists of corn, of course, but so do most of a nugget’s other constituents, including the modified corn starch that glues the thing together, the corn flour in the batter that coats it, and the corn oil in which it gets fried. Much less obviously, the leavenings and lecithin, the mono-, di-, and triglycerides, the attractive golden coloring, and even the citric acid that keeps the nugget “fresh” can all be derived from corn.

To wash down your chicken nuggets with virtually any soft drink in the supermarket is to have some corn with your corn. Since the 1980s virtually all the sodas and most of the fruit drinks sold in the supermarket have been sweetened with high-fructose corn syrup (HFCS)—after water, corn sweetener is their principal ingredient. Grab a beer for your beverage instead and you’d still be drinking corn, in the form of alcohol fermented from glucose refined from corn.

Read the ingredients on the label of any processed food and, provided you know the chemical names it travels under, corn is what you will find. For modified or unmodified starch, for glucose syrup and maltodextrin, for crystalline fructose and ascorbic acid, for lecithin and dextrose, lactic acid and lysine, for malto...

There are some forty-five thousand items in the average American supermarket and more than a quarter of them now contain corn.

Forty percent of the calories a Mexican eats in a day comes directly from corn, most of it in the form of tortillas. So when a Mexican says “I am maize” or “corn walking,” it is simply a statement of fact: The very substance of the Mexican’s body is to a considerable extent a manifestation of this plant.

(As one scientist put it, carbon supplies life’s quantity, since it is the main structural element in living matter, while much scarcer nitrogen supplies its quality—but

Originally, the atoms of carbon from which we’re made were floating in the air, part of a carbon dioxide molecule. The only way to recruit these carbon atoms for the molecules necessary to support life—the carbohydrates, amino acids, proteins, and lipids—is by means of photosynthesis. Using sunlight as a catalyst the green cells of plants combine carbon atoms taken from the air with water and elements drawn from the soil to form the simple organic compounds that stand at the base of every food chain. It is more than a figure of speech to say that plants create life out of thin air.

Where most plants during photosynthesis create compounds that have three carbon atoms, corn (along with a small handful of other species) make compounds that have four: hence “C-4,” the botanical nickname for this gifted group of plants, which wasn’t identified until the 1970s. The C-4 trick represents an important economy for a plant, giving it an advantage, especially in areas where water is scarce and temperatures high. In order to gather carbon atoms from the air, a plant has to open its stomata, the microscopic orifices in the leaves through which plants both take in and exhaust gases. Every time a stoma opens to admit carbon dioxide precious molecules of water escape. It’s as though every time you opened your mouth to eat you lost a quantity of blood. Ideally, you would open your mouth as seldom as possible, ingesting as much food as you could with every bite. This is essentially what a C-4 plant does. By recruiting extra atoms of carbon during each instance of photosynthesis, the corn plant is able to limit its loss of water and “fix”—that is, take from the atmosphere and link in a useful molecule—significantly more carbon than other plants.

At its most basic, the story of life on earth is the competition among species to capture and store as much energy as possible—either directly from the sun, in the case of plants, or, in the case of animals, by eating plants and plant eaters. The energy is stored in the form of carbon molecules and measured in calories. The calories we eat, whether in an ear of corn or a steak, represent packets of energy once captured by a plant. The C-4 trick helps explain the corn plant’s success in this competition: Few plants can manufacture quite as much organic matter (and calories) from the same quantities of sunlight and water and basic elements as corn. (Ninety-seven percent of what a corn plant is comes from the air, three percent from the ground.)

Some carbon atoms, called isotopes, have more than the usual complement of six protons and six neutrons, giving them a slightly different atomic weight. C-13, for example, has six protons and seven neutrons. (Hence “C-13.”) For whatever reason, when a C-4 plant goes scavenging for its four-packs of carbon, it takes in more carbon 13 than ordinary—C-3—plants, which exhibit a marked preference for the more common carbon 12. Greedy for carbon, C-4 plants can’t afford to discriminate among isotopes, and so end up with relatively more carbon 13. The higher the ratio of carbon 13 to carbon 12 in a person’s flesh, the more corn has been in his diet—or in the diet of the animals he or she ate. (As far as we’re concerned, it makes little difference whether we consume relatively more or less carbon 13.)

