Introducing Allergens During Weaning

Blog written by Penny Barnard, Paediatric Dietitian, PhD RD Cert Allergy MBDA.

Weaning can be a daunting & anxious time for parents, especially when advice is changing and it is now recommended that common food allergens are introduced early, rather than late. The weaning process should be an enjoyable, happy & relaxed experience for both baby and parents. So, in this blog I will be discussing how to follow current weaning allergy advice with confidence.

Introducing Allergens During Weaning

Introducing Allergens during Weaning

For the general population the UK department of health recommends the introduction of solids from around 6 months of age alongside breastfeeding. For advice on starting weaning take a look at Charlotte’s blog and factsheets on first tastes. Once your baby has mastered first weaning foods such as vegetables, fruits & starchy food start introducing protein foods. If you baby is at higher risk of developing a food allergy (I discuss this further later on in the blog) then they may benefit from starting solids at closer to 4 months of age.

Before you begin to introduce solid foods here are a few general tips to consider when it comes to allergens:

  • Introduce each new allergen one at a time.
  • Start with a small amount of the new allergen, a quarter to half a teaspoon, and increase slowly over a few days.
  • Once the allergen is successfully introduced into the diet without a reaction include it in the diet regularly and by regularly I mean at least 1-2 a week depending on the allergen (I discuss this more later).
  • Only introduce a new allergen into your baby’s diet if they are well.
  • If your child has eczema it is best to ensure that their skin is in good condition before you introduce a new allergen. If emollients aren’t helping speak to your GP as soon as possible to maximise treatment of the eczema.
  • Always introduce the new food early in the day. Breakfast time or mid-morning is ideal or lunchtime at the latest. This will ensure you’ve got several hours during the day to monitor your baby for any reaction.
  • Do not rub food onto your babies lip or skin before allowing them to eat it. It is not a good way of testing if your baby has an allergy to a particular food.

What are the major food allergens in the UK?

There are 14 main allergens that I have listed below that are the most likely foods to trigger an allergic reaction across the whole of the UK population. By law these allergens have to be highlighted on an ingredients list on any pre-packaged foods you buy:

  • Cow’s milk
  • Egg (egg without the red lion stamp should not be eaten raw or lightly cooked in infants)
  • Cereals containing gluten, including wheat, rye, barley & oats.
  • Tree nuts (crushed, ground or a butter for children under 5 years).
  • Peanut (crushed, ground or a butter for children under 5 years).
  • Sesame
  • Soya
  • Shellfish (not to be served raw or lightly cooked for infants)
  • Fish
  • Mustard
  • Celery
  • Sulphur dioxide
  • Lupin
  • Molluscs (not to be served raw or lightly cooked for infants)

Other foods, such as kiwi, may cause an allergic reaction in little ones but they do not have to be highlighted on an ingredients list.


How many little ones in the UK have an allergy?

Before I start to talk about introducing allergens into LO’s diet let’s consider how many babies in the UK have a food allergy. Babies can experience reactions to food, but not all of these are true food allergy. In the UK around 5% of 0-2 year olds develop a proven food allergy. Symptoms of allergic reactions in very young children tend to be mild. Severe allergic reactions (called anaphylaxis) in children under 12 months is rare. No life-threatening reactions to date have been reported as a result of earlier introduction of potential allergens into the infant’s diet.

What food allergies are they more likely to develop?

The most common allergic reactions that occur in babies are to cow’s milk, egg, peanut, soya, wheat and fish (listed in order of most common to least common). The majority of non IgE food allergy (see below) is triggered by cow’s milk and IgE food allergy by egg.

Types of food allergy

Before I go any further let’s make sure we all know the difference between the two types of food allergy we see, IgE food allergy or ‘immediate food allergy’ and non IgE food allergy or’ delayed food allergy’ See the table below which describes typical symptoms of these types of allergy.

Which allergens do I introduce first?

Without too much thought or concern the first allergen that we offer to our little one on day one of life is milk. This should ideally be breast milk or if breast feeding is not possible a breast milk substitute (formula milk) should be offered.

Cow’s milk allergy (CMA) in babies who are exclusively breast fed is very low, less than 1 in every hundred. If your baby does show signs of a milk allergy when breastfed then breastfeeding should still continue. Mum should eliminate cow’s milk from her diet and take a suitable supplement containing calcium, vitamin D & iodine.

CMA is much more likely to occur in formula fed babies than breastfed babies. Formula milks in the UK are generally based on modified cow’s milk. The main proteins in cow’s milk are more likely to cause an allergic reaction. If your baby has been drinking formula milk with no problems the risk of developing an allergy to dairy when introduced into the diet is relatively low. However for breastfed babies the risk of developing an allergy to dairy products when introduced into the diet is greater. No added sugar yogurt or fromage frais can be offered or add fresh whole milk to meals such as porridge or mashed potatoes. See Charlotte’s website for further advice on this topic.

Why all the fuss about introducing allergic foods?

