Saturday 24 February 2018

Allergic to cow's milk? Get the right diagnosis

Milk allergy is one of the most common allergies.
Milk allergy is one of the most common allergies.

Dr Nina Byrnes

My baby is six-months-old. I have been breastfeeding up to now but I would like to wean her to formula milk. However, I'm worried about allergies - we have a lot of them in my family. I am sensitive to dairy and so I have avoided it. How can I tell if my baby has an allergy to cow's milk?

Dr Nina Byrnes replies: It is estimated that about 5pc of children have an allergy to one or more foods. Milk allergy is one of the most common. It is thought to affect about 2.5pc of children under three years of age.

Nearly all infants who have cow's milk allergy develop it in the first year of life. Milk is a very healthy food and it helps build bone strength, so knowing for certain whether your child has a true allergy or not is very important.

It has been suggested that cow's milk allergy is over-diagnosed by parents and under-diagnosed by doctors, and this is probably true. The reason may lie in the fact that the symptoms of cow's milk allergy can vary greatly from person to person and from quite mild or subtle symptoms to those that are severe or life threatening.

Cow's milk allergy can occur in breast and bottle-fed infants but is more common in those who are formula fed. Weaning can be a time when this becomes most apparent.

Cow's milk allergy occurs when the human intestine is exposed to the proteins in milk. It becomes irritated allowing some allergic proteins to be absorbed into the body. The body then sees these as foreign bodies and activates the immune system trying to attack them, leading to symptoms consistent with an allergy.

The two main proteins in milk that cause allergy are casein and whey. It is possible to be allergic to one or both of these proteins in milk allergy. These proteins can also be present in certain processed foods such as tinned tuna, drink mixes, energy drinks and even some chewing gums. Those with milk allergy may also be sensitive to the proteins found in goat and sheep milk and even in some cases from soy milk.

Symptoms of cow's milk allergy vary greatly and may occur within a few minutes to hours or even days after ingesting the food. They include obvious allergic symptoms such as itching, a rash on the face or body, hives, tingling of the lips or mouth, a runny nose, watering eyes, wheezing or shortness of breath.

More subtle symptoms include irritability, abdominal pain and cramping, vomiting, loose stool which may contain blood or food refusal. Cow's milk allergy has also been implicated in recurrent sinus and respiratory complaints but the evidence for this in medical studies is lacking. In severe allergy there may be a risk of anaphylaxis.

If you suspect your child may have a cow's milk allergy discuss it with your doctor. Removing cow's milk from the diet and then reintroducing it and seeing if there is a change in symptoms can help if more subtle symptoms are present.

A blood test can be done to check for levels of IgE in the blood. This is a substance that increases in the presence of certain allergies. A specific test for antibodies to cow's milk is also possible. Skin prick tests to check for specific allergy are also sometimes recommended.

If your baby is diagnosed with cow's milk allergy and you are breastfeeding it is important you avoid too much dairy as the protein may cross in breast milk and flare allergies. If your baby is formula fed your doctor may advise using a hypoallergenic formula. There are two types.

It is also important to remain vigilant and to read food labels carefully looking for evidence of cow's milk, casein, or whey-based products. These may be present in non-dairy foods. If reactions have been severe it may be necessary to take antihistamines and to carry an Epipen (adrenaline).

Once a child is switched over to hypoallergenic formula there should be an improvement in symptoms and they should be gone within two weeks. It does take some infants time to adjust to the taste of the new formula and may be fussy during the initial changeover. Cow's milk allergy should not be confused with lactose intolerance. This is not an allergic reaction to milk. Those with lactose intolerance are missing the enzyme lactose which normally acts in the gut to break down lactose, the sugar found in milk. Lactose intolerance may cause symptoms such as abdominal pain, bloating, nausea, gas and diarrhoea but it is not an allergy and is not life threatening. Lactose intolerance can be diagnosed by sending a stool sample.

Although cow's milk allergy is relatively common the good news is that most children will outgrow this allergy before they are three. Eighty percent of those affected will outgrow it by the time they are 18.

I would not advise cutting out cow's milk from your daughter's diet just because you have sensitivity to dairy products. You must be certain of a true allergy before eliminating it from the diet. I would advise initially introducing small amounts of formula while you are still partially breastfeeding and see how she tolerates the change. If she becomes unsettled or unwell or develops any of the symptoms listed above then do visit your doctor and discuss whether she should be referred for testing. If she has a cow's milk allergy then linking in with a registered dietician will help ensure she has an adequate balanced diet.

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