But carbon 13 doesn’t lie, and researchers who have compared the isotopes in the flesh or hair of North Americans to those in the same tissues of Mexicans report that it is now we in the North who are the true people of corn. “When you look at the isotope ratios,” Todd Dawson, a Berkeley biologist who’s done this sort of research, told me, “we North Americans look like corn chips with legs.” Compared to us, Mexicans today consume a far more varied carbon diet: the animals they eat still eat grass (until recently, Mexicans regarded feeding corn to livestock as a sacrilege); much of their protein comes from legumes; and they still sweeten their beverages with cane sugar. So that’s us: processed corn, walking.

double-entry bookkeeping

(Originally “corn” was a generic English word for any kind of grain, even a grain of salt—hence “corned beef” it didn’t take long for Zea mays to appropriate the word for itself, at least in America.)

(Whiskey and pork were both regarded as “concentrated corn,” the latter a concentrate of its protein, the former of its calories; both had the virtue of reducing corn’s bulk and raising its price.)

shelled cobs were burned for heat and stacked by the privy as a rough substitute for toilet paper. (Hence the American slang term “corn hole.”)

Plant a whole corncob and watch what happens: If any of the kernels manage to germinate, and then work their way free of the smothering husk, they will invariably crowd themselves to death before their second set of leaves has emerged. More than most domesticated plants (a few of whose offspring will usually find a way to grow unassisted), corn completely threw its lot in with humanity when it evolved its peculiar husked ear. Several human societies have seen fit to worship corn, but perhaps it should be the other way around: For corn, we humans are the contingent beings. So far, this reckless-seeming act of evolutionary faith in us has been richly rewarded.

There are in fact no wild maize plants, and teosinte, the weedy grass from which corn is believed to have descended (the word is Nahuatl for “mother of corn”), has no ear, bears its handful of tiny naked seeds on a terminal rachis like most other grasses, and generally looks nothing whatsoever like maize. The current thinking among botanists is that several thousand years ago teosinte underwent an abrupt series of mutations that turned it into corn; geneticists calculate that changes on as few as four chromosomes could account for the main traits that distinguish teosinte from maize. Taken together, these mutations amounted to (in the words of botanist Hugh Iltis) a “catastrophic sexual transmutation”: the transfer of the plant’s female organs from the top of the grass to a monstrous sheathed ear in the middle of the stalk. The male organs stayed put, remaining in the tassel.

Each of the four hundred to eight hundred flowers on a cob has the potential to develop into a kernel—but only if a grain of pollen can find its way to its ovary, a task complicated by the distance the pollen has to travel and the intervening husk in which the cob is tightly wrapped. To surmount this last problem, each flower sends out through the tip of the husk a single, sticky strand of silk (technically its “style”) to snag its own grain of pollen. The silks emerge from the husk on the very day the tassel is set to shower its yellow dust. What happens next is very strange. After a grain of pollen has fallen through the air and alighted on the moistened tip of silk, its nucleus divides in two, creating a pair of twins, each with the same set of genes but a completely different role to perform in the creation of the kernel. The first twin’s job is to tunnel a microscopic tube down through the center of the silk thread. That accomplished, its clone slides down through the tunnel, past the husk, and into the waiting flower, a journey of between six and eight inches that takes several hours to complete. Upon arrival in the flower the second twin fuses with the egg to form the embryo—the germ of the future kernel. Then the first twin follows, entering the now fertilized flower, where it sets about forming the endosperm—the big, starchy part of the kernel. Every kernel of corn is the product of this intricate ménage à trois; the tiny, stunted kernels you often see at the narr...

One of every four Americans lived on a farm when Naylor’s grandfather arrived here in Churdan; his land and labor supplied enough food to feed his family and twelve other Americans besides. Less than a century after, fewer than 2 million Americans still farm—and they grow enough to feed the rest of us. What that means is that Naylor’s grandson, raising nothing but corn and soybeans on a fairly typical Iowa farm, is so astoundingly productive that he is, in effect, feeding some 129 Americans. Measured in terms of output per worker, American farmers like Naylor are the most productive humans who have ever lived.

the odds are good that at least one of the kernels grown on the Naylor farm has, like the proverbial atom from Caesar’s dying breath, made its way to me.

