It’s easy for the average consumer to assume that food labeled “natural” is healthy, wholesome, and free of genetically modified organisms (GMOs). After all, the dictionary definition of the word natural is “existing in, or formed by, nature as opposed to artificial.

But, more often than not, according to a Consumer Reports study released today, processed foods with a “natural” label actually contain significant amounts of GMOs.

The majority of people remain understandably confused about the ingredients in foods labeled “natural.” According to the Consumer Reports National Research Center, out of a sample of 1,000 American adults, 64 percent believed that “natural” was synonymous with GMO-free.

As a result, Urvashi Rangan, Ph.D., who directs Consumer Reports’ food safety and sustainability work, has called for a ban on the “natural” label in food, saying that it misleads consumers.

Despite the big interest in GMO labeling amongst American consumers, there wasn’t much solid data on the products in the marketplace, says Jean Halloran, Director of Food Policy Initiatives at Consumers Union, the public policy arm of Consumer Reports. The report aims to fill the data vacuum.

“We wanted to see, in terms of products which carried labels indicating they were not genetically engineered, that those labels were truthful and accurate,” said Halloran by phone from New York.

In North America, GMOS are found in an estimated 70-80 percent of processed food. The Non-GMO Project, backed by studies from scientists and genetic engineers, has questioned the safety of GMO foods citing studies that make connections to an “array of health risks and environmental concerns.”

Consumer Reports tested more than 80 different processed foods—including chips, infant formula, baking flours, and breakfast cereals—containing corn or soy. (As of 2011, approximately 88 percent of the corn crops and 94 percent of the soy crops in the United States came from genetically engineered seeds). After measuring two samples of each product for GMOs, researchers compared the results with labels on the product’s packaging. Foods with greater than 0.9 percent GMO ingredients were considered genetically modified.

The scientists found that foods labeled organic, or stamped with the Non-GMO Project’s Non-GMO Verified label, lived up to its name, and were in fact GMO-free. The former is to be expected by anyone familiar with the stringent organic labeling requirements mandated by the USDA’s National Organic Program.

Out of the 80 processed food products Consumer Reports’ scientists tested, those that claimed to be GMO-free—but lacked official certification—also lived up to the claim. In contrast, virtually all of the products labeled “natural,” and without Non-GMO verification, contained a “substantial amount” of genetically modified ingredients.

To complicate matters, the U.S. Food and Drug Administration (FDA) has never formally defined what the “natural” label really means. The ambiguity has paved the way for customer confusion, exacerbated by corporations like Kraft, which labels an entirely artificial food like Crystal Light “natural.” And several companies have faced lawsuits in recent years over the label.

Halloran says that people often think that “natural” means exactly the same thing as organic—or maybe even better. “In fact, often it doesn’t mean anything,” she adds. “And, there is no certification or testing program. Organic has to live up to 600 pages of regulations and have a certifier, but for natural, the company just puts the word on the package and makes it mean what they want it to.”

The best way to avoid buying GMO foods is by searching out either certified organic or Non-GMO Verified labels. Halloran says the consumer advocacy organization would like to see two things happen moving forward: the elimination of the “natural” label and mandatory labeling of genetically engineered products.

The November election cycle brings GMO labeling ballot initiatives in Oregon and Colorado, and Vermont recently passed legislation requiring GMO labeling (pending a high-dollar lawsuit), but that still leaves most U.S. consumers in the dark regarding the make-up of their food—especially when “natural” often means quite the opposite.