When bread goes stale, it hardens, unlike chips, which become soft. Khuroshvili Ilya/Flickr McDonald's is by no means the most accommodating of fast-food chains to people with special dietary requirements. Many of its restaurants in America and Britain do not even serve a meat-free burger for vegetarians. But in a week-long trial ending on October 21st, the chain’s British outlets offered a new burger whose fillings did not contain gluten, an allergen commonly found in wheat, with a view to making the new product a permanent addition to its menu.



At first, that may seem to be an odd decision. Vegetarians outnumber those who avoid gluten. But the food industry is finding that there is no longer much money to be made in making meat-free products. Sales of alternatives to meat have flattened in America in real terms since 2008; in Britain they have plunged by a third.

Consumer demand for products without gluten, however, is rising rapidly. Health-conscious Americans were first to avoid it in significant numbers. Sales of gluten-free food and drink there have surged from $5.4 billion to $8.8 billion over the past two years, according to Mintel, a market-research firm. They are set to grow a further 20% by 2015.

Europe is now quickly catching up: there is double-digit sales growth in most countries, with Britain leading the way. This makes for tasty business. Sales in America of food untainted by gluten are forecast to grow by a further 61% by 2017, with similar increases expected in other rich countries.

Udis gluten-free suite at Sundance. Gustavo Caballero/Getty Images for Udi's Gluten Free Shops have reshuffled their shelves and restaurants rewritten their menus to keep up with demand. Big supermarkets have been slimming down their range of vegetarian products and are stocking more gluten-free lines. Even small convenience stores in remote parts of rural Ireland and Italy now stock ranges of gluten-free bread and cakes.

Restaurants, in particular, have rushed to launch menus that banish the stuff. The number of options that leave out gluten in British restaurants has tripled since 2011, says Emma Read at Horizons, a data firm. That is less because restaurateurs fear losing bookings from diners who want to avoid gluten, but more that they worry that their family and friends will not come along either.

Yet some retail analysts fret that the wheat-free bubble will eventually burst, as it already has for meat substitutes. Many doctors say that only a few of the one-in-ten households that now regularly buy such products have a member with coeliac disease and a medical need to avoid gluten.

But research from Monash University published last year shows that many more people may be sensitive to other allergens that are found in wheat. And according to a survey by Kantar, a research firm, only 22% of people who buy gluten-free food say they do so for non-medical reasons. This could be one foodie trend that turns out to be much more than a fad.