How To Introduce Soy To Baby
Soy is one of the most common food allergens in children along with cow’s milk, egg, wheat, peanuts, tree nuts, fish, shellfish and sesame.
Introducing common food allergens early on in a child’s life (between 6-12 months) and continuing to offer them regularly reduces the risk of an allergy developing.
But, while introducing allergens such as cow’s milk and egg is relatively straightforward, soy can be a little more tricky as it’s a food many of us don’t regularly eat or offer to our babies and children.
So, if you’re wondering how to introduce soy to your baby, here’s what you need to know.
Soy allergy in babies and children
While soy is one of the most common food allergies, it’s less common than peanut, egg and cow’s milk allergies.
Soy allergy is usually seen in young children and the good news is most children will outgrow their soy allergy during childhood.
Like other allergies, soy allergy occurs when the immune system mistakenly identifies soy proteins as harmful. The body releases histamine to protect itself, and this histamine causes symptoms such as hives, coughing and vomiting.
There are two types of soy allergy, IgE mediated and non-IgE mediated.
IgE-mediated allergies are caused by IgE allergy antibodies, with reactions usually occurring within minutes of ingesting the food. Reactions typically include hives, vomiting and in more severe cases, anaphylaxis.
Non-IgE mediated food allergies are caused by a reaction involving other components of the immune system. Reactions take longer to appear and usually involve digestive symptoms such as vomiting, bloating and diarrhoea.
For more information on identifying food allergies in babies, see this fast facts about food allergy fact sheet.
When should soy be introduced?
Soy can be introduced whenever your baby starts solids. Most babies are ready for solids at around 6 months, but as all babies are different, it’s important to introduce solids when your baby is developmentally ready and showing signs of readiness, rather than going by their age alone.
Common allergens should be introduced early on, preferably before 12 months of age (but not before 4 months) as this has been found to decrease the risk of an allergy developing. This includes babies at high risk of allergy, for example, babies with an existing food allergy or eczema.
This is contrary to the old advice of delaying the introduction of allergens, which has since been found to actually increase the risk of allergies.
Once soy is introduced, continuing to serve it to your baby regularly - around twice per week - can help to maintain their tolerance.
Common sources of soy
Soy comes from soybeans which are a legume like peas, chickpeas, lentils and beans. Soybeans are sometimes eaten whole (for example as edamame - young soybeans) or processed and used to make foods such as tofu and tempeh, soy sauce, tamari and miso.
Soy is also used as a dairy alternative in products such as soy milk, soy infant formula and soy yoghurts and cheeses and is a common ingredient in many foods including:
Bread and other baked goods made using soy flour
Packaged sauces, flavourings and gravy mixes
Processed meats with filler such as chicken nuggets and hot dogs
Vegetarian and vegan meat alternatives
Foods containing soy lecithin (food additive 322) such as baked goods, sauces and chocolate (however, soy lecithin contains very little allergenic protein)
Soy is an ingredient in many types of bread
Is soy good for babies?
Soybeans are one of the best sources of plant-based proteins. It’s also a good source of plant-based omega-3 fatty acids and several vitamins and minerals such as choline, folate, iron and zinc.
Tofu can also be a good source of calcium, depending on how it is processed (i.e. calcium-set tofu).
However, some soy-containing foods are high in sodium, such as soy sauce and many meat-alternative products.
Soy and phyto-oestrogens
Soybeans naturally contain hormone-like substances called phytoestrogens. Given the right conditions, these compounds can mimic the action of the female hormone oestrogen, but they’re around 1000-10,000 times less powerful.
The type of phytoestrogens found in soy are called isoflavones.
Parents are often concerned about giving their baby soy or soy formula because of the potential effects of isoflavones. But soy and soy formula does not appear to be harmful to full-term babies with no significant long-term effects found in human studies.
However, infant soy formula may be harmful to premature babies and is not recommended.
If your baby is formula-fed, speak to your doctor or a paediatric dietitian about what formula is best for your baby.
Introducing allergens
Common food allergens should be introduced 2-3 days apart so you can more easily identify any foods your baby reacts to. They can be introduced in any order you like.
Introduce a new food only when your baby is well. As reactions to foods can take several hours to present, it’s best to introduce allergens at breakfast or lunchtime or when you can observe your baby for 2 hours after eating the new food.
If your baby is at high risk of a food allergy, that is, they have an existing food allergy or severe eczema, speak to your doctor before introducing common allergens.
Never rub food on your baby’s skin as a way of testing for a food allergy. This won’t help to identify a food allergy and can actually increase the risk of an allergy to that food developing.
For more information on introducing the 9 common food allergens, check out my Guide to Introducing Allergens.
