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Genetically modified foods, which are also called genetically engineered foods, biotech foods and bioengineered foods, are produced by recombining DNA of two different organisms (gene splicing). This is a process to remove a gene or genes from one organism and place them into the DNA of another to introduce new traits to the second organism. This can help make crops more resistant to certain pests and herbicides.

DNA contains the genetic blueprint for all life forms. Specific parts of DNA contain the codes, or genes, necessary to produce proteins. These proteins contribute to the creation of a specific trait by stimulating biochemical reactions or by acting as structural or storage units of a cell.

Traditional genetic modification techniques include plant grafting (attaching a portion of one plant to another) and hybridization (sometimes called cross-breeding), in which two different plants are bred to produce offspring with qualities of both parent plants.

These traditional methods have been used for hundreds of years to introduce a desired trait from one plant into another. However, traditional techniques have limitations. They introduce thousands of genes, instead of just one or a few particular genes. This can have unpredictable results. The new plant is likely to have as many undesirable new traits as desirable ones. The process of producing a plant with the desired trait(s) and few or no undesired traits involves a great deal of trial and error and can take a long time. Generally, only plants that are closely related can be used.

On the other hand, gene splicing allows scientists to introduce just the desired gene or genes into the target plant. Thus, the likelihood of introducing undesirable new traits may be reduced. In addition, gene splicing does not require that only closely related plants be used. Genes from nearly any type of organism may be used, including genes from bacteria and insects, and vertebrates such as fish or mammals.

Reasons foods may be genetically modified include:

• To grow year-round
  
• To be more resistant to pests and adverse weather conditions such as drought
  
• To tolerate herbicides for more effective weed control
  
• To increase appearance, nutritional content and storage capacity
  
• To resist plant diseases

Genetically modified foods are relatively new, first becoming available in the 1990s. The first genetically modified whole food was a tomato introduced in 1994. It was designed to ripen more slowly, remain on the vine for longer periods of time and stay fresh longer after ripening than other tomatoes. The U.S. Food and Drug Administration (FDA) determined that this genetically modified tomato was as safe for consumption as traditionally grown tomatoes. Since then, the FDA has approved over 50 additional genetically modified foods.

According to the U.S. Department of Agriculture (USDA), genetically modified crops made up 40 percent of corn and 81 percent of soybeans grown in the United States in 2003. Genetically modified plants are usually used to make the ingredients (e.g., oils, flour, cornmeal) for a variety of processed foods such as breads, cereals, corn chips, hot dogs and soda. These plants may also be used as animal feed or for non-food purposes (e.g., fabric).

Proponents are constantly looking for new ways to use genetic foods. For example, plans were recently announced to plant the first commercial crop of genetically modified potatoes. These potatoes have been modified so they can be used in the production of papers and adhesives and are not intended to be used as food.