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6. Cows' milk allergy

6. Cows' milk allergy

Cows’ milk allergy (CMA), also known as cows’ milk protein allergy (CMPA), is the most common food allergy in infants and is more frequently seen in formula-fed than breastfed babies

CMA thought to affect two to 7.5 per cent of babies under one year of age, although the majority will grow out of it by the age of five years.

Symptoms

There are a number of different symptoms, which generally involve the skin and one or more other body system, including the gastrointestinal and respiratory systems. Symptoms may include:

  • Swelling of the face, hives, wheezing
  • Diarrhoea and vomiting
  • Constipation, bloating and abdominal pain
  • Colic.

Other symptoms can include eczema, rashes and breathing difficulties in severe cases (refer these cases to the pharmacist). Between 50 and 60 per cent of babies with atopic eczema will also have an allergy to cows’ milk, causing their skin symptoms to worsen.

Causes

The first time a baby has cows’ milk, whether in an infant formula milk or if it passes through breast milk, their immune system reacts to the protein it contains as if it were a foreign substance. The next time the baby has cows’ milk, the antibodies produced will trigger the various allergy symptoms.

Treatment

If you think a baby may be allergic to cows’ milk, refer them to the pharmacist as they may need to see a GP for a diagnosis. Total avoidance of cows’ milk protein is usually required, which may involve mothers of breastfed infants avoiding cows’ milk and dairy products, alongside taking appropriate supplements (e.g. calcium and vitamin D). The situation should be monitored using a food and symptom diary, with cows’ milk being periodically reintroduced at intervals under medical supervision. For formula-fed infants, a suitable formula will need to be found that is tolerated as a drink, and for use in cereals and cooking.  

The Department of Health and Social Care recommends that soya-based formula milks are not used before six months of age

Formula milks

There are several types of special infant formula milk available for cows' milk allergy. The latest guidance advises using an extensively hydrolysed formula (EHF), such as Aptamil Pepti 1 or 2 and SMA Althéra, which is still based on cows’ milk, although the proteins have been broken down to make them less allergenic. There are also amino acid-based formulas (AAFs), such as Neocate and SMA Alfamino, where the protein is made up of individual amino acids so that it does not trigger allergic reactions. AAFs are considerably more expensive, so are usually reserved for those with severe cows’ milk or multiple food allergies who cannot tolerate EHFs.

The Department of Health and Social Care recommends that soya-based formula milks (e.g. SMA Wysoy Soya Infant Formula) are not used before six months of age. This is because infants may also be allergic to soya protein and these formulas increase exposure to plant phytoestrogens while babies’ organ systems are immature and vulnerable. However, some milks are marketed from birth, as for some babies this may be all that they can tolerate. They can be used for babies who cannot tolerate the EHFs as they are more palatable, or for those who choose soya-based formula for lifestyle reasons, such as vegetarians and vegans. N.B. Vegan diets are not recommended for babies.

Help for parents 

Parents may require additional support and information, ideally from a dietitian, especially as their baby gets older and starts weaning onto solid foods. Knowing plenty of milk-free recipes will be helpful, as will buying dairy-free products. The labels of all foods should be checked as milk can be present where it is not expected.

  Clinical summary

Food allergy is an adverse immune response and may be immunoglobulin-E (IgE; an antibody)-mediated or non-IgE-mediated (in which case T-cells are thought to be responsible), or both. IgE-mediated reactions are acute and often have a rapid onset, for example skin reactions, angioedema (swelling) of the lips, tongue and palate, nausea and vomiting, respiratory symptoms (sneezing, rhinorrhoea, cough, wheezing or shortness of breath). Non-IgE-mediated reactions tend to be delayed, for example itching, atopic eczema, gastro-oesophageal reflux disease (GORD), changes in stools, tiredness and faltering growth.

According to NICE, diagnosis should be considered in a child whose symptoms do not adequately respond to treatment for atopic eczema, GORD or chronic GI problems including constipation, aided by taking an allergy-focused clinical history (e.g. personal and family history of atopy, symptom type, severity, duration and reproducibility, and dietary details). The child should also be assessed for physical signs of malnutrition or faltering growth, and signs of any allergy-related comorbidities.

Management of the suspected food allergy depends on whether or not IgE is thought to be responsible. If an IgE-mediated reaction is believed to be causing the infant’s symptoms, a skin prick test or blood test for specific IgE antibodies to the suspected food and co-allergens should be conducted. For non-IgE-mediated allergies, the suspected allergen should be eliminated from the diet for between two and six weeks and then reintroduced under medical supervision.

If cows’ milk protein allergy is suspected, the mother should be provided with advice on food avoidance if she is breastfeeding, or information on the most appropriate formula or milk-substitute if formula feeding. A referral to a dietitian may be required, as may signposting to support groups. Specialist care is recommended for individuals who experience faltering growth accompanied by GI symptoms that are thought to indicate a food allergy, have had one or more acute systemic or severe delayed reactions or have not responded to a single-allergen elimination diet, or if there is suspicion of multiple food allergies, even if test results are negative.

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