By: Lauren Panoff, MPH, RD
Lauren specializes in plant-based living and vegan and vegetarian diets for all ages. She specializes in writing about parenting and a wide variety of health, environmental, and nutrition topics.
Soy is one of the top eight food allergens, affecting many children and adults. If you’re concerned that your child may have an allergy to soy, it’s important to be aware of which foods contain soy and how to design a soy-free diet. Understanding potential signs of a soy allergy and how to minimize exposure can help your child remain as symptom-free as possible.
What are the symptoms of a soy allergy or intolerance?
It’s important to differentiate between a soy intolerance symptoms in kids or soy sensitivity, and a true soy allergy. In order to determine which one your child has, it’s best to speak with their pediatrician for proper testing. That being said, below are some of the main differences and symptoms of both that may appear.
A soy allergy is when the immune system mistakenly sees soy proteins as foreign invaders in the body and creates immunoglobulin E, or IgE antibodies, to defend itself against them. Once these antibodies are made, the body recognizes whenever soy proteins enter the body and releases histamines in response. In other words, every time soy is consumed, the immune system initiates its attack response. This is what results in the symptoms of an allergic reaction.
Soy allergy reactions may have systemic effects on the skin, heart, digestive tract, or respiratory tract. It may cause symptoms like fussiness and diarrhea in infants, or even vomiting and hives in kids who are a bit older. Other potential symptoms include coughing, shortness of breath, wheezing, a weak pulse, or pale skin.
In rare but severe cases, soy allergy may lead to anaphylaxis. This is a reaction that is potentially life-threatening because it impairs breathing, can cause a severe drop in blood pressure, and may result in shock. Children with a severe soy allergy will likely be prescribed an epi-pen, or a dose of injectable epinephrine that can be administered to stop an allergic reaction in the event of an emergency.
Soy intolerance / Soy sensitivity
An intolerance or soy sensitivity, on the other hand, is not an immune response. An intolerance is generally less severe and often results in symptoms that mainly affect the digestive system, like nausea, abdominal cramping, and diarrhea. Still, a soy intolerance may initially appear in a similar way as a soy allergy, which can make it very difficult to differentiate between the two without an expert opinion.
Negative reactions to soy can appear either immediately after your child consumes it or hours after - similar to signs of lactose intolerance in kids. If you’re trying to determine if your child is having a reaction to soy foods, it can be helpful to keep a food journal that records the type and timing of symptoms as well as the food consumed.
How common is a soy allergy?
Soy is one of the top eight food allergens, which make up over 90% of all food allergies. The other allergens in this group include cow’s milk, fish, shellfish, wheat, tree nuts, peanuts, and eggs.
An allergy to soy commonly begins early on in infancy or toddlerhood. Only a small amount (an estimated 15%) of babies who have cow’s milk allergies are also allergic to soy. While many children will continue to experience a soy allergy for life, others may outgrow it around age ten. Read through our guide on treating toddler seasonal allergies to see if that can be a factor as well
Interestingly, it’s uncommon for an individual to be allergic to soy and nothing else. In other words, if your child has a soy allergy, it’s possible that they may have an allergy to other foods or ingredients. This may be worth exploring particularly if you have a family history of food allergies.
Note that the biggest way in which having a soy allergy may impact a child’s health is because of the risk of being exposed to soy through so many foods and other consumer products. While soy is an excellent source of protein and other nutrients, there are plenty of other foods to help make sure that your child received a healthy and adequate diet.
How do you test for a soy allergy?
It’s best for your pediatrician to work with you to navigate diagnostic testing for a soy allergy, which is most often conducted in conjunction with an allergist.
Some of the most commonly used tests to identify and confirm food allergies, like a soy allergy, include the following:
- Intradermal skin test: In this test, an allergen is injected underneath the skin using a syringe. If a soy allergy is present, a noticeable reaction will be observed.
