Allergies to soy, including soy flour, are relatively common. It's one of the eight most common food allergies, according to the Mayo Clinic website. For this reason, the Food and Drug Administration requires all manufacturers to label products containing soy. Infants and young children are more likely to develop a soy allergy, and many grow out of it by the age of 5. But you may develop a soy allergy at any time in your life.
Causes
If you're allergic soy flour or any other soy product, your immune system mistakenly identifies soy proteins as harmful. It produces immunoglobulin E, an antibody, and histamine, which causes the symptoms. Because you are allergic to soy, you may also be allergic to related foods, such as peanuts, beans, chickpeas, lentils and peas.
Symptoms
Symptoms usually occur shortly after consumption of soy and range from mild to life-threatening. You might experience itching, hives, eczema, a swelling of your lips and tongue, wheezing or shortness of breath. Some people have nausea, vomiting, abdominal pain or diarrhea. Soy allergies can cause anaphylaxis, a very serious, potentially fatal reaction. If you have difficulty breathing, a swollen throat, a sudden drop in blood pressure or a rapid weak pulse, seek emergency medical attention.
Tests and Diagnosis
If you think you or your child has a soy allergy, talk to your doctor and describe the symptoms. You'll probably be asked to take a skin or blood test. Your skin will be pricked to allow a tiny amount of allergen below the surface. If you're allergic, a rash will develop. In a blood test, a sample is analyzed for the presence of antibodies, your body's response to an allergen. These tests can also determine if you're allergic to other foods.
Treatment and Prevention
If you have only mild symptoms, your doctor might prescribe oral antihistamines. You can also buy these over the counter at the drugstores. If you're at risk of anaphylaxis, your doctor will probably prescribe an epinephrine auto-injector. Carry this with you at all times, and inject it into your thigh at the first sign of a serious reaction. Make sure your family and friends know how to use it. Consider wearing a medical-alert bracelet or carrying an alert card with you.
Prevention
The best way to prevent a reaction is to avoid any foods containing soy. Check labels carefully and ask detailed questions about ingredients and food preparation when you're eating out. Soy flour is commonly used in breads and other products. Avoid soybean curd, soy sauce, soy milk, tofu, edamame, miso, tempeh and tamari. Remember soy is widely used in many Asian dishes, as well as flavorings, vegetable broth, gum and starch. However, studies have shown that most people can safely eat soy lecithin and soybean oil. Many manufacturers add warnings if a product was made in a factory that handles soy, leading to a risk of cross-contamination, but this is not compulsory. If you're unsure about a particular food, it's best to avoid it.
