Think You Might Have a Soy Allergy?

Concerned that you might have a soy allergy? You just might have one. Soy is one of the eight most common allergens. Living with a food allergy creates challenges and requires careful meal planning, reading of menus and scanning ingredient labels. Allergic reactions vary widely from individual to individual, ranging from mild to severe.

The Food Allergy Research and Resource Program at the University of Nebraska-Lincoln has been researching the issue for more than 20 years. Dr. Melanie Downs is an assistant professor with the program. Her research focuses on the identification, characterization, and detection of food allergens. She also works with the food industry on food allergen management. We asked her some of the questions we’ve received at Best Food Facts.

What is the cause of most food allergies?

Dr. Downs: “A food allergy occurs in certain individuals whose immune systems have generated a particular type of antibody — IgE – which specifically recognizes proteins from a particular food. After these IgE antibodies have developed and the person consumes the food in question, interaction of the food proteins with the IgE antibodies will result in the release of substances in the body (e.g histamine), which will cause symptoms of an allergic reaction.”

“While it has been known for many years that food-specific IgE is required to develop a food allergy, it’s still unknown exactly why certain individuals develop IgE against foods and other individuals don’t. Having food-specific IgE antibodies is necessary for an allergic reaction but some individuals who have such antibodies do not experience allergic reactions on ingestion of the food.”

If someone is allergic to soy, what is the part of the food that causes a reaction?

Dr. Downs: “The food components responsible for soy allergies, like nearly all food allergies, are the naturally occurring proteins in the food. Foods can have a number of different allergenic proteins, and allergic individuals may react to one or more of these allergens.”

If you are allergic to soy, should you avoid foods cooked in soy oil? Find out here.

What are the typical reactions that indicate a food allergy?

Dr. Downs: “The symptoms of an allergic reaction to foods can involve various different organ systems, including the following:

skin – hives, swelling, eczema
respiratory tract – runny nose, throat swelling, asthma
gastrointestinal tract – nausea, vomiting, abdominal pain
cardiac system – low blood pressure, arrhythmia

“Severe allergic reactions can also result in anaphylaxis, shock, and death. The type of symptoms experienced during a food-allergic reaction can vary widely between allergic individuals and between reactions for a single individual.”

What’s the difference between a food allergy and a food intolerance?

Dr. Downs: “The primary difference between food allergies and food intolerances is that the biological mechanisms for food allergies involve the immune system, while the mechanisms for intolerances do not. In most cases, food allergies are also generally considered to present more severe and immediate health risks than intolerances; sulfite-induced asthma is an exception as it is not an allergic reaction but can cause immediate and severe reactions.”

Do soy allergies usually begin in childhood or later in life?

Dr. Downs: “Soy allergies have historically developed most commonly in infancy or early childhood, which is similar to milk, egg, and wheat allergies. The development of soy allergy in infancy may be related to the use of soy formula as a substitute for milk formula. As that practice is decreasing, the prevalence of soy allergy in infancy may decrease as well. It is possible to develop a food allergy later in life as well.”

Are soy allergies becoming more common?

Dr. Downs: “While there is some evidence that food allergies in general are becoming more common, it is difficult to get good estimates of the prevalence of allergies to some individual foods, including soy. If the rates of soy allergy are increasing at all, they do not appear to be increasing any faster than other food allergies.”

What are some common misconceptions about food allergies?

Dr. Downs: “Some consumers with histories of serious allergic reactions do not seek advice from an allergist and do not carry the life-saving drug, epinephrine. They should do both.”

Food allergies are caused when a person’s immune system creates a particular type of antibody. Soy allergies are caused by the protein. Reactions can vary; if you have a serious reaction, consult with a physician.