- Skin prick test: This test uses a smaller amount of the allergen in question than the intradermal skin test. Instead, the allergen is placed directly on the skin, and then a needle is used to poke a tiny entry point into the outside layer of skin. A small red bump will form in response to the allergen if a soy allergy is present.
- Radioallergosorbent test: Also called a RAST, this is a blood test that can be done in very young babies who may not tolerate or respond well to the skin tests listed above. This test measures how much IgE antibody is present in the blood, which will tell the specialist whether there is an allergy to the particular compound in question.
- Food challenge: In a food challenge, your child will be given soy in increasing amounts under controlled and observed conditions. Direct observation with the doctor will make sure that any alarming response symptoms are appropriately treated.
- Elimination diet: This approach is similar to elimination diets prescribed to adults. Soy, and all foods containing soy-derived ingredients, will be completely removed from your child’s diet for a prescribed amount of time. Then, it will be gradually added back to their diet in a calculated and intentional way. Response symptoms will be observed to identify if soy is a problem and if so, which soy foods and ingredients are the worst offenders.
How to test for a soy allergy at home
It’s not recommended to intentionally test for food allergens at home, due to the potentially life-threatening nature of food allergies among some children. Food allergies can range in their severity and should be treated with caution, especially when you’re uncertain whether your child has one. Testing for a food allergy should be done under the direct supervision of an expert clinician as discussed above.
However, if you notice that your child is having an adverse reaction to soy or soy-containing foods, this could certainly be an indication of an allergy. If this occurs, make an appointment with your pediatrician as soon as possible. This will help make sure that your child has the proper testing to identify a soy allergy or sensitivity, and then you can make an appropriate plan going forward.
Which foods contain soy?
Soy can be a difficult ingredient to avoid for people who are allergic to it. This is because, while whole soy foods are more obvious and easier to avoid, processed soy and soy-derived ingredients are used in a wide variety of packaged foods.
Soy foods in their whole or minimally processed form include tofu, tempeh, natto, miso edamame, and soy milk. More processed soy foods may include other traditionally dairy-based foods made with soy such as ice cream, yogurt, cheese, butter, sour cream, and certain dressings or condiments.
One example of a common soy-derived ingredient is soy lecithin. This is a food additive found in many packaged food items. It serves as an emulsifying agent, which helps increase shelf life for some products, prevents spattering of certain foods when heated in oil, and can prevent chocolate candy from crystallizing. Still, it doesn’t generally contain enough of the soy protein that causes allergies in people, so it’s possible that this may not be a trigger for your child even if she has a soy allergy.
The bottom line here is that, in addition to whole soy foods, many packaged and processed foods may contain soy in the form of food additives.
Soy allergy foods to avoid
If a child is allergic to soy, it’s important to be aware of which foods to avoid that may be common in many households. Having a “soy allergy foods to avoid list” can be helpful to place on your refrigerator or take with you to the grocery store until you get the hang of shopping soy-free.
Fortunately, there is a law called the The Food Allergen Labeling and Consumer Protection Act (FALCPA) that requires that packaged foods in the United States have a statement on them that clearly indicate they may contain soy or an ingredient that contains soy. This can be helpful, but having an awareness of common soy-containing foods is even better when planning a soy-free diet for your child.
But because soy is so common used as an ingredient, it’s frequently found in packaged foods such as:
- Peanut butter
- Breakfast cereal
- Asian condiments
- Worcestershire sauce
- Vegetable-based broths
- Plant-based meat alternatives (e.g., deli slices, hot dogs, burgers)
- Frozen meals
- Processed and frozen meat products
The best way to avoid soy as an ingredient in common foods is to make a habit of reading the ingredient list on packages and containers.
