But some fear that too many details could result in information overload, as menus become increasingly cluttered. Eateries such as Otarian in New York and Max in Stockholm now list the carbon dioxide emissions associated with producing and transporting their food. Other menus point out ingredients produced using biodynamic agriculture, a form of organic farming.
Restaurant chains said there was only so much they could do to steer customers from potentially troublesome ingredients. Besides, some companies with secret formulas and proprietary recipes are hesitant to publicize complete ingredient lists.
Still, some chains such as Wendy's are positioning themselves to be at the forefront of the trend. Besides offering a gluten-free menu, it has nutritional posters listing all ingredients and potential allergens, such as peanut oil.
On its website, Wendy's also has more specific warnings for some items, such as one that cautions patrons with dairy allergies to ask for alternatives to the chain's new butter-toasted buns. But the company can't design meals for those with specific diets.
"We have to develop products for the mass audience," spokesman Denny Lynch said. "We don't have the luxury of being able to create specific, targeted products to one group."