Subway Restaurants announced it will eliminate artificial flavors, colors and preservatives from the menu over the next 18 months, such as caramel coloring. According to Nielsen, more than 40 percent of consumers view labels like "all natural" "no artificial colors" and "no artificial flavors" as very important when making purchasing decisions.

Subway's announcement follows other similar moves, like Panera Bread, which recently announced it would stop using artificial ingredients.

Elizabeth Stewart, Subway's director of corporate social responsibility, said converting Subway's large supply chain to all-natural would require "significantly more effort" than smaller chains. "But, we felt it was important to set an ambitious goal as a means to give us something to shoot for and demonstrate our unwavering commitment to wellness," Stewart said.