Tuesday, 23 June 2015

What is Cows' Milk Allergy?

Cows milk allergy (CMA) (sometimes termed Cows milk protein intolerance) along with other food allergies, appears to be on the increase. It's not entirely clear why, but it means that up to 7.5% of children can have an adverse reactions with cow's milk. It is also more common in families where one or more individuals are "atopic" - that is, have problems such as asthma, eczema, or hay fever. 

An allergy develops when the body's immune system reacts to one or more of the proteins present in milk - usually casein or whey in the case of cow's milk. 

CMA differs from lactose intolerance in that CMA is caused by an immunological reaction. Lactose intolerance refers to an inability (usually in adults) to digest the sugar found in milk. 
CMA is usually present in infants, and symptoms are often apparent by the time the baby is 6 months old. 

What sort of symptoms should I look out for?

There are two types of CMA. These are referred to as IgE or non-IgE mediated. 

IgE is an antibody that primes the body for an allergic response. (see Wikipedia if you want to know more). 

IgE mediated 

IgE mediated response is termed the acute or immediate response. With this type of allergy, you see symptoms such as:

  • Hives - "Urticaria"
  • Eczema, 
  • Lip and facial swelling
  • Abdominal pain, vomiting, diarrhoea, 
  • Difficulty breathing or wheeze. 
  • Nasal congestion, sneezing. 
  • Anaphylaxis - see below. 

Symptoms of Anaphylaxis need immediate medical attention:

Severe wheezing and chest tightness
Swelling of the face, tongue, lips and upper airway
Difficult or noisy breathing. 
Shock (as a result of lowered blood pressure)
Dizziness and unconsciousness 

Diagnosis in these circumstances can often be obvious due to the immediacy of the reaction, but your doctor can advise if blood tests or skin prick tests are needed. 

Non-IgE mediated 
Non-IgE is the type that T has. It is a much more "slow burning" type of allergy, and may take hours or days (or even weeks!) to become apparent. This is because a lot of the symptoms are less well defined. Often, parents may seek help for other problems, such as reflux, or may simply decide that they have a "difficult" baby before the penny drops.

The symptoms of non IgE mediated CMA include:

  • Vomiting or frequent regurgitation,
  • Irritability and colic, 
  • Diarrhoea or constipation,
  • Blood or mucus in stools,
  • Nappy rash,
  • Eczema, 
  • Chestiness, 
  • Chronic cough, 
  • Poor growth. 

Diagnosis can take longer in these circumstances, as there are often no suitable tests to perform. In these circumstances, it can be useful to have a food diary to document all of baby's food intake and record any adverse reactions. 

Keep a Food diary when weaning 

If the symptoms resolve with the exclusion of cows milk from the diet, (an "elimination diet") the diagnosis is much more likely. 

Please don't exclude food groups from you or your child's diet without seeking advice

Breastfeeding and CMA

Exclusive breastfeeding remains the gold standard of feeding babies until the age of 6 months.

Babies who have yet to be weaned and are breastfed may exhibit CMA symptoms as small amounts of cow's milk protein is present in breastmilk. These amounts are tiny (100,000 times smaller than cow's milk), so severe symptoms of CMA are very rare in exclusively breastfed infants. This may also be in part to the protective effect of breastfeeding on the baby. 

Managing a breastfed baby who has proven CMA, involves the mum excluding dairy from her own diet. However, such an intervention should not be taken lightly, as the mum needs to ensure she is still getting an adequate intake of calcium and vitamin D. 

Formula feeding and CMA

If you have decided not to breastfeed, were unable to, or need to bridge with top ups to get back to exclusive breastfeeding, then you should be offered a special type of formula on prescription from your GP:

  • Extensively hydrolysed formula (EHF) - the proteins that cause the allergy are broken down or "hydrolysed" until the body's immune system no longer recognises them an allergenic. 
  • Amino acid formula (AAF) - the proteins are in their base form, called amino acids, and do not trigger an allergic reaction. 

It is important that your baby does not have milk that is from other sources such as buffalo, goat, sheep, horse, or goat. The protein that causes the allergy is also present in these milks and so should not be given. 

Soy and rice milk are not recommended. They do not have the nutritional content to provide for your baby. Soy milk causes problems as it can lead to adverse reactions in some babies with CMA, and has photo-oestrogens which are unsuitable, especially for boys. (I will cover soy in another post at some point). 

For further information regarding the diagnosis of CMA, please have a look at the Resource page, I will be adding to it all the time. 

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