Genetically modified organisms—GMOs—refers to foods that have been genetically altered to suit a particular purpose. In the case of crops, the purpose of genetic engineering is to create plants that can better resist insects, tolerate viruses, and withstand otherwise lethal doses of pesticides. At first glance, it may seem like creating “superior” organisms sounds like a great idea, but this not the case. As with any new, radical technology, the uncertainties and potential health dangers surrounding GMOs are enormous.

One of the main reasons GMO foods are problematic is that genetically modified food often contains proteins that may be allergenic. Take one common example—soybeans that have protein from nuts inserted into their DNA. This combination could be dangerous—even fatal—if you are allergic to nuts. Another example is the transfer of milk protein into vegetables, which could pose a health threat for the thousands of people with milk allergies.

Fortunately, the FDA requires special labels for genetically modified foods that contain proteins that could cause allergic reactions. However, if the food doesn't contain potential allergens, the simple fact that it was produced by a different—possibly harmful—process is not enough to require a label.

Another health-related danger of GMO is that some genes added to genetically modified plants could actually cause the plants to absorb dangerous metals, such as mercury, from the soil. The removal of these metals from the soil creates safer, less toxic sludge, which farmers can then use as a powerful fertilizer. The metals that the plants soak up are stored in their inedible parts, and the edible parts are supposedly safe to eat.

The tough thing about GMOs is that they are very difficult to avoid. In fact, if you’ve ever eaten out, there’s a chance that you and your family may have already been exposed to GMOs. In one estimate from the Grocery Manufacturers of America, 70–75 percent of what you find on U.S. grocery store shelves contains at least some genetically modified ingredients, including tomatoes, soybeans, corn, canola, rice, potatoes, and squash.

Fortunately, choosing organic or biodynamic foods can all but guarantee that you are GMO-free.