Therefore, when a genetic engineer adds, say, a bacterial gene to a tomato, he or she is essentially adding a bacterial protein to that tomato. In most cases these added proteins will likely prove safe for human consumption. Nevertheless, just as with conventional food additives, substances added to foods via genetic engineering may in some instances prove hazardous. A major concern about adding proteins to foods via genetic engineering is that they may cause susceptible individuals to become allergic to foods they previously could safely consume. Food allergies are a serious public health concern, which food allergists estimate affect roughly 2.5 - 5 million Americans.
Allergic reactions cause discomforts and in some cases life-threatening anaphylactic shock.
Since virtually all known food allergens are proteins, foods with new proteins added via genetic engineering could sometimes become newly allergenic. These concerns about food allergy are real. One company has already dropped plans to commercialize soybeans with a brazil nut gene after testing revealed the soybeans were likely to cause allergic reactions in brazil nut allergic individuals. Unfortunately, food allergies are poorly understood, and in many cases scientists will not be able to test the potential allergenicity of genetically engineered foods. FDA, at least in principle, is applying the same regulations to substances added to foods via genetic engineering as apply to conventional chemicals added to food.