In Defense of Food: An Eater’s Manifesto? A churlish title, perhaps—but these days it’s hard not to agree with Michael Pollan that all eating is a political act.

And maybe we should add, with the start of another presidential season upon us, that politics is just a continuation of food by other means. Because whatever the verdict of future historians on the strange meta-ritual called the Iowa caucuses, its most deleterious effect—in 2008, as in 2004 and 2000 and 1972—is already solidified in the latest U.S. Farm Bill.

Yes, it’s true: The lone superpower so routinely excoriated for its neoliberal, free-trade orthodoxy turns out to support rather gladly protectionist subsidies for peasants—so long as said peasants own their own homes, are concerned about retirement savings and show up in church basements in Sioux City, Iowa, on a certain January night eager to vote for, well, nothing so much in particular (it’s not really a primary, after all) as the continued misery of peasants in Somalia, Indonesia, Brazil et al.

I’ve probably never actually tasted cane sugar from Ecuador, but I’m sure it can’t be worse than the corn syrup from Ames, so cheap at the soda machine because you’ve in fact been financing that glucose rush since it was a jumble of chromatids in a Monsanto lab.

Well, anything to save the American farm!

THE COROLLARIES (AND coronaries) of America’s pathological agricultural policies have generated a new creative genre aimed at a postmodern phenomenology of food, a national ontology of obesity. Eric Schlosser’s Fast Food Nation (2001) had the vitriol and self-importance of Upton Sinclair’s The Jungle (1906), though sadly not yet the impact, and Morgan Spurlock’s recent film Super Size Me must be admired as an historical artifact, if only because its release marked the final victory of performance art and gross-out comedy over political protest.

Pop historians have been in on the act as well—see Mark Kurlansky’s triptych on cod, salt and oysters, persuasive proof that we were always what we ate, even when it wasn’t genetically modified and partially hydrogenated.

The best of this new genre is The Omnivore’s Dilemma (2006), Michael Pollan’s literary masterwork. Yes, literary, and yes, masterwork: To read Mr. Pollan’s enchanting chapter on chanterelle-hunting in Northern California is to entertain the possibility that journalists and mushrooms have souls after all.

The genius of The Omnivore’s Dilemma—like that of many foodstuffs—lies in its vigorous hybridity; its passages tracing the provenance, political and corporeal, of the cheap McDonald’s hamburger do as much whistle-blowing as Messrs. Schlosser and Spurlock, but they’re wedded to the concerns of another movement: namely, the ethical hedonism proposed by the neo-gourmands of slow-food and molecular gastronomy and organic everything.

There’s a tension here: Arguing that corporations and the government are killing us with food policy is not quite the same as saying you can save yourself—and enjoy yourself—by joining a local farmers’ collective. In fact, if you do one, you should probably eschew the other.

In The Omnivore’s Dilemma, Mr. Pollan’s brilliance was in exploiting the power of this tension even as he tried to smooth it over. That the book’s narrator is in many ways so resolutely unlikable—Mr. Pollan has no qualms presenting himself as the kind of Berkeley liberal who can spending many happy hours in the kitchen and at the farmer’s market, and devote weeks of leisure time to searching for the perfect (nonpsychotropic) fungi—makes the visceral rightness of what he’s saying all the more impressive. You can’t choose your prophets, and Mr. Pollan’s pearlescent prose weighs as heavily on the emaciated militant as on the simple glutton.

With In Defense of Food, a slim volume best read as the author’s own gloss on the lessons of The Omnivore’s Dilemma, Mr. Pollan replaces magisterial reportage with direct argument. A manifesto, indeed: What it makes manifest is the intractability of those Berkeley contradictions so beautifully suspended in the earlier text.

It turns out that Mr. Pollan has been about self-help all long: In Defense of Food’s recurring refrain is “Eat food [i.e., real food, not the supermarket and fast-food staples associated with the poor and fat]. Not too much [that is, in ‘European’ amounts]. Mostly plants [fresh, unprocessed ones].”

The enemy in this manifesto is “nutritionism,” which Mr. Pollan regards as an ideology—an ideology that aims to atomize delicious, sensuous foods into their component nutrient contents. Which can’t help but smell ridiculous. Sure, the nutritionist culture of food pyramids and Atkins and omega-6 fetishism is unfortunate, but is the scientific investigation into the metabolic actions of proteins, lipids, carbohydrates, vitamins and minerals really to blame for our food troubles? At its shrillest, Mr. Pollan’s alarmism regarding additives or “supplementation” of any sort uncomfortably recall those superstitious third-world leaders who deny their populations iodized salt.

But don’t get the wrong idea; for the most part, this “eater’s manifesto” is blithely unconcerned with the means of production--not when there’s preparation to talk about. Indeed, when he turns his attention to the Nixon-era policy changes that led to our current flood of cheap, empty, subsidized calories, Mr. Pollan seems less inclined to call for collective action than unilateral disarmament: “My guess … is that paying more for food will reduce the amount of it we eat.” He’s probably right that in a population that has recently discovered the money and time for cell phones and Internet use, many of us could spend more on food each week. But any bottom-up structural change would hinge on millions of individuals deciding, against all basic economic and biological rationale, that taste trumps industrial affordability and convenience. Which gets at the central problem: Few human beings share Mr. Pollan’s existential reverence for food.

That doesn’t mean we shouldn’t be eating better; and it doesn’t mean that the global food supply isn’t scandalously broken. Forgetting, for a moment, Mr. Pollan’s intended audience of heirloom gardeners and cuisinistas, if everyone on the planet suddenly decided to eat the way he does, no small number would starve within weeks. Which is another way of saying we won’t ever all eat the way Michael Pollan does, that industrialization can’t be undone, that sustained sustenance is not just a matter of reawakening the culinary “aborigine in all of us” and “escaping from the Western diet.”

If The Omnivore’s Dilemma suggested a synthesis of head and gut, In Defense of Food leaves you with the taste of numb truth: The vanguard in any food revolution won’t be the ones with cultivated palates.

Jonathan Liu is a writer living in Queens.