Common food allergens
How to introduce soy
Ideas for introducing soy
There are a variety of different ways to introduce soy to your baby. Here are some ideas:
Stir silken tofu through fruit or vegetable puree or rice cereal
Cut silken tofu into cubes or offer it as a finger food
Mix plain soy yoghurt with fruit puree
Add soy milk to mashed or pureed fruit or vegetables
Offer a finger of toast made from bread containing soy flour (many regular breads contain soy flour - check the ingredients list on the label)
Try well-cooked edamame, mashed or squashed between thumb and forefinger (you can find edamame in the freezer section at the supermarket)
How to start
Start with a small amount - around 1/8 teaspoon, then, if no reaction occurs, double the amount each day until a normal serve of that food is reached.
Day 1: 1/8 teaspoon
Day 2: 1/4 teaspoon
Day 3: 1/2 teaspoon
Day 4: 1 teaspoon
Day 5: 2 teaspoons
Stop giving the soy-containing food if you think your child is having a reaction.
For more information on introduction of allergenic foods, check out this fact sheet from the Royal Children’s Hospital Melbourne.
How to tell if your baby is allergic to a food
Some allergies happen quickly and are easy to pick up, for example, swelling of the face, hives, a runny nose or vomiting. Others may be delayed and less obvious such as eczema, reflux, poor growth, diarrhoea and constipation.
Many food allergies in children are not severe and will resolve over time, but, some food allergies can be severe; causing life-threatening reactions known as anaphylaxis.
When monitoring for possible reactions, remember that the skin on your baby’s face is very sensitive and can be easily irritated by certain foods such as citrus, tomatoes and berries. These foods can cause redness on contact but this is not an allergic reaction.
What to do if your baby has a reaction
If you notice any swelling of the lips, eyes or face, hives or welts, vomiting or your baby comes very unsettled soon after giving a new food, they could be having an allergic reaction. You should stop feeding your baby that food and seek medical advice.
Call an ambulance immediately if there are signs of a severe allergic reaction (anaphylaxis), such as difficult/noisy breathing, your baby becomes pale and floppy, or there is tongue swelling.
The best treatment for an allergy is to avoid the food altogether. This can be tricky in the case of soy as it’s present in a wide range of foods. A paediatric dietitian can help with this.
More information on what to do if you think your baby is having an allergic reaction can be found here.
Soy foods to avoid
Not all soy foods are suitable for babies. Here are some that should be avoided:
Whole edamame beans - these are a choking hazard for babies. Edamame beans should be served mashed or squashed between thumb and forefinger
Soy sauce - due to its very high sodium content
Sweetened soy yoghurt - foods with added sugar are best avoided for babies
Can I give my baby soy milk?
Cow’s milk and plant-based milks aren’t suitable as a drink for babies under the age of 1 as they aren’t nutritionally adequate. Breast milk or infant formula are the only suitable drinks for babies under 12 months (plus a little water once solids are started).
However, once solids are started, babies can have small amounts of soy milk added to food, with cereal or used in cooking.
After the age of 1, babies can drink full-fat soy milk as long as they don’t have a soy allergy or intolerance.
Soy milk can be added to food or used in cooking but isn’t suitable as a drink for babies under 12 months.
Do I need to give my baby organic soy products?
It’s commonly believed that organic foods are more nutritious, safer, tastier and better for the environment, but this isn’t necessarily the case.
In particular, there is a lot of suspicion regarding the consumption of pesticides and cancer risk, but at the moment there’s not enough evidence of a definite link between the two. It’s also unclear whether the pesticides used in organic farming are actually safer than those used in conventional farming.
Claims that organic food is more nutritious have also not been proven. The nutrition content of food varies a lot whether it’s organic or not, and is dependent on the environment, season, climate, and freshness of the food.
Despite all of this, it’s understandable to be anxious about the potential effects of pesticides, particularly on our babies.
If you’re concerned about pesticides and can afford it, then organic produce may be worth the money. But the main goal is to offer your baby a wide variety of nutritious foods, so you may get greater health benefits overall by spending your money on more non-organic foods.
Allergies vs intolerances - what’s the difference?
Food intolerance is different to food allergy, as it doesn’t involve the immune system.
An allergy is an over-reaction of the body’s immune system to a foreign antibody, usually a protein (whether this be a protein in food, medication, insect bites, pet hair or dust etc).
Allergic reactions to foods may be immediate - occurring within minutes of eating the food - or delayed - occurring up to 48 hours after eating the food.
Food intolerance is more common than food allergy and occurs when there is a shortage of enzymes needed to digest a food (e.g. lactose intolerance results when there is a shortage of lactase enzyme) or an adverse reaction to chemicals in food.
These chemicals may be naturally occurring (e.g. salicylates or amines) or artificial (e.g. additives in processed food). The extent of the reaction usually depends on the amount of the food eaten – a small amount may cause no symptoms at all.
Food intolerance usually takes longer to present than food allergy and can present in a wide variety of ways including pain, irritability, poor sleep, wind, reflux, diarrhoea, mucous in poo, greenish or frothy poos, lethargy, eczema, refusing particular foods or refusing the breast or bottle.
For more information on introducing allergens, visit my Ultimate Guide to Introducing Allergens.
For more information on allergies, visit www.allergy.org.au or www.preventallergies.org.au/
