IS THE global fad for quinoa a bane or boon to the peasants of the Andes? For centuries they were more or less the only people to grow or eat the stuff. Dieticians in the rich world have known how nutritious it is for a long time: in 1993 a study by NASA, America’s space agency, stated: “While no single food can supply all the essential life-sustaining nutrients, quinoa comes as close as any other in the plant or animal kingdom.” But it took adulation from the likes of Oprah Winfrey (who in 2008 included it in her 21-day “cleanse” diet) to give the grain global appeal. Now, wherever yuppies can be found, it can be too, usually lurking near Puy lentils or goji berries in a salad. The UN even branded 2013 the International Year of Quinoa.

As demand galloped ahead, supply could not keep pace. So between 2000 and its peak in 2014, the average price of quinoa exports from Peru and Bolivia more than tripled, to $6-7 a kilogram. That panicked the Guardian, a British newspaper, among other hand-wringers: in 2013 it ran the headline “Can vegans stomach the unpalatable truth about quinoa?” It accused heedless Western hipsters of pricing poor Andeans out of their staple food. Given that 16% of Bolivians and 7.5% of Peruvians are undernourished, according to the UN, that is a serious charge.

Happily, the food fadsters are not guilty. Although average quinoa consumption in Peru fell as quinoa prices rose, it did so steadily, and much less abruptly, than the movement in the price. This suggests that the switch was as much to do with changing preferences as prices. Young Peruvians are keener to indulge in food fads of their own—for more Western food—than to gorge on their grandparents’ staple.

Not so keen on quinoa

In any case, only a tiny portion of Peruvian household spending is devoted to quinoa. In countries like Bangladesh, Malawi and Vietnam, sharp increases in the price of staple foods can plunge the poor into even deeper poverty, as they often spend more than a third of their income on them. But a study by Andrew Stevens at the University of California found that quinoa accounted for a mere 0.5% of household spending, on average.

For farmers, meanwhile, higher prices meant higher incomes. Peruvian and Bolivian quinoa-growers need all the money they can get. Before the boom, many were barely scraping by. Another study, published in March, found that the total household spending of the typical quinoa-growing family (including consumption of their own crop) was only 40% of that of the typical quinoa-consuming family.

Surging prices helped lift quinoa farmers’ household expenditure by 46% between 2004 and 2013 (compared with an increase of around 30% for non-producing households). Better still, even households that did not produce quinoa enjoyed a boost to their consumption. It seems that by spending their newfound income, flush quinoa producers benefited the local economy more broadly. For every 25% increase in the price, household consumption increased by 1.75%.

Although concerns for the poorest Peruvians were misplaced in 2013, there may be cause to worry now. The high prices of 2013-14 prompted many more people to start growing quinoa, from entrepreneurial Bolivian taxi drivers to large agribusinesses. European farmers got in on the act, too. Quinoa is now grown in around 50 countries, according to James Livingstone-Wallace, founder of Quinola, a quinoa supplier.

That means a lot more supply: the combined volume of quinoa exports from Peru and Bolivia to the European Union rose by 227% between 2012 and 2015. Prices, naturally, have plummeted—by 40% between September 2014 and August 2015 alone. Following that drop, wages in the two regions that had traditionally produced the most quinoa fell by 5%, and total food consumption by 10%, according to a new report from the International Trade Centre, a development agency.

The same study suggests that many Andean farmers are hoarding quinoa, in the hope that prices will rise again. But European farmers are doing the same, according to Freek Jan Koekoek, a consultant. In other words, there is a real chance that prices could fall further, as farmers despair and sell their stocks.

If that happens, the marginal producers likely to be pushed out of business by the glut are the original ones: poor Andean farmers. They grow quinoa because little else thrives on their steep, barren plots. Their new competitors, tilling better soil with modern farming equipment, manage yields that are up to eight times higher. An ox takes six days to plough land a tractor can handle in two hours, explains Mr Livingstone-Wallace. “With their current methods, it’s unlikely they’ll be able to compete on price,” he says.

The “Fairtrade” price of quinoa (which is meant to correspond to the minimum required to give farmers a decent standard of living) is around $2.60 a kilo; the current market rate is less than $2, suggesting that Andean growers are already struggling. The idea that the Andes might cease to be the world’s main source of quinoa is not far-fetched. The potato, after all, originated there, but now 15 other countries, including Bangladesh and Belarus, produce more potatoes than Peru does.

Yet Peru still produces around 4,000 varieties of potato, which foodies are trying to brand and market to Western consumers. The main hope of Andean producers is to carve out a niche in the market with their authentic, organic, “heirloom” quinoa, appealing to the same consumers who were warned away back in 2013.