The fast-food chain had claimed that its fries were safe for those who have dietary issues with gluten, milk or wheat.
However, this month, McDonald's added "Contains wheat and milk ingredients," in reference to the french fries on its Web site, reports The Associated Press.
The company said it made the change because of new regulations for the packaged food industry by the U.S. Food and Drug Administration.
One of the rules requires that the presence of common allergens such as milk, eggs, peanuts, fish or wheat, must be reported.
McDonald's says it is a restaurant operator, so it technically does not have to comply. But it says it is doing so voluntary, reports the AP.
The company's potato suppliers remove all wheat and dairy proteins that can cause allergic reactions, but the flavoring agent in the cooking oil is a derivative of wheat and dairy, says McDonald's director of global nutrition, Cathy Kapica.
"We knew there were always wheat and dairy derivatives in there, but they were not the protein component," she said. "Technically there are no allergens in there. What this is an example of is science evolving" and McDonald's responding as more is learned, she said.
