If you have an allergy to soy, it means your body has misidentified any or all of the 15 or so proteins in soy as dangerous substances. When you eat anything that contains soy, your body reacts by releasing an antibody called immunoglobulin E. The antibody then sends out a team of chemicals to combat the soy allergens, even though soy is perfectly safe for human consumption. The way your body reacts to the chemicals it releases is what dictates the types of allergic symptoms you suffer, which can range from a runny nose to anaphylactic shock.
In order to prevent any allergic symptoms, your best bet is to avoid soy and all products containing soy. One way to know what's in packaged food is to read the label. The ingredient list might mention soy, soya, soybeans or glycine max; in addition, the Food and Drug Administration requires food producers to print a warning on the label of any food that contains soy. However, the label won't necessarily say whether the food was made in a facility that also processes soy even when it might.
Soy is a main component in many popular foods, including edamame, soy milk, soy sauce, soy sprouts, tofu and tempeh. It's also a very common ingredient in vegetable broth, vegetable gum and vegetable starch. Many Asian foods contain soy, as do a number of kinds of artificial flavorings. Sometimes soy is hidden in hydrolyzed vegetable protein, textured vegetable protein, lecithin, monosodium glutamate, vegetable oil and vitamin E. It can also be found in meat substitutes, butter substitutes, ice cream, candy and condiments. When it comes to babies, many infant formulas contain soy, too. Once a child is diagnosed, it's important to keep an eye on what he eats and to teach him about his allergy as soon as he's old enough.