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Introducing Common Food Allergens Safely During Weaning

07 July 2022 Written by Lucy Upton

Lucy Upton talks about exploring food allergens safely during weaning.

Food allergies are something many parents find themselves worrying about, particularly during weaning as babies start to be introduced to foods more commonly associated with food allergy reactions. It is especially common to hear concerns from parents where food allergy already exists in the family, or when a baby has a food allergy already e.g. Cow’s Milk Protein Allergy.

Whilst it can often feel easy to shy away from introducing these foods or just ‘leave it until next week’, scientific evidence pulled from lots of studies completed here in the UK has highlighted, more than ever, the importance of getting common food allergens early! Early and proactive introduction during weaning has been found to reduce the risk of your baby developing food allergies. Gone are the days when you should be delaying introducing these foods until your baby is 2, 3, 4 or 5 years old!

What are the common food allergens?

In the UK, there are 9 key foods that we know are most likely to cause allergic reactions. These are listed below:

  1. Cow’s milk
  2. Egg
  3. Foods that contain gluten, including wheat, barley & rye
  4. Soya
  5. Fish
  6. Shellfish
  7. Sesame and other seeds
  8. Peanuts (actually a legume, not a nut!)
  9. Tree nuts e.g. almond, pistachio, hazelnut, macadamia, pecan, cashew, brazil, walnut

It’s worth being aware that you can be allergic to any food, however, over 90% of the reactions we see in the UK are to foods are to the allergens outlined above.

Is there a difference between food allergy and intolerance?

The short answer to this is yes!  Despite the fact food intolerance is often used interchangeably with allergy, they are very different – even though some symptoms can cross over.

  • Food allergy is a response to a food protein driven by the body’s immune system. This means that every time a child or individual is exposed to that food allergen, the immune system kicks into action.  Food allergy symptoms can be immediate (often within minutes to 2 hours) or delayed (2-72 hours later). In the case of immediate symptoms, these can be life-threatening and cause difficulty breathing and collapse – severe reactions like this are referred to as anaphylaxis 
  • Food intolerance is not an immune response, and symptoms can never be life-threatening.  Symptoms can also vary depending on how much of the culprit food is consumed. Food intolerance symptoms often are gut and/or skin-related and are often related to difficulty with the digestion of a certain food component or sensitivity to a naturally occurring substance in the food.  A good example of food intolerance is lactose intolerance. This is often mistaken as cow’s milk protein allergy, however, is actually a condition where the body is unable to digest the lactose (sugar in milk) due to a lack of the enzyme in the gut that breaks down lactose.

When should you be introducing these food allergens?

Parents are encouraged to now introduce these foods safely to babies from the start of weaning.  For most babies, who would be considered at low risk of developing food allergy, this means that allergens will be introduced from around 6 months of age. Babies should be developmentally ready for weaning, and will probably have introduced some first foods before allergens start to be introduced.

There are however a group of babies who would be considered to be at a higher risk of developing food allergies. Current research has identified that this group of children may benefit from the early introduction (between 4-6 months of age) to these common food allergens, particularly egg and peanut – BSACI’s Paediatric Allergy Group. This should ideally be with the support of a Health Professional such as a Dietitian.  Babies considered at elevated risk of developing food allergies are those who;

  1. Already have a diagnosed food allergy – most commonly this is Cow’s Milk Protein Allergy which is often diagnosed < 6 months of age /  and/or
  2. Have eczema, particularly if this is considered moderate to severe e.g. requires a daily steroid cream, early onset in the first few months of life, worsening or persisting in nature

If you or a member of your family has a food allergy this does not place your child within this higher risk category at present, and it can be reassuring to hear that a family food allergy doesn’t necessarily increase the risk of a child directly inheriting that same food allergy. It is recognised that a family history of atopic disease (eczema, hay fever, food allergy or asthma) can be associated with an increase in the risk of a child also developing an atopic condition, a present the advice is to actively introduce food allergens from weaning age, in line with general population advice.

Eczema is now well established as a risk factor for developing food allergy and is understood to be the reason why babies may react to a food allergen on the first exposure via their diet.

This can be explained simply below:

  • To react to a food, the immune system needs to have been exposed to it at least once already. This is why some babies may react to a food, but only from the second time, they have eaten it.
  • For babies with eczema, it is thought that the first exposure to a food protein (which they may later develop an allergy to), is via the skin.  The skin is often our body’s first defence and protection from harmful bugs and bacteria.  In babies who therefore have a damaged skin barrier, due to eczema, food proteins reach the skin e.g. from our hands, the atmosphere and the immune system trigger a defence (rather than ‘this is safe’) response to the body.  This then leads to later presentation with food allergy, which becomes apparent when a baby is introduced to the food during weaning.  This is why we aim to introduce the food allergens early, via the gut e.g. in food – the gut can recognise food proteins as safe and meant to be there, rather than harmful

*Ideally alongside maintenance of breastfeeding – mothers should continue to breastfeed whilst introducing solids wherever possible as this may also support the baby’s development of tolerance to new foods.

If your baby fits in the higher risk bracket, please seek support from a health professional who has experience with managing food allergies, about the best time to introduce these foods. Whilst your baby is considered at higher risk of developing food allergy, they also fall into the group who would be likely to benefit most from allergy prevention advice.  

