For more than a decade, author Jeffrey Smith has been raising concerns over the widespread production and distribution of genetically modified foods in the United States. Dr. Oz talks with Jeffrey about the problems foods produced from genetically modified organisms (GMOs) pose and how you can keep them out of your diet.

Since the 1970s, scientists have been researching ways to make crops easier to produce by genetically altering seeds to better fight off insects and tolerate herbicides that kill unwanted weeds. In the 1990s, Jeff says big agricultural biotechnology companies were allowed to saturate the U.S. corn, soybean, cotton and canola markets with genetically modified crops—without taking the time to research long-term side effects GMOs may have on humans, animals and the environment.

While Canada, Argentina, Brazil and China have followed the United States and jumped on the GMO bandwagon, Jeffrey says such food products are banned in Europe and Japan. "It's not the political establishment of Europe that has kept it out—it's the consumer concern that has kept it out," he says. "A genetically engineered food is a food in which the gene from one species has been forced into the DNA of another species and the process itself creates all sorts of unpredicted side effects."

Allergies, toxins, new diseases and nutritional problems could all be side effects of GMOs and Jeffrey says if you want to steer clear of genetically modified food, there are a few things you can do:

• Buy organic foods. "[Organic farmers] are not allowed to use GMOs," Jeffrey says.
• Stay away from non-organic soy, corn, cotton, canola and prepackaged foods. "The cotton and canola are used for vegetable oil but soy and corn derivatives are in nine out of 10 boxed and packaged foods," he says.
• Look for products labeled "non-GMO." While there is no U.S. law mandating food companies label genetically modified foods, Jeffrey says some companies voluntarily label non-GMO products.