If you like quinoa, asparagus, or free trade, read this.

Back in 2007-08, those of us engaged in the Obama-Edwards-Clinton debates on this site couldn't shut up about the difference between the candidates on the Peruvian Free Trade Agreement, though that agreement was largely about their duties on importing our goods. Peru's ability to ship agricultural goods here duty-free was established by prior Andean trade preference agreements designed to encourage farmers to grow something other than coca.

And it's worked. Perhaps, too well, as the Guardian (UK) reported yesterday:

Not long ago, quinoa was just an obscure Peruvian grain you could only buy in wholefood shops. ... Sales took off. Quinoa was, in marketing speak, the "miracle grain of the Andes", a healthy, right-on, ethical addition to the meat avoider's larder (no dead animals, just a crop that doesn't feel pain). Consequently, the price shot up ' it has tripled since 2006 ' with more rarified black, red and "royal" types commanding particularly handsome premiums.

But there is an unpalatable truth to face for those of us with a bag of quinoa in the larder. The appetite of countries such as ours for this grain has pushed up prices to such an extent that poorer people in Peru and Bolivia, for whom it was once a nourishing staple food, can no longer afford to eat it. Imported junk food is cheaper. In Lima, quinoa now costs more than chicken. Outside the cities, and fuelled by overseas demand, the pressure is on to turn land that once produced a portfolio of diverse crops into quinoa monoculture.

In fact, the quinoa trade is yet another troubling example of a damaging north-south exchange, with well-intentioned health and ethics-led consumers here unwittingly driving poverty there. It's beginning to look like a cautionary tale of how a focus on exporting premium foods can damage the producer country's food security. Feeding our apparently insatiable 365-day-a-year hunger for this luxury vegetable, Peru has also cornered the world market in asparagus. Result? In the arid Ica region where Peruvian asparagus production is concentrated, this thirsty export vegetable has depleted the water resources on which local people depend. NGOs report that asparagus labourers toil in sub-standard conditions and cannot afford to feed their children while fat cat exporters and foreign supermarkets cream off the profits. That's the pedigree of all those bunches of pricy spears on supermarket shelves.

(Continue reading below the fold.)