Food innovations these days tend to be fun, if unnecessary, improvements on proven winners. Flat pretzels, pre-peeled mini-carrots, and flash-frozen croissants are not exactly great leaps forward in the quest for human survival. The innovations that do fall into that category are far less flashy. Among them is the discovery in 1909 by the German-Jewish chemist Fritz Haber of how to “fix” nitrogen molecules. It led to death – in the form of explosives and poison gases used in World War II – and also to life, in the form of the first man-made fertilizer.

This revolutionary discovery altered drastically how humans grow and acquire food. It also contributed to the increasingly complex process by which dinner arrives on our plates. As that process becomes more elaborate, so does the disconnect between humans and the food we eat. This forms Michael Pollan’s point of departure in “The Omnivore’s Dilemma: A Natural History of Four Meals” (Penguin Press, 250 pages, $26.95).

“I realized the straightforward question ‘What should I eat?’ could no longer be answered without first addressing two other even more straightforward questions: ‘What am I eating? Where in the world did it come from?'” Mr. Pollan writes. Humans have evolved the ability and technology necessary to eat an unprecendented range of foods – the omnivore’s dilemma is figuring out which foods to choose. Nowadays, Mr. Pollan explains, these foods can come from four channels: industrial farming, large-scale organic farming, small-scale sustainable agriculture, and old-fashioned hunting and gathering.

Mr. Pollan explores the implication of these four channels with four meals. A McDonald’s cheeseburger lunch yields insights about agri-business and the life of the average American steer. Dinner made with organic ingredients from Whole Foods illustrates the battle between the USDA and the organic movement. A barbecued chicken from a small sustainable farm is the finale in Mr. Pollan’s education in how cows, chicken, grass, and sun can form a symbiotic system.

And braised wild pig, shot by Mr. Pollan himself, leads to a discourse on the humanity and guilt implicit in killing one’s own food.

These experiences lead him to unexpected and illuminating observations about our modern-day food chain. The adversary is the “supermarket pastoral,” the dreamy haze that separates Americans from the rather harsh realities of their food supply. Take corn: It turns out that nearly a quarter of the 45,000 items in the average American supermarket include corn – and we’re not just talking po lenta and cornbread. So how did corn become so ubiquitous? As Mr. Pollan explains, the rise of industrialized agriculture in the late 1940s led directly to vast fields of genetically identical plants. “Liberated from the old biological constraints, the farm could now be managed on industrial principles, as a factory transforming inputs of raw material – chemical fertilizer – into outputs of corn.”

Each year the federal government spends $19 billion to subsidize the growth of food like corn, thereby encouraging farmers to plant more, driving down corn’s already low cost. Meanwhile, food companies like ADM and Cargill – which not only buy and process the corn but supply the pesticides to grow it – reap the most benefit from state-sponsored low prices. Consequently, the abundance of cheap corn contributes to the obesity epidemic in the United States. “While the surgeon general is raising alarms over the epidemic of obesity, the president is signing farm bills designed to keep the river of cheap corn flowing, guaranteeing that the cheapest calories in the supermarket will continue to be the unhealthiest,” Mr. Pollan writes.

Where are the better options to be found? Health food stores might be the expected answer, but in this book, the wonders of organic produce undergo equal scrutiny. They may be better for the farmer, the environment, and the diner, but organic farms still rely on plenty of petroleum to cart the harvest cross-country to your local Whole Foods. “The trickiest contradiction Whole Foods attempts to reconcile is the one between the industrialization of the organic food industry of which it is a part and the pastoral ideals on which that industry has been built,” he writes. In Mr. Pollan’s view, if organic food means sustainable food, then the notion of an organic supermarket is probably contradictory.

The alternative to mass-market agriculture requires a pretty big paradigm shift, from the logic of capitalism to the logic of nature, from the large-scale to the small, from faceless corporations to individual farmers.That’s a lot to ask of Americans, but Mr. Pollan believes knowledge is the first step to changing the state of things. The glass-walled abattoir on Virginia’s small, sustainable Polyface Farm is one example of this. “The very option of looking – that transparency – is probably the best way to ensure that animals are killed in a manner that we can abide,” he writes. Mr. Pollan’s book could be considered an equally potent looking glass.

Though Mr. Pollan tackles plenty of tricky ground (and uses terms such as “military-industrial complex”), he is neither a pedant nor a proselytizer. Instead, he weaves facts, personal experience, and musings together into a truly gripping narrative.

Ms. Steiman writes regularly about food and cooking for The New York Sun.