Today Churdan is virtually a ghost town, much of its main street shuttered. The barbershop, a food market, and the local movie theater have all closed in recent years; there’s a café and one sparsely stocked little market somehow still hanging on, but most people drive the ten miles to Jefferson to buy their groceries or pick up milk and eggs when they’re getting gas at the Kum & Go. The middle school can no longer field a baseball team or put together a band, it has so few students left, and it takes four local high schools to field a single football team: the Jefferson-Scranton-Paton-Churdan Rams. Just about the only going concern left standing in Churdan is the grain elevator, rising at the far end of town like a windowless concrete skyscraper. It endures because, people or no people, the corn keeps coming, more of it every year.

After the war the government had found itself with a tremendous surplus of ammonium nitrate, the principal ingredient in the making of explosives. Ammonium nitrate also happens to be an excellent source of nitrogen for plants. Serious thought was given to spraying America’s forests with the surplus chemical, to help out the timber industry. But agronomists in the Department of Agriculture had a better idea: Spread the ammonium nitrate on farmland as fertilizer. The chemical fertilizer industry (along with that of pesticides, which are based on poison gases developed for the war) is the product of the government’s effort to convert its war machine to peacetime purposes. As the Indian farmer activist Vandana Shiva says in her speeches, “We’re still eating the leftovers of World War II.”

The discovery of synthetic nitrogen changed everything—not just for the corn plant and the farm, not just for the food system, but also for the way life on earth is conducted. All life depends on nitrogen; it is the building block from which nature assembles amino acids, proteins, and nucleic acids; the genetic information that orders and perpetuates life is written in nitrogen ink. (This is why scientists speak of nitrogen as supplying life’s quality, while carbon provides the quantity.) But the supply of usable nitrogen on earth is limited. Although earth’s atmosphere is about 80 percent nitrogen, all those atoms are tightly paired, nonreactive, and therefore useless; the nineteenth-century chemist Justus von Liebig spoke of atmospheric nitrogen’s “indifference to all other substances.” To be of any value to plants and animals, these self-involved nitrogen atoms must be split and then joined to atoms of hydrogen. Chemists call this process of taking atoms from the atmosphere and combining them into molecules useful to living things “fixing” that element. Until a German Jewish chemist named Fritz Haber figured out how to turn this trick in 1909, all the usable nitrogen on earth had at one time been fixed by soil bacteria living on the roots of leguminous plants (such as peas or alfalfa or locust trees) or, less commonly, by the shock of electrical lightning, which can break nitrogen bonds in the air, releasing a light rain of fertility.

Before Fritz Haber’s invention the sheer amount of life earth could support—the size of crops and therefore the number of human bodies—was limited by the amount of nitrogen that bacteria and lightning could fix. By 1900, European scientists recognized that unless a way was found to augment this naturally occurring nitrogen, the growth of the human population would soon grind to a very painful halt. The same recognition by Chinese scientists a few decades later is probably what compelled China’s opening to the West: After Nixon’s 1972 trip the first major order the Chinese government placed was for thirteen massive fertilizer factories. Without them, China would probably have starved. This is why it may not be hyperbole to claim, as Smil does, that the Haber-Bosch process (Carl Bosch gets the credit for commercializing Haber’s idea) for fixing nitrogen is the most important invention of the twentieth century. He estimates that two of every five humans on earth today would not be alive if not for Fritz Haber’s invention. We can easily imagine a world without computers or electricity, Smil points out, but without synthetic fertilizer billions of people would never have been born.

But the reason for his obscurity has less to do with the importance of his work than the ugly twist of his biography, which recalls the dubious links between modern warfare and industrial agriculture. During World War I, Haber threw himself into the German war effort, and his chemistry kept alive Germany’s hopes for victory. After Britain choked off Germany’s supply of nitrates from Chilean mines, an essential ingredient in the manufacture of explosives, Haber’s technology allowed Germany to continue making bombs from synthetic nitrate. Later, as the war became mired in the trenches of France, Haber put his genius for chemistry to work developing poison gases—ammonia, then chlorine. (He subsequently developed Zyklon B, the gas used in Hitler’s concentration camps.) On April 22, 1915, Smil writes, Haber was “on the front lines directing the first gas attack in military history.” His “triumphant” return to Berlin was ruined a few days later when his wife, a fellow chemist sickened by her husband’s contribution to the war effort, used Haber’s army pistol to kill herself. Though Haber later converted to Christianity, his Jewish background forced him to flee Nazi Germany in the thirties; he died, broken, in a Basel hotel room in 1934. Perhaps because the history of science gets written by the victors, Fritz Haber’s story has been all but written out of the twentieth century. Not even a plaque marks the site of his great discovery at the University of Karlsruhe.

