A book telling us to “eat food” sounds about as necessary as one telling us to “breathe air”, “wear clothes” or “drink water”. Yet this is the main message of Michael Pollan’s In Defence of Food, his follow-up to The Omnivore’s Dilemma. What is more, he succeeds in making “eating food” seem entirely worthy of an apologia. For Pollan, the habit of “eating food” is, in fact, a radical departure from the prevailing norms of the western world.

It starts to make more sense when you see that much of what is consumed in modern America (and by implication in Britain, though Pollan seldom glances beyond the United States) does not count as food at all in his view. “For while it used to be that food was all you could eat, today there are thousands of other edible foodlike substances in the supermarket.” Pollan has in mind such products as Go-Gurt Portable Yogurt tubes; nondairy creamers; “breakfast cereal bars transacted by bright white veins representing, but in reality having nothing to do with, milk”; junky cereals; “cheeselike foodstuffs”; and “cakelike cylinders (with creamlike fillings)”, of which the notorious example is the Twinkie, an American “hostess cake” with a shelf life so long it almost never grows stale.

The true scandal of these quasi-foods, for Pollan, is that many of them are allowed to arrive with jumped-up health claims. No cholesterol! Low fat! Low salt! Far from being contested by the official nutrition advice of the government and medical establishment, the rise of the “edible foodlike substance” in the 1970s and 1980s was actually sanctioned by them. Pollan abhors what he calls “nutritionism”, the reduction of food to mere nutrients. From the 1970s onwards, when advising the population what to eat, American politicians learnt to speak of “nutrients” rather than specific foods, to avoid offending powerful food lobbyists. So instead of being told that it might be a good idea to cut back on the burgers and French fries, the American public was repeatedly told to eat less “fat”, advice that has now been more or less discredited (there are certain fats, notably those in oily fish, of which we should actually be eating more).

Consumers were lulled into a false sense of security. During the same era that they were being constantly encouraged to eat less fat, Americans got fatter and fatter. Instead of seeing that their diet was at fault (the refined flour, the paucity of fruit and vegetables, the excess of glucose and fructose syrups hidden in countless products), they kidded themselves they were eating healthily by switching to “low-fat” versions of their favourite junk. Pollan observes that the rise of “nutritionism” created an unprecedented marketing opportunity for the makers of highly processed foods, who could bring out “ever more novel” and profitable quasi-foods to satisfy the public’s desire for “nutrients”. Meanwhile, the genuinely wholesome foods (the plants, which as Pollan says, should form the bulk of what we eat) were getting sidelined. “As a general rule,” he writes, “it’s a whole lot easier to slap a health claim on a box of sugary cereal than on a raw potato or a carrot, with the perverse result that the most healthful foods in the supermarket sit there quietly . . . while a few aisles over in Cereal the Cocoa Puffs and Lucky Charms are screaming their newfound ‘whole-grain goodness’ to the rafters.”

Not much of this will come as news to anyone who has read Marion Nestle, the American nutritionist (and the author of Food Politics, 2003), whose work Pollan admits he has drawn on heavily. He also has a tendency to be too misty-eyed about the food of the past. “Don’t eat anything your great-grandmother wouldn’t recognise as food” is one of his maxims. What, so no extra virgin olive oil, no Thai curry, no sushi? Besides, our great-grandmothers had to suffer plenty of quasi-foods themselves, in the form of adulteration: floor sweepings disguised as pepper, pickles dyed green with copper.

However, Pollan’s prose at its best has a lyrical persuasion that compensates for the odd lapse of logic. He is particularly good on the joys and benefits of cooking. “When you cook at home,” he writes, “you seldom find yourself reaching for the ethoxylated dyglycerides or high-fructose corn syrup.” His final sentence brings home the real wonder of “eating food”: “The cook in the kitchen preparing a meal from plants and animals . . . has a great many things to worry about, but ‘health’ is simply not one of them because it is given.”

If you can't pronounce it, don't eat it

Sooner or later, everything solid we’ve been told about the links between diet and health gets blown away in the gust of the most recent study. In 2006, for example, we learnt that a low-fat diet, long believed to protect against cancer, does no such thing. Nor does it protect against heart disease. Or indeed, against obesity. In fact, just about everything nutritionist scientists have been preaching is wrong.

Pollan’s solution is simple: ignore the misleading lingo of “nutrients”, trans-fats, and omega oils . . . and think about food — real food — instead. Above all, avoid buying anything with ingredients that are a) unfamiliar b) unpronounceable c) more than five in number or d) include high-fructose corn syrup. Because they’re not food but “food products”.

IN DEFENCE OF FOOD by Michael Pollan
Allen Lane £16.99 pp256

Bee Wilson’s Swindled: From Poison Sweets to Counterfeit Coffee — The Dark History of the Food Cheats is published next week by J Murray

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