Soy Allergy Guide | Lifelab Testing

Soy Allergy Guide

Last Updated: 20th February 2023 · Written by Kate Young

Soy is a common ingredient in many processed foods, as well as commonly found in baby formula. For many people, ingesting soy is harmless and a good protein source, especially for plant-based diets. Soy allergy occurs when your body reacts to soy protein. If you ingest or drink soy and you’re allergic to it, your immune system views the soy protein as “harmful,” which leads to the production of antibodies like histamine, to generate soy allergy symptoms. Soy allergy can sometimes be very severe, leading to a life-threatening condition called anaphylaxis. Soy allergy is observed in children as young as under three years old, though they may outgrow the allergy later on {1}. Even though kids have a higher risk of developing soy allergy, it is common for adults to develop it, especially if they already have preexisting food allergies.

Soybeans are a part of the legume family which also includes foods like lentils, peas, kidney beans, and peanuts. Immature soybeans are also known as edamame.  Although most people know soy as soy milk or in tofu, it is also present in some processed foods that you may not suspect. Of all the food allergies, soy is one of the most challenging items to avoid as it is  present in many processed foods, condiments, and other products. Soy is among the top food allergens affecting people all around the world.

Soy allergy symptoms

Soy allergy symptoms appear within minutes to a few hours after contact or consumption. These symptoms vary from one person to the next, ranging from mild to severe. Common soy allergy symptoms include:

Woman with itchy and red neck
A woman with an itchy neck
  • Abdominal pain.
  • Red skin.
  • Diarrhoea.
  • Runny nose, wheezing, or trouble breathing.
  • Itchy mouth.
  • Hives and soy allergy rash.
  • Itching and swelling.
  • Nausea.
  • Vomiting.
  • Anaphylaxis (difficulty breathing, increased heart rate, drop in blood pressure, dizziness, and confusion).
  • Swelling of lips, mouth, or other body parts.

When one experiences severe symptoms like wheezing, trouble breathing, or anaphylaxis, you should contact emergency care or rush to the emergency room. Anaphylaxis is a severe condition that could result in shock, coma, or even death. It is, however, a rare case. If you have severe soy allergy symptoms, you should always have an EpiPen to carry at all times, which you’ll administer in case you accidentally consume soy.

You’ll know that you are not experiencing a soy intolerance if you experience less severe, mostly digestive symptoms. If you’re unsure whether you have a soy allergy or soy intolerance, you can take a Complete Body Test which analyses your blood sample for both soy allergy and intolerance.

Foods containing soy

Soy products come in various forms, and you need to know these multiple forms to identify soy ingredients and products to avoid.

Soy lecithin

Soy lecithin is a non-toxic food additive. It is used as an ingredient in foods that require a natural emulsifier. For example, soy lecithin helps control sugar crystallisation when used in chocolates. In some other products, it helps improve their shelf life. Soy lecithin can also be used to prevent or reduce splattering when frying some foods. Even though soy lecithin comes from soy, many people with soy allergy can tolerate it because it doesn’t contain any of the proteins that those with soy allergy react to. Soy lecithin allergy is separate from a soy allergy.

Soy sauce

Soy sauce contains both soy and wheat, making it hard to decipher whether you’re suffering from a wheat allergy or soy allergy. In such cases, getting an Allergy Test is the best choice to get to the bottom of the issue. If you find out that you have a wheat allergy, you can use tamari sauce instead of soy sauce, since tamari sauce is similar to soy sauce but without wheat.

Soy milk

Approximately 15% of infants with cow milk allergy also suffer from soy milk allergy {2}. When your baby has these allergies, it is best to settle for hydrolyzed formulas that ensure that the proteins have been broken down and are less likely to cause an allergic reaction. In all elemental formulas, the proteins have been broken down to an extent with a very low probability of causing an allergic reaction.

Soybean oil

This oil doesn’t contain any soy proteins. It’s safe for those with soy allergies to consume it. However, you need to speak with your doctor beforehand, especially if you suffer from severe reactions to soy.

How to test for soy allergy at home

Our Basic Allergy Test

Testing for soy allergy is quite simple, and it’s not something you need to go to the doctor’s office to get. If your doctor agrees that you don’t have any underlying conditions that could be causing soy allergy symptoms, then you should take a home-lab Allergy Test. This test doesn’t require you to leave the comfort of your home or visit the doctor’s office. All you’ll need to do is place your order for the allergy test, which you’ll receive around three days after the order, then carefully take your sample and send it back to the labs. Your sample will thoroughly be examined by scientists in the lab for any allergies that could affect you, either from your food, environment, or drinks. You’ll then get an email with your results telling you which foods you need to avoid because of specific allergies you have.

Soy allergy treatment

The most effective treatment for soy allergy is the avoidance of soy. Whether it’s in processed food or the grain itself, it doesn’t matter. You’ll need to be careful to stay symptom-free. If you have a soy allergy, you need to get familiar with ingredients in every processed food so you’d know what to avoid. Always ask the manufacturer questions if you’re unsure if it contains soy proteins, and they’ll be more than willing to answer you. When eating out, inform the host or chefs of your allergy to avoid accidental consumption of this legume.

When being careful not to experience soy allergy symptoms, you must look for soy products or ingredients in non-food items (like candles, synthetic fabric, makeup, and others) and shared equipment. You will often find items made on the same surface as soy, increasing the chances of cross-contamination. So many foods and drinks also contain soy, and your ingredient-reading ability will save you from soy allergy symptoms.

Soy allergy foods to avoid

Since many foods and drinks contain soy, here are some that you must avoid:

  • Soy in all forms, including soy flour, soy fibre, soy albumin, and soy grits.
  • Soybean (curd and granules).
  • Soy protein (concentrate, isolate, and hydrolyzed).
  • Soy non-dairy alternatives, including soy milk, soy ice cream, soy cheese, and soy yoghurt.
  • Soy nuts and soy sprouts.
  • Soy sauce.
  • Tofu and textured vegetable protein (TVP).
  • Natto.
  • Tempeh.
  • Tamari.
  • Edamame.
  • Miso.
  • Hoisin.

Some foods that could contain soy include:

  • Low-fat peanut butter.
  • Meat substitutes.
  • Baked goods (bread, cookies, and crackers).
  • Cereals.
  • Frozen dinners.
  • High-protein energy bars and snacks.
  • Ice cream.
  • Infant formula, baby foods, and cereals.
  • Processed meats, like deli meats.
  • Canned broth and soup.
  • Canned tuna and meat.
  • Salad dressings, mayonnaise, gravy, and sauces.
  • Vegetable oil.

Not all soy ingredients use the name “soy,” so you can find soy products labelled as:

  • Glycine max.
  • Monosodium glutamate (MSG)Hydrolyzed vegetable protein (HVP).
  • Mono-diglyceride.

Final thoughts on soy allergy

Living with a food allergy can be difficult, especially when it’s a common ingredient in a lot of packaged foods and products. You can use the above list to give an idea of where you’ll start looking once you’ve taken your allergy test and confirmed that you’re indeed allergic to soy. Whenever you doubt an ingredient, you can either not buy it or call the manufacturers, and they’ll be more than willing to help you. Once you know which foods to avoid, you can take control of your diet and never suffer from soy allergy symptoms again.


  1. American College of Allergy, Asthma & Immunology. Soy. (
  2. Candreva, A. M., Smaldini, P. L., Curciarello, R., Cauerhff, A., Fossati, C. A., Docena, G. H., & Petruccelli, S. (2015). Cross-reactivity between the soybean protein p34 and bovine caseins. Allergy, asthma & immunology research, 7(1), 60–68.

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