Did you know that 1 in 15 young children in Canada have an allergy to at least one food? As a parent, introducing a food for the first time can be stressful. It’s impossible to know beforehand whether or not your child will be allergic to it.

This article will help give you some guidance if you’re unsure of how to go about introducing allergenic foods into your baby’s diet. We’ve outlined some advice on how to observe your child’s response to new foods and easily identify allergic reactions.

An allergic reaction to a food that is normally harmless happens because the immune system is overacting to the substance. It is trying to attack and defend itself. The substance (the “allergen”) is often a food protein. The immune system’s deregulated reaction to the allergen produces what we call an allergic reaction.

Food allergies and breastfeeding

Breast milk does not contain allergens, since it is perfectly suited to a baby. However, allergies can be caused by proteins from the mother’s food that pass through the breast milk. Luckily this is the case for less than 1% of infants.

Eliminating the food in question from the mother’s diet will stop the substance from passing through the breast milk. The baby will feel better as soon as this happens. Symptoms will return if the food is reintroduced in her diet.

Here are some of the most common signs of an allergy to a substance in the mother’s diet: refusal to nurse, diarrhea, constipation, blood in the stool, gastrointestinal discomfort (bloating, crying, squirming) for at least two to four hours, and gastroesophageal reflux (GERD).

While online advice suggests a breastfeeding elimination diet to root out the cause, it’s best to consult a doctor instead of self-diagnosing. It can be hard to tell whether the cause is an allergy that requires an elimination diet or if it’s gastroesophageal reflux (GERD), especially when the baby is crying a lot and the mom is tired. It’s best to note down all your child’s symptoms and consult with a doctor as soon as possible. A family nutritionist can help establish an elimination diet if necessary, or help the baby with reflux.

Food allergies and solids

For babies old enough to eat solids (around 6 months), food allergies can manifest directly after exposure, from several hours to several days after eating the food(s). These are called immediate or delayed allergic reactions.

Symptoms can be different each time there’s a reaction, and depend on the child. This means it’s impossible to predict how severe a reaction will be. An initial reaction might be mild, and subsequent reactions more severe.

A severe allergic reaction with rapid onset is called an anaphylactic reaction (or sometimes called anaphylactic shock). Anaphylactic shock is the most severe reaction and generally occurs rapidly following exposure, from a few minutes to two hours after eating a food. Anaphylaxis is rare, but can be life-threatening.

Call 911 if your baby develops hives and presents one or more of the following symptoms:

• Swelling of the lips, face, palate or tongue
• Difficulty swallowing
• Difficulty breathing (wheezing, shortness of breath, dry cough, swelling of the throat, change of tone of voice)
• Pale or bluish skin, itching
• Rapid change of general state (e.g., irritability, drowsiness, dizziness, loss of consciousness)
• Sudden vomiting—particularly projectile vomiting

This can mean your baby is having a severe allergic reaction. If you suspect your child has an allergy, you should speak to your doctor right away.

An allergic reaction that occurs several hours or days after your child eats a food can be trickier to identify. These milder symptoms can sometimes be confused with common discomforts.

Be on alert if your child becomes irritable, has diarrhea, nausea, or stomach pains in the time period from two hours to several days after ingesting a new food. Immediately stop feeding the food, and call 811 or your doctor.

Food allergy or food intolerance?

Food intolerance and food allergies are two different things. But it’s not always easy to tell the difference, since some of the symptoms are the same!

A food intolerance generally causes the digestive system to react. This happens when the digestive system is unable to digest or absorb a certain food or certain elements of that food. Unlike a food allergy, a food intolerance does not involve the immune system. So even though your child might be uncomfortable, an intolerance is not life-threatening.

The most common food intolerance in babies is lactose intolerance. Lactose intolerance is when an insufficient amount of lactase, an enzyme that normally allows our bodies to break down lactose (a sugar found in milk) is produced. Other common but less frequent intolerances include a sensitivity to gluten or food additives.

What should you do if you think your child has a food allergy?

If you suspect your child has a food allergy, speak with your doctor straight away.

If your baby has an allergic reaction, write down the foods eaten, the symptoms, and when the symptoms occurred. An allergist will use the information to decide on a course of action, reach a medical diagnosis if relevant, and ensure a follow-up with the right providers.