When humankind acquired the power to fix nitrogen, the basis of soil fertility shifted from a total reliance on the energy of the sun to a new reliance on fossil fuel. For the Haber-Bosch process works by combining nitrogen and hydrogen gases under immense heat and pressure in the presence of a catalyst. The heat and pressure are supplied by prodigious amounts of electricity, and the hydrogen is supplied by oil, coal, or, most commonly today, natural gas—fossil fuels. True, these fossil fuels were at one time billions of years ago created by the sun, but they are not renewable in the same way that the fertility created by a legume nourished by sunlight is. (That nitrogen is actually fixed by a bacterium living on the roots of the legume, which trades a tiny drip of sugar for the nitrogen the plant needs.)

When you add together the natural gas in the fertilizer to the fossil fuels it takes to make the pesticides, drive the tractors, and harvest, dry, and transport the corn, you find that every bushel of industrial corn requires the equivalent of between a quarter and a third of a gallon of oil to grow it—or around fifty gallons of oil per acre of corn. (Some estimates are much higher.) Put another way, it takes more than a calorie of fossil fuel energy to produce a calorie of food; before the advent of chemical fertilizer the Naylor farm produced more than two calories of food energy for every calorie of energy invested. From the standpoint of industrial efficiency, it’s too bad we can’t simply drink the petroleum directly.

More than half of the world’s supply of usable nitrogen is now man-made. (Unless you grew up on organic food, most of the kilo or so of nitrogen in your body was fixed by the Haber-Bosch process.)

The ultimate fate of the nitrates that George Naylor spreads on his cornfield in Iowa is to flow down the Mississippi into the Gulf of Mexico, where their deadly fertility poisons the marine ecosystem. The nitrogen tide stimulates the wild growth of algae, and the algae smother the fish, creating a “hypoxic,” or dead, zone as big as the state of New Jersey—and still growing.

This is more or less what New Deal farm programs attempted to do. For storable commodities such as corn, the government established a target price based on the cost of production, and whenever the market price dropped below that target, the farmer was given a choice. Instead of dumping corn onto a weak market (thereby weakening it further), the farmer could take out a loan from the government—using his crop as collateral—that allowed him to store his grain until prices recovered. At that point, he sold the corn and paid back the loan; if corn prices stayed low, he could elect to keep the money he’d borrowed and, in repayment, give the government his corn, which would then go into something that came to be called, rather quaintly, the “Ever-Normal Granary.”

Earl “Rusty” Butz, Richard Nixon’s second secretary of agriculture,

“The free market has never worked in agriculture and it never will. The economics of a family farm are very different than a firm’s: When prices fall, the firm can lay off people, idle factories, and make fewer widgets. Eventually the market finds a new balance between supply and demand. But the demand for food isn’t elastic; people don’t eat more just because food is cheap. And laying off farmers doesn’t help to reduce supply. You can fire me, but you can’t fire my land, because some other farmer who needs more cash flow or thinks he’s more efficient than I am will come in and farm it. Even if I go out of business this land will keep producing corn.”

But why corn and not something else? “We’re on the bottom rung of the industrial food chain here, using this land to produce energy and protein, mostly to feed animals. Corn is the most efficient way to produce energy, soybeans the most efficient way to produce protein.”

So the plague of cheap corn goes on, impoverishing farmers (both here and in the countries to which we export it), degrading the land, polluting the water, and bleeding the federal treasury, which now spends up to $5 billion a year subsidizing cheap corn. But though those subsidy checks go to the farmer (and represent nearly half of net farm income today), what the Treasury is really subsidizing are the buyers of all that cheap corn. “Agriculture’s always going to be organized by the government; the question is, organized for whose benefit? Now it’s for Cargill and Coca-Cola. It’s certainly not for the farmer.”

I was reminded of Thoreau’s line: “Men have become the tools of their tools.”

The agronomist’s reaction, like mine, owes something to our confusion of corn-the-food with corn-the-commodity, which turn out to be two subtly but crucially different things. What George Naylor grows, and what the pile by the elevator consists of, is “number 2 field corn,” an internationally recognized commodity grown everywhere (and nowhere in particular), fungible, traded in and speculated upon and accepted as a form of capital all over the world. And while number 2 field corn certainly looks like the corn you would eat, and is directly descended from the maize Friar Sahagún’s Aztecs worshipped as the source of life, it is less a food than an industrial raw material—and an abstraction. The kernels are hard to eat, but if you soak them in water for several hours you’ll find they taste less like corn than lightly corn-flavored starch.

