Soy Allergy – Symptoms, Tests & Treatment

Soy belongs to the family of legumes. It is one of the top ten food allergens. Soy allergy is one of the very common food allergies in both infants and adults. It is mostly outgrown by children till they reach adulthood; some of them retain the allergy in their adulthood as well. Soy lecithin allergy produces uncomfortable symptoms, but is usually not dangerous.

What is soy allergy?

Soy allergy is a hypersensitivity reaction occurring from the dietary substances produced from soy. Alike all other food allergies, soy allergy is also an overreaction of the immune system. It is not necessary that if you are allergic to soy, you would be allergic to other members of the legume family.


Soy allergy, as mentioned earlier is an immune system reaction. After ingesting soy products, the immune system identifies the proteins present in soy as harmful invaders and immediately triggers the production of immunoglobulin E (IgE) antibodies to the allergen i.e. soy protein. This procedure entirely takes place when the soy protein comes in contact with the immune system for the first time. During the next contact, the antibodies recognize the allergen in no time and signal the immune system to release some chemicals including histamine into the bloodstream of the individual. Histamine is largely symptoms in the body besides other chemicals that are released in the process.

Sources of soy protein

If you have allergy to a particular food, it is very important to know about the sources from which we derive them. Similarly, sources of soy protein include:

  1. Soybean (granules, chunks)
  2. Soy milk
  3. Soy sauce
  4. Tofu
  5. Textured vegetable protein
  6. Hydrolyzed vegetable protein
  7. Soybean butter
  8. Soy protein (isolate, concentrate)
  9. Soy (all forms)
  10. Edamame
  11. Miso
  12. Tempeh
  13. Meat alternatives
  14. Sometimes present in natural and artificial flavorings

Soy Allergy Symptoms

Signs and symptoms of soy allergy may range from mild to severe, mostly mild. In rare cases, fatal and life-threatening anaphylaxis symptoms are found. Mild symptoms include:

  1. Skin reactions such as hives and eczema
  2. Itching and swelling of tongue, lips and face
  3. Fever
  4. Fever blisters
  5. Runny nose and wheezing
  6. Abdominal pain
  7. Nausea, vomiting and diarrhea
  8. Conjunctivitis

Very rarely anaphylactic shock that includes severe difficulty to breathe, drastic drop in blood pressure, rapid pulse, dizziness or lightheadedness and sometimes loss of consciousness

Additional symptoms are found in infants including crankiness, irritability and soy avoidance.

The onset of these symptoms usually takes place within few minutes to hours of consuming dietary sources of soy protein.

Test & Diagnosis

Signs and symptoms are the foundation stones on the basis of which one should seek help of the diagnosis centers for confirming themselves if they have at all been victimized by soy allergy. Proper diagnosis leads to proper treatment. Hence, the diagnosis is mandatory. Some of the diagnosis methods include:

Skin prick test

In this test, a drop of allergen (soy protein) is administered on the skin and the top layer of skin is pricked with the help of needle right through the extract. If a person is allergic to soy, a red bump will appear at the spot where the skin was pricked. It looks similar to mosquito bite.

Intra-dermal skin test

This test is a more sensitive form of skin prick test and is usually carried out to confirm the presence of soy allergy in an individual if all other tests are found negative. The suspected allergen is incorporated into the skin with the help of a syringe.

Blood test (RAST test)

This is a test mostly done on babies (less than 1 year old) to determine the level of IgE antibodies in the body because their skins do not react well to skin prick test.

Elimination diet

In this diagnosis method, a person completely stops consuming the dietary sources of allergen for a couple of weeks and then gradually incorporates them back in diet one by one while keeping a track of the symptoms.

Food challenge test

It has been considered as the best diagnosis method so far. In this test, a person is administered with increasing amount of allergen and the symptoms are checked for.

Risk factors

Although soy allergy can crop up almost suddenly in an individual yet certain factors are responsible to heighten the risk of developing the allergy. Such factors include:

  1. Age: Soy allergy is commonly found in children, mainly in infants and toddlers.
  2. Family history: If problems such as hay fever, asthma, eczema and hives are commonly found in a family, other members are definitely at high risk of developing soy allergy.
  3. Other allergies: It has been seen in some cases that people who are allergic to milk, wheat, beans (legumes) or any other food are also allergic to soy. Thus, other food allergies put you at considerable risk of developing allergic reaction to soy.


Infants affected with soy allergen respond quite quickly as well as effectively on being fed with hydrolyzed protein formula instead of soymilk formula. Elimination of soy protein sources is the best treatment for people having soy allergy.

Intensive research in this genre has successfully brought in several treatment approaches such as oral, sublingual and epicutaneous immunotherapy or desensitization.

Diet, nutrition and caution

One should be extremely careful while purchasing and consuming any food item. Labels should be read without any failure else, the food product you are purchasing might prove to be an unknown source of danger. In case of any doubt with the food label, you may directly contact the manufacturer for the correct insight into the ingredients.

You should be diligent and cautious to ask questions while you are eating at a restaurant.

Highly refined soybean oil is considered devoid of risk and hence can be consumed by people with soy allergy. Still it is advisable to consult your doctor whether you should have soybean oil or not. Asian cuisines should be avoided at large due to the presence of soy as a common ingredient or possibility of cross contact in soy-free preparation.

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Dr. Jagdev Singh

Dr. Jagdev Singh is a qualified Ayurvedic Practitioner and Herbalist with B.A.M.S. and M. Sc. in Medicinal Plants. He has a wealth of experience in using Ayurveda to treat patients, including the use of herbal medicine and personalized Ayurvedic diets. His passion for spreading accurate and scientific information about Ayurveda and Medicinal Plants led him to create Ayur Times, a trusted resource for those seeking reliable information on the topic. Through his dedicated work, Dr. Singh has helped thousands of patients find relief and improve their health with Ayurveda and Herbal Medicine.

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