Priority allergens

Any food can, in theory, cause an allergic reaction. In practice, the data looks a bit different: the Canadian government has identified over 160 food as possible triggers for an allergic reaction. Health Canada’s list of key substances shows the culprits behind more than 95% of severe reactions. Here are the substances referred to as priority food allergens (or priority allergens):

• Eggs
• Milk
• Mustard
• Peanuts
• Molluscs and crustaceans
• Fish
• Sesame seeds
• Soy
• Sulphites
• Tree Nuts (almonds, Brazil nuts, cashews, hazelnuts, macadamia nuts, pecans, pine nuts, pistachio nuts and walnuts)
• Wheat and triticale

Prepackaged or processed food

Regulations under the Consumer Packaging and Labelling Act luckily make things easier for parents who have children with allergies (and parents who have allergies themselves!).

In Canada, allergens and gluten sources must always be clearly stated on a product’s labelling. This applies to ingredients and the components within individual ingredients.

Allergens can be found in the list of ingredients or in a “Contains” note directly underneath. However, if an allergen isn’t found in the ingredients, but the food may have been in contact with an allergen, the manufacturer is not required to declare it. The “May contain” note is a recommendation only.

Numerous studies have shown the benefits of introducing allergens into a baby’s diet very early on. Even more so if the child is at risk of developing a food allergy. Certain allergic reactions are even believed to be preventable through a complex biological mechanism called “food tolerance.”

Identifying children with a higher risk of food allergies

Certain babies and young children are at greater risk of developing food allergies. This can be true if:

• one of the parents or siblings has a food allergy or other type of allergy;
• the baby or one of the parents or siblings suffers from eczema, hives, asthma or hay fever; or
• the child already has another food allergy;

In these cases, be extra vigilant when introducing complementary foods at around 6 months of age.

Pregnancy and allergies

There is no reason to modify or restrict your diet in terms of allergy prevention during pregnancy (unless you have food allergies).

Breastfeeding and allergies

Breastfeeding is recommended for numerous reasons, including the fact that breast milk contains antibodies and other components that can help strengthen the baby’s immune system. Some research even demonstrates a link between exclusive breastfeeding during the first four to six months and a lower risk of food-allergy development.

A breastfed baby cannot be allergic to the mother’s milk, but can react to substances (proteins) which the mother ingests and then passes through her milk. (See the section on breastfed babies and allergic reactions.)

Bottle-feeding and allergies

When breastfeeding isn’t possible, hydrolyzed infant formulas are recommended for babies at risk of developing a food allergy. Speak with your doctor, or a pediatric nutritionist or nurse to help you choose the formula best suited for your child.

If you believe your baby is reacting to a protein in your breast milk or in the infant formula you’re using, it is helpful to keep a food diary of what your child is eating. This can help your health professional accurately diagnose the problem.

Foods and allergies

Conventional wisdom used to be that it was better to wait to introduce foods that commonly cause allergies. But, in fact, the opposite is true! Foods that commonly cause allergies should be introduced ideally around 6 months of age, but not before four months. This is especially important if the baby is at risk of developing a food allergy. Allergenic foods can be introduced in puree form starting at four months.

These foods can be introduced in the same way as other foods. You know your baby is ready to try solids when: they are able to sit up on their own, support and control their head, show an interest in food, able to pick up the food, put it in their mouth, and turn their head when they aren’t hungry anymore.

New foods should be introduced one at a time, for two to three days in a row. After the baby has been exposed to the new food for this time period, you can move onto the next one. Introducing foods one at a time allows you to see if they have an allergic reaction to it. Offer only a small amount at first, so your baby can taste the new food.

If your child seems to have no trouble with the new food, we recommend serving it three times per week to maintain tolerance, assuming the baby likes it and it’s part of your own eating habits. At the same time, they will be eating other less allergenic foods like vegetables, fruits, healthy proteins and whole-grain foods.

When a baby begins eating purees and solids, it’s essential that you keep track of what they’re eating in a notebook. This helps you remember when they last ate, what they ate, and how much. If a reaction occurs, your notebook will help you more easily find the cause and identify warning signs of the reaction.

Baby-led weaning

Baby-led weaning can be safely practiced as soon as the child reaches six months of age. Children at risk of allergy development can have allergenic foods introduced in puree form as of four months. Baby-led weaning can then begin as normal starting at six months.