If you are what you eat, then the thoughtful documentary "Food, Inc." reports that we are unhealthy, prone to disease, and supporting companies that guard their secrecy as they do horrible things to their employees and their products, as well as the planet.

Director Robert Kenner, a veteran of PBS' "The American Experience" series, takes us on a survey of the American food-production industry, from the farm to the plate, and finds trouble at every step.

For starters, saying "farm" is a misnomer these days, because so much of our commodity crops -- corn, wheat, soybeans, beef, pigs and chicken -- are mass-produced with assembly-line techniques that more resemble factories than the bucolic farms on the product labels. Kenner finds animal-processing facilities where genetically overbred livestock are fed antibiotic-filled corn feed and trotted through their own fecal material on the way to the slaughterhouse.

Meanwhile, federal subsidies have made corn so cheap to grow that it shows up everywhere, from Coca-Cola to batteries. The artificially low cost of such crops also means it's cheaper to buy a greasy drive-thru cheeseburger than a head of broccoli -- thus fueling the nation's obesity epidemic, particularly in lower-income communities.

But heaven help you if you run afoul of the conglomerates that make your food. Many meatpacking companies, the movie claims, treat their employees -- some of whom are undocumented migrants from Mexico -- as poorly as their animals. Firms like Monsanto sell genetically modified soybean seed, then ruthlessly patrol and prosecute farmers (even ones who never bought or wanted Monsanto products) who save seed for next year's crop. "Veggie libel" laws in 13 states take away your free-speech rights if you disparage a food product, and only Oprah can afford the lawyers to fight back in court.

It's all good information to have on hand, and Kenner puts it together in a bright and breezy narrative. He interviews food advocates who warn of the problems posed, as well as a few mavericks -- such as natural farmer Joel Salatin, or Gary Hirshberg, the founder of the organic yogurt makers Stonyfield Farms -- trying to make a difference. And it's not a complete anti-corporate screed, as evidenced by the fact that it finds something nice to say about, of all companies, WalMart.

For anyone who's been paying attention in the past few years, there's not a lot here you didn't know already -- especially if you've read Eric Schlosser's Fast Food Nation or Michael Pollan's The Omnivore's Dilemma (Schlosser and Pollan are interviewed here). But as a primer for those just encountering the issue, "Food, Inc." is definitely food for thought.

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