Be forewarned that you’re unlikely to look at the stuff on the shelves of your local supermarket in quite the same way ever again after watching Robert Kenner’s expose of the enormous power—and deleterious impact—of multinational corporations and agribusinesses in the production of food. Dissecting the effects on the products themselves, farmers and consumers—as well as how collusion between business and government has perpetuated and even worsened the system—“Food, Inc.” benefits from a coolly analytical approach that doesn’t ignore the human cost of what’s happening but appeals as much to the head as to the heart.

The film’s basic thrust is on the way in which private farmers have largely been driven out of agriculture by huge companies whose methods emphasize quantity over quality, leading to animals being kept in cramped buildings and force-fed, developing sicknesses that are then transmitted to consumers. (Several potent examples are provided through interviews with grieving survivors.) Emphasis is put on Monsanto, which has established a virtual monopoly on soybean production by patenting a chemical almost universally used in their production and then litigating against farmers who refuse to employ it. Another thread deals with the complicity of government, not only through revolving-door policies that put foxes, as it were, in charge of the hen-houses but maintain policies benefiting the agribusiness lobby, including subsidies on corn—the ultimate content of all sorts of products as well as a major source of animal feed—and special legal protection from prosecution.

Kenner has based his argument on the work of others, whom he not only acknowledges but includes as interviewees. The most notable are Eric Schlosser, whose “Fast Food Nation” was turned into a mediocre fiction film by Richard Linklater, and Michael Pollan, author of “The Omnivore’s Dilemma.” But he also includes sequences in which farmers who resist pressure from the likes of Monsanto describe their experiences, as well as a few employed by big companies are willing to talk despite legal restrictions placed on them by those firms. There’s also Joel Salatin, a true believer who operates a small place in Virginia where he raises pigs and chickens the old-fashioned way while growing vegetables organically. He excoriates current practice and argues strongly, if a bit petulantly, for the alternative he represents.

“Food, Inc.” probably won’t be seen by many consumers, but it deserves to be. It would help teach them that there are choices other than tasteless tomatoes and soggy fast-food burgers, and impress on them that the government should be prodded to represent the interests of consumers rather than corporations—especially when the kinds of food they produce and market contributes so greatly to the epidemic of obesity that’s recognized as one of the major health problems facing the country today. After all, public awareness eventually played a role in dealing with Big Tobacco. It could do so in confronting the dangers posed by Big Food, too.