Living Green: The Missing Manual

Genetically Modified Foods

Opponents call them Frankenfoods. Proponents say they're hardier, more nutritious, and more resistant to pests and disease than regular crops. Many European consumers won't touch them, and many Americans don't realize they're already eating them. Although genetically modified (GM) foods have become increasingly widespread—particularly in the U.S.—they're still controversial.

A GM crop is engineered in a lab by adding a gene that's not normally a part of that plant. For example, the first GM crop to hit the market back in 1994 was a tomato, called the FlavrSavr, which had an added gene that made it more resistant to rot, giving it a longer shelf life.

Such crops are designed to improve upon nature, and they do offer lots of advantages. For example, some have been engineered to be resistant to pests, which means farmers can cut back on pesticides. Others resist diseases and herbicides (which farmers may use to kill weeds). Still others tolerate cold or drought better than regular crops, contain higher levels of vitamins and other nutrients, or deliver medicine.

So what about the Frankenfood claims? One of the biggest objections is that these crops have already made their way into the food chain and onto supermarket shelves without any long-term studies of their potential health effects. Introducing foreign genes into foods may have unexpected negative impacts on people who eat them. One study, for example, compared rats that ate GM potatoes with rats that ate ...