Soy protein, derived from soybeans, is a common food allergy in children that is usually outgrown by the age of three. Recently, however, children are not outgrowing the allergy so it is now seen more frequently in adults. The initial reaction typically occurs in infants after switching to a soy-based formula due to an allergic reaction to a milk-based formula. Some people who are allergic to soy may also be allergic to legumes such as peas, peanuts, lentils and garbanzo beans (chick peas).
Soy allergies are generally accompanied by mild symptoms, although some can be more severe and result in anaphylaxis. Most people just experience general discomfort. Symptoms occur within minutes to a few hours of consuming the food. They include:
- Hives and/or itching
- Tingling or swelling of the lips, tongue, throat
- Wheezing and difficulty breathing
- Nausea, vomiting, diarrhea
- Fainting or dizziness
On rare occasions, allergic reactions may result in anaphylaxis, which requires immediate attention and symptoms include:
- Constriction of airways
- Shock and a severe drop in blood pressure
- Rapid pulse
- Dizziness or loss of consciousness
If you experience any of these symptoms, even if mild, following consumption of soy or soy-containing products, contact your doctor about allergy testing. Your doctor may recommend one of two tests:
- Skin test – A skin prick is used to expose small amounts of the protein to your body. A food allergy is confirmed by the presence of a raised bump or hive at the prick location.
- Blood test – A blood test, also referred to as an IgE test, measures your immune system’s response to the proteins found in soy by counting the number of specific antibodies in your blood.
The only way to prevent a reaction is by avoiding soy and soy-containing products. Read labels carefully and look for these words:
- Glycine max
Some processed soy products, like soy sauce, may or may not cause a reaction. For example, fermented soy products such as tempeh and miso cause a lesser allergic reaction than raw soy since the fermentation process partially breaks down the proteins. It is important to note that peanuts and soy contain similar allergy-causing components, so you may want to consider being tested for both allergies. Since soy protein is a common allergy in infants, breast milk is a safe alternative to soy-based formulas. Be sure that any solid foods introduced are also soy-free. Food Handling: Depending on the severity of the soy allergy, some people may have an allergic reaction simply from being in contact with soy. Avoid touching soy or products that contain soy. Take precautions to avoid cross-contamination by using separate cooking utensils (cutting boards, serving spoons, pots and pans, etc.) for soy-containing products and by washing their hands in between handling of these foods. Shopping: Soy products are increasingly more common on supermarket shelves due to the perceived health benefits. The FDA mandates the labeling of foods that contain the eight major food allergens, which includes soy. Take a closer look at soy-based foods:
- Soy sauce
- Soy flour
- Soy nuts
- Soy milk
- Soy sprouts
Soy in Disguise: Read labels carefully and look for these words:
- Hydrolyzed vegetable protein (HVP)
- Textured vegetable protein (TVP)
- Monosodium glutamate (MSG) – common in Chinese food
- Vegetable oil
- Vitamin E
- Natural flavoring
- Vegetable broth
- Vegetable gum
- Vegetable starch
Eating Out: When dining out, ask detailed questions about ingredients and how the food was prepared – your health and safety are at stake! There’s a high risk for cross-contamination in the kitchen so be sure to clearly express your food allergy to the server or cook. Ask to look at the food package if necessary. Be especially careful is restaurants that serve Asian cuisine, since soy ingredients are common.
Don’t Go it Alone
A new diagnosis can be scary. Be sure to build a support of family, friends and healthcare professionals to help you manage your soy protein allergy. Soy foods are rich sources of protein, fiber, calcium, B-vitamins and iron. Soy products have recently become more popular, yet there are many people who never consume soy products. For this reason, avoidance of soy products has less of an impact on your nutritional status than other food allergies. Consider talking to a doctor or dietitian when eliminating any foods from your diet. They may recommend an adjustment in your meal plan or a supplement to replace nutrients lost by eliminating the offending food and food ingredients. Also talk to your doctor about how to prepare for a reaction. You may treat a mild reaction with oral antihistamines to reduce signs and symptoms and relieve discomfort. If you are at risk for severe reactions or anaphylaxis, your doctor may advise you to wear a medical alert bracelet and/or prescribe an injectable epinephren (EpiPen) to carry with you at all times.
American College of Allergy, Asthma and Immunology http://www.acaai.org
American Academy of Allergy, Asthma and Immunology http://www.aaaai.org
Asthma and Allergy Foundation of America http://www.aafa.org
The Food Allergy & Anaphylaxis Network http://www.foodallergy.org
The Food Allergy Initiative http://www.faiusa.org