Over the past few years there has been increasing interest in when allergenic foods are introduced into LO’s diet and how this influences the likelihood of developing a food allergy. It is important to remember that nobody can tell you categorically (100%) if your child will develop a food allergy. They can only advise you, following an allergy focused history and possibly allergy tests, on the likelihood or probability of developing a food allergy.

Past advice for the avoidance & introduction of peanut

20 years ago when I was weaning my first child it was recommended that peanut was avoided during pregnancy & breastfeeding and not introduced as a first weaning food. In fact babies with eczema and existing food allergies such as a cow’s milk allergy were advised to avoid peanut until around three years of age. Over recent years this advice has been turned on its head and early weaning with peanut is now recommended. It is therefore not surprising that parents (and some healthcare professionals) are confused. So why has that been such a dramatic change of thought?

In the past decade 2 major studies in the UK have taken place that have influenced our current thinking about allergy prevention and led to new recommendations. The LEAP study (learning early about peanut allergy) looked at peanut introduction in babies who were considered at high risk of developing a peanut allergy. Secondly, the EAT study (enquiring about tolerance) looked at early allergen introduction in breastfed babies.


The results from these two studies have led to the following recommendations for the prevention of egg and peanut allergy. The recommendations fall into two categories; those infants with no risk factors for food allergy and those infants with a known risk factor for food allergy. A risk factor is eczema, especially early onset eczema or an existing a food allergy such as cow’s milk allergy. Infants with moderate – severe eczema are at greatest risk.

  • Babies with a known risk factor for food allergy should introduce cooked egg and then peanut alongside other solids early in the weaning process IF they are developmentally ready with support from a specialist. By early I mean from 4 months of age.
  • Babies with no risk factors for food allergy should introduce solids at around 6 months of age and include cooked egg and peanut along with other foods that are eaten as part of the families’ normal diet.
  • The deliberate exclusion or delayed introduction of specific allergenic foods may increase the risk of developing a food allergy to the same food.

How Do You Introduce Egg & Peanut into little ones diet?

Let’s talk about egg first

It is currently thought that egg should be introduced into the diet before peanut. Egg in its raw or lightly cooked form is far more likely to cause an allergic reaction than egg in the cooked and baked food. Raw egg should therefore never be given as first exposure to egg.  Give both egg white and yolk. Aim for at least 1 egg over the course of the week. At first this can be spread over the course of a week. As your LO gets older this can be offered in a meal in one sitting. At first hard-boiled egg can be whizzed in the food processor and mixed with purees of various vegetables, yogurt or rice. As baby learns to eat different textures it can be mashed & then chopped & added to foods. It can then be offered as a finger food or as scrambled egg and indeed you will have seen Raffy have boiled egg as part of his meal on many occasions.

Egg is such a versatile food & rich in nutrients. Once egg has been given as a first taste a few times & as your LO develops, egg in any form can be given (as long as it has the red lion stamp). If eggs without the red lion stamp are used they should be cooked all the way through.  Remember that raw egg is highly allergic so if given should be so cautiously. Charlotte & I have many recipes based on egg which we will share soon in another blog.

Here are a few ideas:

  • Vegetable omelette
  • Savoury muffin
  • Frittata
  • Pancakes
  • Savoury rice

If you find your LO dislikes or struggles with the texture of egg then do not despair. You can add egg to their diet in other ways. Here are a few suggestions:

  • Meatballs
  • Fish cakes
  • Potato cakes
  • Savoury slice
  • Goujons of fish or chicken

Now Let’s talk about peanut introduction

Children under the age of 5 years should not eat whole nuts. This has nothing to do with food allergy but due to them being a choking hazard. It can also be dangerous to offer peanut butter from the spoon as once again it can be a choking hazard as it can block the airways. Peanut can be added to the diet as flour, a butter or ground. An ideal way of introducing peanut is to use a smooth peanut butter with no added salt. It can be thinned down with a little breastmilk or water (1 teaspoon of peanut butter to 1 tablespoon of cooled boiled water). Alternatively it can be mixed with some vegetable or fruit, banana &sweet potato works well or porridge.

As your LO develops their feeding skills peanut can be added to other foods. Try adding it to breakfast cereal, porridge, yogurt, biscuits, savoury muffins, sauces, curry, casseroles and to coat fish or chicken. Look at Charlotte’s blog on porridge ideas as many of them contain nut butters. Peanut butter would work well with any of them. Check out our Instagram grid for recipes. Once introduced into the diet with no reactions aim for 2 level teaspoons in total throughout the week.

And lastly ……… introducing other allergen foods

I have talked about the introduction of cow’s milk, egg & peanut so to complete the weaning journey I will finish by discussing the introduction of other potentially allergenic foods if they are part of the family’s diet. Modify the texture dependant of your LO’s age and ability.

In Summary

I hope you have found this blog helpful and it has given you the confidence to offer your little one a mixed and varied diet. Here is a quick recap of the advice:

Written by:  Penny Barnard, Paediatric Dietitian, PhD RD Cert Allergy MBDA


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