Most people aren’t overly concerned about what they eat. If it tastes good, they’ll eat it, with little thought given to how that meal reaches their plates.

Food Inc. is an expose of the business behind the food industry and explores where food comes from (at least in the American market) and what we’re not told about its manufacture.

If you’re an American, the next time you eat beef, it’s probably from a cow that spent most of its life standing ankle-deep in its own manure.

It doesn’t matter if you’re in MacDonald’s or a posh steak house as most of the meat in America is produced by four major corporations.

Chickens now move from egg to death in six weeks and grow to twice the size they were 50 years ago in half the time. They’re kept in perpetual darkness and so badly looked after that they can’t even stand.

But it’s not just the inherent cruelty to livestock that Food Inc. is intent on uncovering; it’s the secrecy and manipulation of the corporations behind the food we eat. It’s not just about what we’re not allowed to know, it’s also about what we’re not allowed to say.

Chicken farmer Carole Morrison lets us see inside her chicken houses. Consequently a chicken processor cancelled her contract – something that anyone who has to make a living fears. The message is clear – tell anyone what you get up to and we’ll drive you out of business.

But large companies hold the reins when it comes to business. Huge multinational Monsanto holds a patent for giant soybeans which are aggressively sold to farmers for their increased yields.

But Monsanto forbids the saving of seeds for planting next year – betraying a very basic farming practice and forcing farmers to buy new seed next year. If you try to rebel, you’re sued into the ground; farmers are held in thrall to large corporations much like drug addicts are to their pushers.

The documentary makes some concessions –– it shows how a poor family save time and money by eating fast food – what incentive do they have to eat good food when mass produced stuff is so cheap and plentiful?

But with eight per cent of the American population having type two diabetes, what they save on food, they’ll repay in medical bills.

It’s not all doom and gloom. Food Inc. offers some hope. Supermarket behemoth Wal-Mart signed up with eco-conscious Stonyfield Farms due to the pressures of consumer demand – if there’s something we can do about it, it’s by voting with our purchases.

This is the film that Eric Schlosser’s book Fast Food Nation should have been (not the watered down Richard Linklater film which tried to impose a narrative on the bare facts) – a reasoned and persuasive documentary that will force anyone who watches it to think about where their food comes from.

Food, Inc (PG) is in cinemas now.