Opponents of genetically modified foods celebrated a new study this week that found pigs fed genetically modified grains were less healthy than pigs on a non-GMO diet. The team of Australian scientists and U.S. researchers divided 168 pigs into two groups: one fed a diet of genetically modified corn and soy; the other fed non-GMO grain. Over the span of 22.7 weeks, the pigs fed the genetically altered feed showed higher stomach inflammation.

“This pig study is the first really sound study that has shown that there may be some damage to mammals, and pigs are very close structurally to humans, as a result of eating genetically modified foods,” says Mark Bittman, a food writer and columnist at The New York Times and author of the new book "VB6."

Bittman, who supported California’s ballot initiative last fall to label foods with genetically modified ingredients, says “we have a long way to go before we demonstrate that it’s unhealthy for us to eat foods that contain” GMOs. But the push for label transparency “is not a radical, screwball commi-plot,” he argues in the attached video. “This is a normal way of life in much of the world.”

Related: Michael Pollan: Genetically Modified Foods Offer Consumers "Nothing"

Sixty-four countries either ban genetically engineered foods or require GMO labeling; the U.S. and Canada have no restrictions on GMO products. The most common foods that are genetically modified include corn, soy, cotton, papaya, alfalfa, sugar beets and canola. About 75 to 80 percent of U.S. processed foods contain GMO seeds, according to the Grocery Manufacturers Association.

Related: Whole Foods CEO: If Syria Has GMO-Regulations, So Should the U.S.

Hugh Grant, CEO of Monsanto, told Bloomberg in an interview this May that the anti-GMO movement has become a “strange kind of reverse elitism: If I’m going to do this, then everything else shouldn’t exist. There is space in the supermarket shelf for all of us.”

Monsanto (MON) is the largest producer of GMO seeds and has spent millions of dollars fighting labeling legislation. Over Memorial Day weekend the “March Against Monsanto” protest attracted hundreds of thousands of people in 52 countries and 436 cities. The U.S. Department of Agriculture ruled last month that it needs more time to conduct detailed studies of new genetically modified corn, soybean and cotton seeds from Monsanto and Dow Chemical Co. (DOW) before approving their use in the food supply.

These seeds "may significantly affect the quality of the human environment,” the USDA said in a statement.