For related articles and information, please visit OCA’s Genetic Engineering page and our Millions Against Monsanto.

Two years ago, Ben & Jerry’s Homemade Inc. initiated a plan to eliminate genetically modified ingredients from its ice cream, an effort to address a nascent consumer backlash and to fulfill its own environmental goals.

This fall, nearly a year behind schedule, it expects to finish phase one, affecting its flavorful “chunks and swirls” like cookie dough and caramel. The only part left to convert: the milk that makes ice cream itself. Thanks to the complexities of sourcing milk deemed free of genetically modified material, that could take five to 10 more years.

“There’s a lot more that goes into it than people realize,” said Rob Michalak, Ben & Jerry’s director of social mission.

Two decades after the first genetically engineered seeds were sold commercially in the U.S., genetically modified organisms-the crops grown from such seeds-are the norm in the American diet, used to make ingredients in about 80% of packaged food, according to industry estimates. (Take a quiz about GMOs.)

Now an intensifying campaign, spearheaded by consumer and environmental advocacy groups like Green America, is causing a small but growing number of mainstream food makers to jettison genetically modified organisms, or GMOs. In addition to Ben & Jerry’s, a subsidiary of Unilever PLC, General Mills Inc. this year started selling its original flavor Cheerios without GMOs. Post Holdings Inc. took the GMOs out of Grape-Nuts. Boulder Brands Inc.’s Smart Balance has converted to non-GMO for its line of margarine and other spreads. Chipotle Mexican Grill Inc. is switching to non-GMO corn tortillas.