Actually there are many different kinds of corn heaped together in this pile: George Naylor’s Pioneer Hi-Bred 34H31 mixed in with his neighbor Billy’s genetically modified 33P67; corn grown with atrazine mixed with corn grown with metolachlor. Number 2 corn is a lowest common denominator; all the designation tells you is that the moisture content of this corn is no more than 14 percent, and that fewer than 5 percent of the kernels exhibit insect damage. Other than that, this is the corn without qualities; quantity is really the only thing that counts.

The Iowa Farmers Cooperative does not write the only check George Naylor will receive for his corn crop this fall. He gets a second check from the U.S. Department of Agriculture (USDA)—about twenty-eight cents a bushel no matter what the market price of corn is, and considerably more should the price of corn drop below a certain threshold. Let’s say the price of a bushel falls to $1.45, as it most recently did in October 2005. Since the official target price (called the “loan rate”) in Greene County stands at $1.87, the government would then send farmers another $0.42 in “deficiency payments,” for a total of $0.70 for every bushel of corn they can grow. Taken together these federal payments account for nearly half the income of the average Iowa corn farmer and represent roughly a quarter of the $19 billion U.S. taxpayers spend each year on payments to farmers. This is a system designed to keep production high and prices low. In fact, it’s designed to drive prices ever lower, since handing farmers deficiency payments (as compared to the previous system of providing loans to support prices) encourages them to produce as much corn as they possibly can, and then to dump it all on the market no matter what the price—a practice that inevitably pushes prices even lower. And as prices decline, the only way a farmer like George Naylor can keep his income from declining is by producing still more corn. So the mountain grows, from 4 billion bushels in 1970 to 10 billion bushels today...

Ecology teaches that whenever an excess of organic matter arises anywhere in nature, creatures large and small inevitably step forward to consume it, sometimes creating whole new food chains in the process. In this case the creatures feasting on the surplus biomass are both metaphorical and real: There are the agribusiness corporations, foreign markets, and whole new industries (such as ethanol), and then there are the food scientists, livestock, and human eaters, as well as the usual array of microorganisms (such as E.coli O157:H7).

But Nature abhors a surplus, and the corn must be consumed. Enter the corn-fed American steer.

The economic logic of gathering so many animals together to feed them cheap corn in CAFOs is hard to argue with; it has made meat, which used to be a special occasion in most American homes, so cheap and abundant that many of us now eat it three times a day.

Raising animals on old-fashioned mixed farms such as the Naylors’ used to make simple biological sense: You can feed them the waste products of your crops, and you can feed their waste products to your crops.

For cows (like sheep, bison, and other ruminants) have evolved the special ability to convert grass—which single-stomached creatures like us can’t digest—into high-quality protein. They can do this because they possess what is surely the most highly evolved digestive organ in nature: the rumen. About the size of a medicine ball, the organ is essentially a twenty-gallon fermentation tank in which a resident population of bacteria dines on grass. Living their unseen lives at the far end of the food chain that culminates in a hamburger, these bacteria have, like the grasses, coevolved with the cow, whom they feed.

feeding large quantities of corn to cows for the greater part of their lives is a practice neither particularly old nor virtuous. Its chief advantage is that cows fed corn, a compact source of caloric energy, get fat quickly; their flesh also marbles well, giving it a taste and texture American consumers have come to like. Yet this corn-fed meat is demonstrably less healthy for us, since it contains more saturated fat and less omega-3 fatty acids than the meat of animals fed grass. A growing body of research suggests that many of the health problems associated with eating beef are really problems with corn-fed beef. (Modern-day hunter-gatherers who subsist on wild meat don’t have our rates of heart disease.) In the same way ruminants are ill adapted to eating corn, humans in turn may be poorly adapted to eating ruminants that eat corn.

Feather meal and chicken litter (that is, bedding, feces, and discarded bits of feed) are accepted cattle feeds,

Most of the antibiotics sold in America today end up in animal feed, a practice that, it is now generally acknowledged (except in agriculture), is leading directly to the evolution of new antibiotic-resistant superbugs.

Dr. Metzin complimented me on his size and conformation. “That’s a handsome-looking beef you got there.” (Shucks.)