What Is a Soybean Allergy?

Soybean allergy is one of the most common food allergies in babies and children. However, most kids will outgrow a soybean allergy by age 10. A member of the legume family, soy is also one of the eight most allergenic foods known to cause an allergy attack.

A soy allergy is a type of immune response triggered by ingesting soy or soy products. The immune system normally reacts to allergens by protecting us from any kind of a negative response. However, the immune response of an individual with a food allergy is oversensitive. When faced with an allergen, the system reacts by releasing substances that cause allergy symptoms.

Even the smallest amount of soybeans can cause an allergic reaction, so it’s important to know how to avoid exposure to products containing soy and be able to spot the symptoms of an allergic reaction if one is ingested. The good news is that most people have moderate reactions and anaphylaxis is rare with a soy allergy.

Soybean Allergy Symptoms

The most common cause of an allergic reaction to soy is direct contact by eating soy or soy products. People with a soybean allergy may experience an allergic reaction anywhere from a few minutes to a few hours after consuming the allergen.

Most Common Symptoms of Soybean Allergies

  • Swelling of the lips, face, tongue, and throat
  • Difficult breathing or wheezing
  • Stuffy or runny nose
  • Itching in the mouth
  • Abdominal pain, diarrhea, nausea or vomiting
  • Skin conditions such as hives or eczema

In severe cases, an allergy to soy can result in anaphylaxis, a sudden, severe, and life-threatening allergic reaction that can involve several areas of the body. Even though this reaction is very rare with soybean allergy, health care professionals still recommend to keep an epinephrine auto-injector with you at all times. An epinephrine injection is the only treatment for anaphylaxis.

There are several steps involved in testing for and diagnosing a soy allergy. Consult your allergist or physician for further information.

Avoiding Exposure to Soybean Products

Even trace amounts of a food allergen can cause a reaction. So, in order to prevent an allergic reaction to soy, you must avoid soy or soy products in all forms. Since soy is found in many foods it’s important that you carefully read all food labels. Look for the words “soy,” “soya,” and “soybeans.” Some of the more common products to avoid include:

  • Tofu
  • Miso
  • Soy milk
  • Soy cheese
  • Soy ice cream and soy yogurt
  • Soy flour
  • Soy sauce
  • Shoyu
  • Edamame
  • Natto
  • Tamari
  • Tempeh
  • Yuba
  • Okara
  • Niname
  • Kinkako
  • Vegetable oil
  • Vegetable gum

Additionally, soy may be found in products such as:

  • Infant formulas
  • Canned broths and soups
  • Canned tuna
  • Processed meats and hot dogs
  • Energy bars, baked goods, cereals, crackers
  • Asian cuisine

Also be on the lookout for words on labels such as glycine max, hydrolyzed vegetable protein (HVP), textured vegetable protein (TVP), monodiglyceride, and monosodium glutamate (MSG), which all contain soy.

Special Considerations for Soybean Allergies

Babies and infants who begin a soy-based formula may show signs of a soy allergy. If this happens, speak with your doctor about alternatives to soy formula. Symptoms typically decrease if an infant is breastfed or fed with a milk-based formula.

Since soy and peanuts are both legumes, some people wonder if they should avoid peanuts. Having a soy allergy does not mean you will have an allergy to peanuts. They are considered two different allergens and many people with a soy allergy can eat peanuts without having an allergic reaction. Consult your doctor if you have questions about the safety of consuming peanut-based products.

The other issue facing people with a soybean allergy is cross-contact. Cross-contact can happen when a food is exposed to soy during processing or handling. For example, a glass that was previously used to drink soy milk from is now being used to serve milk-based milk to a person with a soy allergy.

Regulations Related to Soybean Allergies

The U.S. Food and Drug Administration (FDA) is primarily responsible for enforcing the Food Allergen Labeling and Consumer Protection Act of 2004, which requires that food labels clearly identify the food source names of any ingredients that are one of the major food allergens (including soy) or contain any protein derived from a major food allergen.

The law further explains that the name of the food source of a major food allergen must appear in parentheses following the name of the ingredient or next to the list of ingredients in a “contains” statement.

Unfortunately, the FALCPA’s labeling requirement does not apply to products that may be contaminated due to cross-contact. The FDA does not regulate statements such as: “may contain soy,” or “manufactured on shared equipment with soy” or “manufactured in the same facility as soy” so there is no guarantee that products labeled as such are safe.