Cow’s Milk Allergy is one of the most common food allergies in early childhood and affects 2-3% of all infants. According to Prof. Christophe Dupont, President of the French Society of Pediatrics’ Committee of Nutrition, cow milk allergy can result from a type of skin malfunction and sensitisation in early life. In fact, both food allergy and eczema develop at the same age, in the first months of life, which leads researchers to think they could be linked. Also, milk allergy is associated with gastroesophageal reflux, so much so that around 40% of gastroesophageal reflux cases in children are related to cow milk allergy.

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The Development of Food Allergies

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For an allergy to develop, the body is first exposed to an allergen that it considers harmful, which triggers a process called sensitisation. If the body encounters this allergen again, antibodies capture it and immune cells release a set of chemical substances such as histamines, which are responsible for symptoms such as itchiness, inflammation, etc. Food and milk allergies originate from the development of early eczema, a skin defect caused by the malfunctioning of filaggrin.

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Filaggrin is a major structural protein located in the outer layer of the skin. Its primary function is to seal the skin barrier’s structural proteins together and form tight stacks which flatten and strengthen cells for a stronger barrier that keeps external threats from penetrating the body (infections, chemicals, toxins and allergens). Mutations in the filaggrin gene have shown to be a predominant genetic risk factor for the development of allergic diseases. Approximately 10% of people carry filaggrin mutations.

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The malfunctioning of filaggrin affects the skin barrier by disrupting its protective function and causing openings that allow allergens to enter and reach the antigen cell that triggers sensitisation. When babies grow up, the malfunctioning of filaggrin is resolved by a compensation mechanism, but the sensitisation persists, triggering the same symptomatic reaction when re-exposed to the allergen.

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Types of Food Allergies

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There are three types of food allergies :

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• IgE-mediated allergies are mediated by a type of antibody called immunoglobin E which causes an allergic reaction within minutes of ingestion.

• Non-IgE-mediated allergies are caused by a reaction to other components of the immune system, but not the immunoglobin E.

• Eosinophilic oesophagitis (EoE) is a chronic allergic and immune condition of the oesophagus related to IgE-mediated and non-IgE-mediated allergies.

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Some foods such as milk, soy, egg, and wheat allergens can trigger any type of allergy, whereas others such as peanuts, tree nuts, kiwi fruits and sesame are IgE-mediated only. IgE-mediated milk allergy can cause hives, abdominal pain, vomiting, diarrhea, rhinitis, asthma and in the most severe cases, angioedema and anaphylactic shock. However, non-IgE-mediated milk allergy symptoms are the most common in newborns and babies, including colic, reflux, abdominal pain, irritability, constipation, diarrhea, atopic dermatitis, and asthma.

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Eosinophilicesophagitis (EoE) is closely related to cow milk allergy which presents itself almost as an eczema in the esophagus and can cause severe reflux in infants.75% of Eosinophilic Esophagitis cases are linked to cow milk.

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Detecting Cow’s Milk Allergy

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If you suspect your child may have cow’s milk allergy, consult your doctor. They may suggest a skin prick test if they suspect it is IgE-mediated or an atopy patch test fornon-IgE-mediated cow milk allergy. In early life, detecting and putting in place a follow-up plan for cow’s milk allergy is essential as, unlike other types of food allergies, it has been shown to impact growth.

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Feeding an Infant or Child with Cow’s Milk Allergy

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In milk allergic babies, feeding adapted formulas is recommended to avoid any nutritional deficiencies. Whereas regular formulas use raw milk proteins (that have not been baked), these formulas are made with tiny portions of milk proteins that are extracted and baked so that they will no longer be allergenic. These are usually perfectly adapted to children with cow’s milk allergy. However, they still contain minimal milk remnants, and so for very allergic children, it is best to opt for formulas where the milk proteins have been replaced. Breastfed babies can also suffer from cow milk allergy, and so breastfeeding mothers should eliminate cow milk from their diet.

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Improving Tolerance to CowMilk

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Your healthcare professional will likely advise you to implement an elimination diet. This will require you to eliminate any form of cow’s milk protein from your child’s diet (such as raw milk, butter, cheese, yoghurt, etc) and any type of cooked food containing milk (such as biscuits). The elimination diet usually last several weeks and aims to evaluate your child’s tolerance to specific amounts and milk-based foods. Then, they will recommend an oral food challenge, where under medical supervision, your baby will be fed small amounts of milk-based products to evaluate tolerance.

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Prof. Christophe Dupont suggests it is important to identify whether your child is allergic to foods containing baked milk by feeding them milk-based biscuits, for example. Heexplains that baked milk is key to improving milk tolerance which can be done by introducing increasingly more and more foods containing baked milk into their diet. Also, consider usingthe Milk Ladder, which is extremely useful in helping parents monitor the kind of product they can use to help a child go back to a regular diet. You should start with foods containing very low milk quantities, evaluate the tolerance, and advance in the ladder if the tolerance is good. Tolerance testing and allergen re-introduction should be done by following your healthcare professional’s recommendations.

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References

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1. Webinar on Cow’s Milk Allergy by Prof. Christophe Dupont

2. Milk Ladder

3. The Multifunctional Role of Filaggrin in Allergic Skin Disease

4. FLG Gene

5. Filaggrin failure – from ichthyosis vulgaris to atopic eczema and beyond

6. Cow’s Milk Elimination Diet – Where to Start

7. Elimination and challenge

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