Soy Allergies: An Overview

soy-products 1An allergy to soy is among the eight most common food allergies that affect children and adults in the U.S. Soybeans are a legume, closely related to beans, peanuts and peas, and are a popular additive in many different processed foods. Allergic reactions to soy vary widely, from very mild hives to the much more severe anaphylaxis. Fortunately, children with a soy allergy are not more likely to be allergic to any other legume.

About 0.4 percent of American children are allergic to soy. It is usually an early childhood condition, and the majority of soy allergy sufferers outgrow it by age three, and nearly all by age 10. Technically, it is one or more proteins in soy which cause an allergic reaction. The exact allergenic protein may vary between cases, but scientists have identified 15 different soy proteins that could cause a reaction.

Like other food allergies, a soy allergy involves a specific immune system response whenever the soy protein is present. Perceiving the soy protein as a threat, the body’s immune system overreacts, releasing immunoglobulin E (IgE) antibodies. These antibodies in turn cause symptoms like hives, watery eyes, digestive problems and, in rare instances, a fatal drop in blood pressure. Soy allergies are easily diagnosed through a skin prick or blood test which identify the IgE antibodies.

Foods to Avoid

Unfortunately, there is no cure or even a guaranteed prevention for soy and other food allergies. The only effective treatment available is strict avoidance of the allergen, and that includes all foods that contain or may contain soy protein. Edamame, soy milk and tofu are the more obvious foods to avoid, but soy protein is common in many processed products, and careful label reading is necessary to avoid accidental exposure. Common sources of hidden soy include granola and protein bars, cereals, baked goods and meat products. Other foods and food additives to avoid include:

  • – Miso
  • – Shoyu sauce
  • – Soy lecithin
  • – Textured soy or vegetable protein (TSP), (TVP)
  • – Teriyaki sauce
  • – Tamari sauce
  • – Tempeh
  • – Veggie burgers, Tofurkey® and other meat alternatives
  • – Soy-based infant formula

Highly refined vegetable oils derived from soy are usually safe, but should be avoided by children with an especially severe allergy. Ask your child’s doctor before cooking with these oils.

Because soy and soy products are so popular in Thai, Chinese and Japanese cuisine, people with soy allergies are advised to avoid eating at these and other Asian-inspired restaurants. Even if the establishment serves soy-free dishes, the chances of cross-contamination are too much of a risk.

Interestingly, most children with a soy allergy can tolerate larger amounts of their allergen than children with other food allergies. Typically, the dose of soy needed to cause a reaction is approximately 100 times that of other food allergies. Scientists are not sure why this is, but it is still no reason to allow exposure to soy. A tiny amount could potentially trigger a reaction, and even cases with mild symptoms could suddenly progress into full-blown anaphylaxis. As an extra precaution, doctors recommend that people with soy allergies always have access to Benadryl and an EpiPen or similar epinephrine injector. Should the worst happen, these medications could be life-saving.

Having a young child with a food allergy like soy can be very scary for parents. Soy is a hidden ingredient in many foods, making outings to restaurants, the grocery store and even a friends’ birthday party a stressful experience. If your child is diagnosed with a soy allergy, take heart knowing that he or she will very likely outgrow the condition. As long as your child has a soy allergy, however, taking extra precautions and planning ahead will go a long way in keeping your child safe and happy.

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