In 1999, when the French peasant leader Jos? Bov? trashed a McDonald's under construction near Montpellier, so becoming a national and, soon, international resistance hero, one motive for his virtuous vandalism was cheese. The Americans had unilaterally imposed trade restrictions on the excellent local Roquefort, and, if there was going to be no Roquefort in the US, there was no reason to tolerate the "McMerde" double bacon cheeseburger in France.

American multinational muck was malbouffe: bad to eat, bad for the peasant farmers in la France profonde who produced the proper stuff, bad for France. The sentiment was popular, and that's why Bov? spent only six weeks in jail, and why Lionel Jospin called his action "just": the defence of fine French food against American anti-cuisine was recognised as a moral act.

Invited by Ralph Nader later that year to the demonstrations against the World Trade Organisation in Seattle, Bov? underlined the point, smuggling some unpasteurised Roquefort past American customs officers and posing for the cameras eating a Roquefort sandwich in front of a local McDonald's, which was duly vandalised in its turn. "You are what you eat," Bov? said, "where you live and what you do. We are peasants and citizens, not shareholders, not servile slaves at the mercy of agribusiness." The peasant-shepherd - the Ast?rixian champion of local food - has become world-famous, and you can download his dicta in defence of localism from that least local of media, the world wide web.

So here's a way into the tensions and paradoxes of the way we eat now: globalised food has secured its spread across the dietary landscape by managing two tricks at once. First, as it has become globalised, so it has become homogenised: it is the same everywhere, or, more accurately, widely believed to be the same everywhere. The natural home for a McDonald's is the international airport lounge, and the Economist can find no better way of assessing the real value of world currencies than comparing the local price of a Big Mac against a US standard.

... the homogeneity of the globalised product is necessarily a relative matter, and belief in its stability may not be supported in reality. Though it is evidently a great secret, I'm told that McDonald's buns have a lot more sugar in Britain than they do in the States; there is, of course, no beef (Hindu sensibilities) or pork (Muslim) in the Indian "Maharaja Mac"; the mayonnaise has no egg in it (for vegans); and, when Bov? did his splendid work on the Montpellier McDonald's, the local company representative was at tactical pains to stress difference, assuring the demonstrators that the burgers were an authentically local product, containing only French beef "from the farm".

Second, globalised products such as the Big Mac and Coke have secured their spread across the world by travelling in the special channels carved out by American power, capital and culture. While Big Macs are now everywhere - you can avoid them in Bhutan and Afghanistan, but that's a high price to pay - it would be impossible to explain their global distribution without attending to those channels and to their identification with the powerful idea of America. Just as Ch?teau Lynch-Bages has a Pauillac Appellation d'Origine Contr?l?e, so the Big Mac is AOC USA. You can't account for why so many people throughout the world want to eat it - or, indeed, why so many others use it as a reference for globalised abominations - without understanding their ideas about the place called America.

In these respects Camembert is a lot more like the McMerde burger than you might suppose. ...