At the Natural Grocery Co. in Berkeley, Calif., green shelf tags highlight “non-GMO” verified products, while those products “at risk” of containing genetically modified organisms, or GMOs, are flagged with a damning red sticker.

At Nature’s Pantry, in Kansas City, Mo., prominent displays showcase books and DVDs on the perils of genetic engineering.

At Mile High Organics, two full-time staffers spend their days scrutinizing products to assure they fulfill the company promise of being “Colorado’s only completely non-GMO retailer.”

 “Consumers have about 6 seconds to make product decisions in grocery aisles with thousands of options,” says Mile High Organics Founder Michael Joseph, of Denver. “I believe retailers have an obligation to help them address the issue of GMOs.”

Seventeen years after genetically engineered (GE) food hit the shelves, retailers from coast to coast are doing just that, joining an unprecedented and—and many say—long overdue groundswell to slow the march of GE crops across America’s farmlands and tables.

Today, GE crops (particularly corn, soy, canola and cotton) make up half of all land harvested in the United States; GMOs are present in roughly 80 percent of processed foods. Just six years after the approval of GMO sugar beets, genetically modified sugar makes up half the nation’s sugar supply, according to biotech giant Monsanto. With the January 2011 approval of GM alfalfa (often used for animal feed), and the pending approval of GM Salmon, dairy products and meat are poised to be the next so-called “Frankenfoods.”

Such swift proliferation, along with recent studies showing clear and present environmental impacts of GMOs, have galvanized purveyors and consumers of natural products, spawning everything from theatrical protests to sophisticated lobbying efforts. Many fear we could someday lose our ability to choose genetically unadulterated products—if we haven’t already.

“We have failed as an industry to build a powerful coalition around this issue and now we are in real jeopardy,” says Stonyfield Farm CEO Gary Hirshberg, who spends “90 percent” of his time speaking to stakeholders about GMOs. “Now is the time to act.”

But just what that action should look like—and the role natural products retailers should play—is a matter of great, sometimes ferocious, debate.