Soy Allergy

Henry Ford had such a keen interest in soy that he once wore a suit made entirely from soybeans. While this fashion statement never caught on, soybean production exploded. An inexpensive source of protein, soy can be found in many processed foods, making this major food allergen difficult to avoid for people with soy allergy.

It is estimated that approximately 0.4 percent of American children, or about 298,410 under the age of 18, are allergic to soy, which is a member of the legume family. Soy allergy symptoms are usually mild; soy-related anaphylaxis—a serious and rapid-onset reaction that may cause death—is rare.

Soy foods to avoid

Soy is found in some infant formulas, canned broths, soups, canned tuna, processed meats and hotdogs, and many other processed foods. Those with soy allergy should be aware that soy is often found in Asian cuisine and sometimes contained in deli meats, chicken nuggets, low-fat peanut butter, alternative nut butters and even vodka.

Most individuals allergic to soy can safely eat highly refined soybean oil (not cold pressed, expeller pressed or extruded oil). Ask your allergist whether or not to avoid this ingredient. Caution should also be used when eating foods that have been fried in any type of oil, due to the risk of cross-contamination. For example, if a soy-containing food is fried in oil, that oil will contain soy protein. If a non-soy-containing food is then fried in that same oil, the food could cause a reaction in an individual allergic to soy.

Another question that often arises for those allergic to soy is whether they can eat foods that contain soy lecithin—a mixture of fatty substances derived from soybean processing. Soy lecithin can be safely consumed by most soy-allergic people, but ask your allergist if soy lecithin should be avoided.

Frequently asked soy allergy questions

Will my child outgrow soy allergy?

An allergy to soy may be more persistent than previously thought.  Researchers recently found that nearly 70 percent of patients enrolled in their study had outgrown their soy allergy by the age of 10. Ongoing studies are looking into the relationship between a child’s soy IgE level and the rate of achieving tolerance. Early research indicates that the more that a child’s IgE level has increased, the more likely he or she is to have a persistent soy allergy.

Is soy allergy related to nut or peanut allergy?

While soybeans and peanuts are both legumes, the chances of cross-reactivity among legumes are minor. Soybeans are unrelated to tree nuts (e.g., almonds, walnuts, cashews). A soy-allergic individual is no more likely to be allergic to tree nuts than he or she would be to another food.

Reprinted and revised with permission from the American College of Allergy, Asthma & Immunology