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Renowned specialist paediatric allergy dietitian, Dr Carina Venter, has compiled this feature on the myths and reality of CMA in infants to help dispel popular misconceptions surrounding the condition. We hope the key facts included will give you a better understanding of CMA and help you to recognise and manage the symptoms more effectively.
Allergic reactions to foods, including cows’ milk, can appear within minutes to days. Quick onset allergic reactions can appear within seconds and up to 2 hours after ingestion and are referred to as IgE-mediated allergies.* The more delayed onset food allergies usually appear after 2 hours, can take hours to days to develop, and are referred to as non-IgE (Immunoglobulin E ) food allergies1.
Key message: cows’ milk allergy (CMA) can present with a wide range of symptoms, appearing over a range of times.
* Respiratory symptoms appear in conjunction with other symptoms but not as a single symptom of food allergy.
A positive skin prick test or blood test can be predictive of a food allergy, however these tests can sometimes yield a “false positive” result2,3. An oral food challenge is the most definitive test to determine whether your child has a food allergy or not. This can be performed at home in less severe cases of non-IgE-mediated allergy, but should always be performed in hospital when dealing with IgE-mediated allergy, irrespective of the severity of the symptoms in the past.
Key message: Positive tests for food allergies don’t give a simple “yes or no” answer about a child’s allergies. The test results must be interpreted based on the symptoms of the child when eating those foods. Interpreting these allergy tests incorrectly is one reason that some children get diagnosed with multiple food allergies or are told that they are “allergic to everything.”
Many infants or children with CMA present with faltering growth, but not ALL4,5. Clinicians should therefore not dismiss the possibility of food allergies in a child just because they appear to be thriving and growing well.
Key message: Do not wait for signs of malnutrition or growth faltering in an infant or child before you consider a diagnosis of CMA.
Severity of reactions to foods in children suffering from IgE-mediated food allergies are mostly unpredictable. When reactions occur, they can be the same, less severe, or more severe than previous reactions6. Additionally, the child may not always experience the same symptoms of an allergic reaction (for example, an individual may have hives with one reaction, and vomiting with a subsequent reaction)7. The nature of a reaction depends on the child’s general health at the time, emotional state and the dose of the allergen that was ingested, as well as the food the child is allergic to. For milk and egg, symptoms seem to follow a more predictive pattern than for peanut allergy.
Key message: In children suffering from CMA who can tolerate smaller amounts of cows’ milk consumed in the diet, there may be a risk of more severe reactions and parents should be aware of this and know how to deal with any reactions.
It is true that peanuts can cause very serious reactions, but other foods have been known to cause severe reactions as well. In the UK, the main foods leading to death include milk, peanuts, nuts, fish, shellfish, snail, sesame, egg and tomato8.
Key message: All children with IgE-mediated food allergy could potentially develop more severe reactions, such as breathing difficulties or anaphylaxis. This risk increases in children with co-existing asthma9.
CMA usually develops in the first year of life and is one of the most common allergies seen in childhood, with a documented prevalence of between 2-7.5% in young children under five years10,11. Most children who have food allergies are allergic to fewer than 4 foods and these usually include egg, peanuts and soya, alongside cows’ milk12,13.
Key message: Although many parents’ concerns regarding suspected food allergies may be unfounded, they should never be ignored and a good diagnostic work-up to either diagnose or refute food allergies is always recommended. Only foods proven to have caused allergies should be avoided from a child’s diet. This may be more difficult during the weaning period where clinical tolerance to foods not previously eaten is uncertain.
The European Academy for Allergy and Clinical Immunology (EAACI) and World Health Organization (WHO)14 state that a cows’ milk allergy involves the immune system, while a lactose intolerance does not. The majority of symptoms caused by cows’ milk in infants are due to an allergic reaction to the proteins in the milk, referred to as IgE-mediated cows’ milk allergy (see table) or non-IgE-mediated allergy. Lactose intolerance means that the infant does not digest lactose (sugar in milk) sufficiently, which can result in symptoms of diarrhoea, bloating and perhaps colic/tummy ache10.
Key message: Symptoms such as diarrhoea, vomiting and reflux can be due to CMA and do not, in most cases, indicate intolerance to milk (lactose intolerance).
|IgE Mediated||Non-IgE Mediated|
|Skin||Urticaria (acute and chronic)
|Gastrointestinal System||Nausea and vomiting
Colicky abdominal pain
Angiodema of lips tongue and palete
Loose of frequent stools
Blood in stools
|Respiratory||Upper respiratory tract systems
Lower respiratory tract systems
|Lower respiratory tract systems|
Other system allgeric reactions
Research suggests that about 70% of food-allergic children show signs of eczema. Looking at this from another angle, about 30% of children with moderate to severe eczema show signs of food allergies, usually cows’ milk and egg allergies15.
Key message: do not dismiss the possibility of food allergy in children with moderate to severe eczema.
As children grow older, some may be able to tolerate foods that they previously were allergic to. This is more likely to happen in the case of allergies to milk and egg. Population-based studies indicate tolerance rates to cows’ milk in >80% of cases by 3 years of age13,16. However, a recent study in the US17 challenged these high rates of clinical tolerance, which may not be relevant for children seen in tertiary referral centres as only 5% of those referred were tolerant at age 4 and 21% at age 8. Remission rates to peanuts and tree nuts are, however, much lower.
Key message: Children with CMA should be reviewed regularly to establish the development of tolerance and prevent the unnecessary restriction of dairy foods from their diet.
Whilst some children may react to even trace amounts of milk in food, some may be able to tolerate small amounts in baked or cooked food18. Avoiding a food, whatever the extent of the avoidance required, can adversely affect the quality of life for families19. It may not be too difficult to avoid obvious sources of a food, but the real problem is when food contains the allergen (e.g. milk or egg) as part of their ingredients. Constantly reading food labels and asking about the ingredients of food in restaurants, enquiring about what they eat at school, or at the home of a friend or family member can be very difficult for some parents.
Key message: Always seek the advice of a dietitian when dealing with CMA. “One diet fits all” does not apply to children with food allergies and individual levels of tolerance should be taken into account. Dietitians can give practical advice on food avoidance, suitable substitutes and lifestyle advice.