Soybean consumption is increasing day by day and it is one of the widely used beans from the legume family. Soybean oil is one of the most common cooking oils used in India. Besides, the growing popularity of the vegan lifestyle is attracting people to adopt soy products in their daily diets. This changed food choice with soy is boosting the sales of soybean products like soy milk tofu etc as they are a common substitute for dairy products. 

Soy is now being used in a wide array of processed foods as a primary ingredient. However, there is a common allergy associated with the consumption of soy and its products. Avoiding soy is very difficult for people suffering from its allergy because it is present around us as food in various forms. 

Some common foods and ingredients that contain soy include:

• Various sauces and mayonnaise
• Artificial flavorings 
• Starches and broths
• Substitutes of meat
• Chicken nuggets and processed meat
• Frozen meals
• Some breakfast cereals
• Specific peanut butter

The root cause of soy-induced allergy is defined as the body’s immune system’s mistake in defense against the harmless proteins found in soy. The human body’s immune system mistakes it for invaders and releases substances called histamines, to protect the body. Such release causes an allergic reaction and each body reacts in a different manner.  

Soy is categorized as a ‘Big Eight’ allergen similar to cow’s milk, tree nuts, peanuts, wheat, eggs, and fish. Soy allergy is found to have developed in the human body at an early age. Children as young as three years are found with this allergy, however, most of it is resolved by the age of 10.

Symptoms of soy allergy

Different individuals react differently to soy allergy and the range varies from mild to severe. Some of the common symptoms include:

• Diarrhea
• Abdominal pain
• Runny nose
• Breathing trouble
• Wheezing
• Nausea
• Itchy mouth
• Swelling and itching
• Skin rashes
• In rare cases; anaphylactic shock

Identification of allergens in soy products

According to Detection and inactivation of allergens in soybeans: A brief review of recent research advances, published in  Grain & Oil Science and Technology (December 2021), “The main way to reduce allergy risk is the identification of allergenic sites in food and their inactivation by various food-processing methods. It has been reported that food processing may lead to the modification of the conformational structure of the protein or protein distortion that inhibits the binding of immunoglobulin E (IgE) to epitopes on food allergens and also the mechanism of allergic reactions. Food processing technologies employed for inactivating allergenic epitopes used thermal and nonthermal techniques”.

Testing and diagnosis of soy allergy

Soy allergy can be identified through various techniques and tests such as:

Skin prick test: Take a toothpick stick and scratch a portion of your skin, ideally on the inner side of the elbow. Apply the suspected allergen and observe the skin’s reaction. If a red bump or rash appears after some time, you are allergic to soy.

Intradermal skin test: In this technique, a large amount of allergen is injected into the body, so they reach the inner layers of the skin. It is similar to a skin-prick test, however, it gives detailed results.

The radioallergosorbent test (RAST): The RAST blood test is done to determine the amount of lgE antibody present in the blood. 

Food challenge test: The food challenge test is done in close observation of a doctor and physician. The suspected allergen is consumed in large quantities and the body’s reaction is taken into account.