What Are GMO Foods, and Are They Dangerous?

The loudest public food fight right now is about GMOs, or genetically modified organisms. Scientists add genes to corn, soybeans, and other plants, usually to protect the crops from insects or herbicides.

Proponents say the genetic tinkering makes crops easier to grow and cheaper. But many consumers and food-safety watchdogs worry that GMOs pose an unnatural threat to our health and the environment. Opponents say that GMOs have been linked to depression, allergies, infertility, and even cancer.

Although GMOs have been in our food supply for 20 years, the controversy has moved to center stage. Recent documentaries and experts on The Doctor Oz Show have fanned the flames. About 75 percent of consumers say they are concerned about the safety of genetically modified foods, according to a New York Times survey. Maine and Connecticut recently passed bills requiring labeling of all foods made with GMOs; many other states are considering mandatory labeling. The European Union already requires labeling, and several countries, including France, have banned the planting of genetically modified crops. So are GMOs safe—or should you avoid them at all costs? Here, a look at the evidence.

What You’ve Heard
Roughly 90 percent of the corn, canola, soybeans, and sugar beets grown in this country have bits of DNA that originally came from a lab. The soy in some multigrain breads, the canola in margarine, and the corn syrup in everything from ketchup to soda are likely genetically modified. Unless you’ve been eating only foods labeled 100 percent organic—which must be GMO-free—you probably have GMOs in your system now.

In a big red-flag–raising study, French researchers reported last year in Food and Chemical Toxicology that rats developed huge tumors after living on genetically modified corn for two years. “Genetic engineering can have unintended consequences,” says Bill Freese, science policy analyst for the Center for Food Safety. Artificial genes force plants to produce unnatural proteins, he says, and no one knows how those may affect human health.

… But Not So Fast
Scientists immediately criticized the French study (and it was ultimately retracted by the journal in November 2013.) For one thing, the types of rats used in the study were highly prone to cancer, so it was predictable that some would develop tumors after eating GMOs, notes Nina Fedoroff, a professor of biology and life sciences at Penn State University. She adds, “We’ve eaten these foods for 20 years and aren’t walking around with giant tumors.”

Hundreds of other studies have found no trouble with GMOs, says Ruth MacDonald, professor and chair of food science at Iowa State University. After looking at more than 130 research projects—including animal studies and searches for known toxins or allergens in GMO foods—the European Union concluded that there’s nothing especially risky about them.

In September, the editors of Scientific American denounced the efforts to label GMO foods, stating that there’s no proof that so-called Frankenfoods can endanger people’s health. Adding genes to crops isn’t any more dangerous than traditional breeding, which farmers have done for thousands of years, the American Association for the Advancement of Science declared in 2012. Old methods of modifying crops mixed tens of thousands of genes with unpredictable results. The fact that scientists can now insert single genes into corn or soybeans shouldn’t raise any new alarms, says Fedoroff.

The Bottom Line
There doesn’t appear to be a scientific reason to ban GMO foods from your pantry to protect your health. But it is healthy to limit your intake of the processed foods that often contain them. And don’t assume that GMO-free packaged food is necessarily healthy. Organic cookies can still contain too much sugar or salt.