Soy used as a food additive ingredient may be listed as a number of things on packaged foods. For example, it’s probably best to avoid foods that contain any of the ingredients listed below if your child has a soy allergy:
- Hydrolyzed soy protein
- Textured vegetable protein (TVP)
- Soy fiber
- Soy flour
- Soy yogurt
- Soy albumin
- Soy milk
- Soy curp
- Soy granules
- Soy sprouts
- Soy protein isolate
- Soy protein concentrate
- Soy sauce
Have you ever noticed that packaged foods often contain “natural flavorings” listed on the ingredients list? This is very common and unfortunately, it’s impossible to know what’s included in this unless you contact the manufacturer directly. If you choose to do so, you should ask them whether soy was used as a carrier protein to make their natural flavorings. While they likely won’t tell you what’s in their natural flavoring, they should be able to answer this simple question.
You may also want to contact a company directly if they have vegetable broths, gums, or starches listed on their product as these may contain soy.
Furthermore, foods that don’t intentionally contain soy can still come with the risk of having been cross-contaminated with soy during their processing. Many manufacturers choose to include warning statements on products, such as "processed in a facility that also processed soy,” or indicating that the product could contain common food allergens by accident. However, these statements are voluntary, so it’s best to choose foods that are at the lowest risk of containing soy in the first place.
Soy-free foods list
Now that you know some of the major foods to avoid with a soy allergy, it can also be incredibly helpful to have a list of foods that are generally soy-free. It’s still a good practice to read ingredient labels in these instances to make sure they are truly soy-free, as that’s the only way to know for sure.
First, if you have an infant who is diagnosed with a soy allergy and is formula-fed, it’s appropriate to choose a soy free formula, such as a hypoallergenic option. These types of baby formulas contain proteins that have been extensively broken down so that they present a lower risk of triggering an allergic reaction. Elemental infant formulas contain proteins in their simplest, most digestible and least risky forms when it comes to allergic triggers.
For older babies and children who are eating solid foods, here are some soy-free staple foods to keep in mind when planning their diet:
Breads and starch foods:
- Breads, cereals, and baked goods that don’t contain soy in the ingredients list
- Snacks that don’t contain soy or are cooked in soy oil
- Plain pastas made from wheat, lentils, or beans that are not soy-based
Plant-based milks, cheeses, and dairy products made from:
- All fresh fruits and vegetables that are not soybeans
- All frozen plain fruits and vegetables that are not edamame or soybeans
- All canned fruits and vegetables that are not soybeans or contain soy on the ingredients list
Protein and meat substitutes:
- Other meat analogues that are not tofu, tempeh, and don’t contain soy on the ingredients list
Fats and oils:
- Nut butters made from peanuts, cashews, almonds, or sesame seeds and don’t contain soy on the ingredients list
- Butters and margarines that are soy-free
- Vegetable oils that are soy-free, such as olive, avocado, flax, and coconut
Remember that even though having a child with a soy allergy can feel overwhelming at first, it won’t always feel that way. Having the right diagnosis is the first step to managing a soy allergy, followed by a plan for practicing a soy-free diet pattern and knowing which foods to avoid. Fortunately, there are a growing variety of soy-free plant-based foods available today that can be an excellent part of your child’s diet.
Try Else for soy allergies
Else formula has been designed to offer comprehensive nutrition to children who need soy-free options. Else products are formulated with organic almonds, tapioca, and buckwheat, are hypoallergenic and completely plant-based.
Not only are Else formulas free from soy, they’re also free from dairy, gluten, GMOs, and corn syrup, which are often found in other infant and toddler formulas. Whether your child needs a soy-free formula or meal supplement, or you’re just looking for a nutritious plant-based option, Else Nutrition products have been designed with your family in mind.
Having a soy allergy is common, especially among young children. While some kids will grow out of their soy allergy within the first decade of life, that’s not the case for everyone. Properly identifying, testing, and diagnosing a soy allergy is imperative for proper management.
For children with soy allergies, choosing soy-free infant formulas and following a diet that excludes soy is the best approach. Additionally, Else Nutrition products can be a helpful and nutrient-rich addition to your child’s soy-free diet.
The content and advice provided in this article is for informational purposes only and is not a substitute for medical diagnosis, treatment, advice for specific medical conditions. Always consult a pediatrician to understand the individual needs of your child.