What is a soy allergy?
Soy products come from the soybean. An allergy to soy occurs when the body reacts to one or more of the proteins in soybeans.
How serious is a soy allergy?
The soybean is a nutritious vegetable that can be made into tofu, soy milk, soy flour and much more. It rarely causes anaphylaxis, but its use in so many food products makes a serious reaction more likely.
Soy is one of the most common foods that cause an allergic reaction. Those with a soy allergy must avoid all soy products and all soy ingredients.
Milk and soy allergies
Some infants develop an allergy to both milk and soy. If an infant is allergic to milk and soy, they will need to start on a hypoallergenic formula and continue taking it even after they start solid foods. The hypoallergenic formula contains proteins that are already broken down. This helps infants to digest the formula without having an allergic reaction.
Brands of hypoallergenic formula include Alimentum, Nutramigen and Pregestimil, but these are suggested formulas only. If your child has a milk or soy allergy, speak with your doctor or dietitian before deciding which formula to use.
Other names for soy
Soy can have many names in ingredient lists. Learning these names can help you catch any hidden sources of soy in food.
When buying packaged foods, always check the list of ingredients in the store and again when you bring the product home. It is also a good idea to check the ingredients every time you buy the food in case the recipe has changed. You can also call the manufacturer to ask about any recipe changes.
The following table lists some of the names for soy. Use it when you are grocery shopping or calling food manufacturers.
| Edamame | Miso | Mono-diglyceride |
| Natto | Okara | Soya, soja, soybean, soyabean |
| Soy protein (isolate/concentrate) | Tempeh | Textured vegetable protein (TVP) or vegetable protein - soy may be the source of protein |
| Tofu (soybean curds) | Yuba |
Possible sources of soy
Soy is used in a range of packaged foods. Below is a list of some of the many food products that contain soy.
| Baby formula | Baked goods and baking mixes (including bread, cookies, cake mixes, donuts or pancakes) |
| Bean sprouts | Bread crumbs, cereals or crackers |
| Breaded foods | Canned tuna |
| Chewing gum | Cooking spray, margarine and vegetable shortening/oil |
| Dressings, gravies, marinades | Frozen desserts |
| Hydrolyzed plant protein (HPP), hydrolyzed soy protein (HSP) or hydrolyzed vegetable protein (HVP) - may contain soy, wheat, corn or peanut as the source of protein | Lecithin, a food additive that acts to emulsify foods or keep them from spoiling – can be made from soybeans, eggs or corn (call the manufacturer if soy is not stated) |
| Monosodium glutamate (MSG) | Peanut butter |
| Sauces (soy, teriyaki, Worcestershire) | Seafood-based products |
| Seasonings, spices | Snack foods - candy, chocolate, fudge, popcorn, potato chips |
| Soups, broths, soup mixes, stews, stock | Soybean oil - highly refined oil is considered safe because the soy protein has been removed, but it is still best to avoid it, especially if it is a main ingredient |
| Spreads and dips | Textured soy flour (TSF) |
| Textured soy protein (TSP) | Vegetarian packaged dishes |
What do I do if my child has a soy allergy?
Your child should see an allergist (a doctor who specializes in diagnosing and treating allergies) who can discuss the soy allergy with you in more detail. Children who have a soy allergy should avoid all products that may contain soy.
Your child’s doctor may also prescribe a medication called an epinephrine auto-injector, which can be used to treat allergic reactions, in case your child accidentally eats a food containing soy.
Reducing the risk of cross-contamination
Cross-contamination occurs when one substance unintentionally comes in contact with another substance, for example a potential allergen. If the substances mix together, one substance taints the other substance, making it unsafe to eat.
Food allergens can contaminate other foods when, for example, the same containers, utensils or frying pans hold a range of foods.
Bulk food containers pose a high risk of cross-contamination because they are often used for different products.
Be sure to avoid using utensils or containers that may have come in contact with allergy-causing foods and ask about possible cross-contamination when eating out.
How can my child get the right mix of nutrients if they must avoid soy?
The main nutrients in soy include protein, omega-3 fatty acids, folate, iron, calcium, vitamin D, zinc, fibre and B vitamins. Your child can still get these nutrients even if they must avoid soy.
Nutrients in soy that are found in other foods
| Nutrient | Where to find it |
|---|---|
| Protein | Meat, fish, poultry, cheese, milk, egg |
| Omega-3 | Salmon, tuna, mackerel, walnuts, ground flax seeds, canola oil, omega-3 fortified eggs, whole grain bread, cow's milk |
| Folate | Leafy green vegetables, beans (navy, pinto, kidney, garbanzo), lentils |
| Iron | Meat, shrimp, poultry, beans (navy, pinto, kidney, garbanzo), whole wheat products, green leafy vegetables |
| Calcium | Cow's milk, cheese, yogurt, calcium fortified orange juice, broccoli, salmon with bones, almonds |
| Vitamin D | Fortified margarine, salmon, egg yolk, cow's milk |
| Zinc | Meat, fish, poultry, whole grains, vegetables |
| Fibre | Whole grains, fruits, vegetables |
| B vitamins | Whole grain bread, cereal, pasta, rice |
When to see a dietitian for a soy allergy
If you have removed many foods from your child's diet because of a soy allergy, it may be a good idea to speak to a registered dietitian. The dietitian can review the foods your child still eats to decide if they are getting enough nutrients. If necessary, they can also recommend alternative foods that your child can eat safely.
Will my child always have a soy allergy?
A soy allergy is most common in infancy. Many children with a soy allergy outgrow it as they get older. An allergist can help you find out when to test your child and see whether they have outgrown their allergy.
Top 8: What are the most common allergies in kids?
For more videos from SickKids experts in collaboration with Youngster, visit Youngster on YouTube.
When to go to the emergency room
If your child is having a severe allergic reaction to soy, call 911 or go to your nearest emergency department immediately. If your child’s doctor prescribed them an epinephrine autoinjector, administer this medication to your child right away. See Anaphylaxis: How to recognize and respond to a severe allergic reaction for more information.
Further information
Health Canada. Soy - A priority food allergen