Kai Robertson, the author of the study and a food marketing expert, found no evidence linking changes in food labels to supermarket prices. A number of other factors impact pricing at supermarkets such as the demographics of shoppers, what prices competitors are offering and the specific market where the store is located, she said.
"As with supermarkets, a food processor’s overall costs (and therefore prices charged to retailers) are affected by a wide range of variables, most significantly the cost of ingredients and energy prices, as well as manufacturing, packaging, and marketing expenses," wrote Robertson, who used to work for the Food Marketing Institute, the trade organization representing supermarkets. "Label changes are but one of a myriad of necessary and voluntary variables that affects a manufacturer’s costs and therefore prices."
The study was released amid continuing debate over whether food manufacturers should have to disclose the presence of GMOs on labels.
About half the U.S. states have introduced legislation or ballot initiatives that would require GMO labeling. Federal law imposes no such requirement, although some members of Congress have introduced legislation that would require labels for genetically engineered whole and processed foods.
Robertson said food manufacturers often change their labels for reasons that relate to marketing and regulations.
Such changes have a negligible impact on costs, said Jerry Greenfield, co-founder of Ben & Jerry's, which intends to source ingredients by next year that are entirely free of GMOs.
"The impact on the cost just to put something on your label is essentially zero," he said today during a conference call with media that was arranged by Just Label It, the organization that released Robertson's study.
Heather Garlich, a spokeswoman for the Food Marketing Institute, agreed that many factors influence food prices, such as agricultural conditions and operating costs.
"Regarding operating costs, given the retailer's razor-thin profit margin, even the smallest change could impact the price of food," she said in an emailed statement.
A representatives of the Grocery Manufacturers Association did not respond today to a request for comment on the study.
Citing economic studies, a campaign against California's 2012 GMO labeling ballot initiative—Prop 37—maintained the measure would cost the average California family up to $400 per year in increased grocery costs. The measure was defeated in November.