How can you safely introduce each food allergen?

Based on current evidence, it is currently recommended to introduce egg and then peanut first. Especially for babies at increased risk of food allergy (see above). Following this, the order you choose to introduce each food is completely up to you. Throughout the allergen introduction process, you can continue to include foods your baby has had before. In the table below there are some examples of how you might introduce each common allergen, followed by advice about how to build this up slowly. Always offer foods in a safe, age-appropriate form.  

Food Allergen Food Options

Include the yolk & white

*Choose lion stamped eggs

  • Hard-boiled egg
  • Omelette strips 
  • Well cooked scrambled eggs
  • Egg muffins

​​Do not give chunky peanut butter or undiluted smooth peanut butter directly off a spoon, as these can pose a choking risk.  Whole or coarsely ground or chopped peanuts should also be avoided for the same reason, in babies and children under 5 years.

  • Smooth 100% peanut butter (Loosen with a little warm water or milk if needed)
  • Well ground unsalted peanuts (dust consistency)
  • Puffed peanut snacks
Cow’s Milk
  • Plain yoghurt or fromage frais (e.g. natural or greek yoghurt)
  • Whole cow’s milk in a meal e.g. cereal, white sauce, mashed potato
  • Unsweetened soy yoghurt or milk alternative
  • Tofu – blended or as a finger food

*Note many breads contain soy flour which can also be a way of initially introducing soya

  • Wheat-based cereals e.g. wheat biscuits 
  • Soft cooked pasta pieces
  • Bread e.g. toast fingers
  • Flaked or blended fish
  • Fish mashed into fishcakes

Always ensure shellfish is well cooked

  • Finely chopped or minced prawns
  • Flaked, blended or mashed crab meat

*choose shellfish you would normally eat at home*

  • Tahini (smooth sesame paste) – may need loosening with water or milk
  • Hummus – often contains tahini (be mindful of salt content)
Tree Nuts

Do not offer your baby or child (<5 years) whole nuts or coarsely ground or chopped nuts as these post a choking risk

  • Smooth 100% nut butter e.g. almond, cashew butter
  • Finely ground tree-nuts – dust or ground almond consistency

Where necessary e.g. when the allergen cannot be or isn’t accepted on its own, combine with something your baby has had before. For example

  • Combine mashed or blended hard-boiled egg into a well-accepted vegetable
  • Add peanut butter to baby porridge or pureed or mashed fruit.

Top tip – Once you have successfully introduced your baby to a food allergen, aim to keep it in their diet! Offer early, given often e.g. at least weekly. For example, you could include eggs as savoury muffins, omelette fingers, eggy bread or mix well-cooked scrambled egg with some Kid’s Tilda Rice for an egg-fried rice dish!

Guidance on introducing food allergens safely

To support safely introducing food allergens to your baby

  • Allergy symptoms – Familiarise yourself with the signs and symptoms of an allergic reaction. This will help you feel confident in recognising any immediate or delayed symptoms. A detailed list of symptoms can be found on the NHS website and/or Allergy UK website.  It can be reassuring to hear that severe reactions are very rare.

If you think your baby is having an allergic reaction or symptoms after being offered food you must always stop giving that food and seek medical advice immediately 

  • One at a time – Always introduce one food allergen at a time, alongside your baby’s normal weaning foods.  If more than one is introduced at once and your child develops symptoms it can be difficult to work out which food caused the reaction
  • Earlier in the day – Consider offering allergenic foods early in the day e.g. morning to allow for more time to monitor for symptoms
  • Start slow – Begin by offering very small amounts of a food allergen e.g. ¼ teaspoon. You can then gradually increase the amount offered each time e.g. ½ teaspoon, full teaspoon
  • Your baby’s health – Ideally, your baby should be in good health and not currently ill or recovering from illness when first introducing these foods. If your baby has eczema, it’s a good idea to have this as well controlled as possible prior to introducing allergens. 
  • If you are feeling nervous –  aim to introduce these foods at a time when another member of the family is around for support
  • Don’t force – if your baby refuses to eat a food allergen, don’t panic and certainly don’t force them.  Try again by offering the same allergen at another time, and consider offering in a portion of different food, or one that has been previously very well accepted.

Tracking – you may find keeping a diary or planner to monitor the introduction of these foods helpful. If you do suspect a food allergy reaction, keep a note of the time of reaction, how quickly it appeared, what your baby had eaten, and symptoms (including pictures) to take to your Health Professional

What about skin rashes? 

Skin reactions during weaning are actually a common occurrence and not all are food allergy-related. During weaning, some babies can develop what’s known as a contact reaction or contact dermatitis to food.  This is where the food being eaten causes localised redness and irritation to a baby’s skin, often where the food has touched the skin e.g. face, cheeks, neck, hands.  These reactions can be more pronounced in babies who already have skin conditions such as eczema. In such circumstances, the skin rash will not spread, will not be alongside any other common allergy symptoms, cause little to no discomfort for the baby and usually self-resolves very quickly.

Common triggers for contact-based reactions include;

  • Acidic foods e.g. citrus fruits, tomatoes, or foods that use lemon juice for preservatives
  • Histamine-rich foods e.g. aubergine, banana, avocado, spinach

For more information on food allergies in children, and introduction to food allergens during weaning you can visit: