Soy allergy is an immune system response to soy protein that the body mistakenly believes is harmful. Once the immune system decides that soy protein is harmful, it creates specific antibodies to it. The next time the individual eats soy, the immune system releases massive amounts of chemicals, including histamine, in order to protect the body. These chemicals trigger a cascade of allergic symptoms that can affect the respiratory system, gastrointestinal tract, skin, or cardiovascular system. The symptoms of soy allergy will only occur upon re-exposure to soy. Not all soy products may cause soy allergy. Some fermented soy foods such as tempeh, shoyu and miso cause less allergy than whole soybeans, because the fermentation process partly breaks down the proteins. Only 0.5 of the population has soy allergy. Other foods that often cause allergy in adults are shellfish, peanuts (can cause severe anaphylaxis), nuts, fish and eggs.
In children, the pattern is somewhat different. The most common food allergens that cause problems in children are eggs, milk and peanuts.
Soybean oil allergy
The consumption of soybean oil, which only contains traces of soy proteins, does normally not produce allergic reactions. The European food legislation does not consider refined soybean oil as an allergen. The European Food Safety Authority (EFSA) evaluated 2 clinical studies and concluded that is very unlikely that the consumption of fully refined soybean oil will trigger a severe allergic reaction, even in susceptible individuals.
Symptoms of soy allergy
The reported symptoms of soy allergy include: acne, angioedema, rhinitis, anaphylaxis, asthma, atopic dermatitis, bronchospasm, colitis, conjunctivitis, diarrhea, diffuse small bowel disease, dyspnea, eczema, enterocolitis, fever, hypotension, itching, laryngeal edema, lethargy, pollinosis, urticaria, vomiting, and wheezing. If you suspect that you or your child may have soy allergy, you can conduct your own tests by completely eliminating soy for a several days. Then try just one soy product to see if it causes adverse reactions. Keep in mind that intolerance reactions can occur as long as 48 hours after ingestion of an offending substance. People with soy allergy may also cross react to certain foods, such as peanuts, green peas, chick peas, lima beans, string beans, wheat, rye and barley.
How to prevent soy allergy?
If possible, only breastfeed your child and do not give solid foods until it is 6 months or older. Avoid cow's milk, wheat, eggs, peanuts and fish during your child's first year of life.