Allergy is a hypersensitivity reaction of the immune system to certain substances foreign to the organism. It is defined as a hypersensitivity reaction because, typically, these foreign substances do not cause such reaction in a healthy organism. Food allergies are quite common and they are usually to foods such as: peanuts, tree nuts, eggs, fish, seafood, soya, wheat and milk. These form the so-called “big 8”. In babies and children up to 3 years old, leading is the cow’s milk protein allergy (CMA). About 3% of children suffer from this allergy and it is believed that they will “outgrow it”, typically by the age of 3 – 5 years. Cow milk contains two types of protein: whey and casein. The allergy can be to one of them or both together. It must be pointed out, that in cases of CMA there is often a cross-reaction with goat, sheep and buffalo milk, because their proteins are very similar. This means that affected children’s diet should exclude not only cow but also the aforementioned types of milk as well. The reason behind CMA is still not clear, but it is believed that genetic predisposition plays a key role, and also that it is more common in children suffering from atopic dermatitis. CMA is less common in breastfed babies. CMA may affect different systems and cause different symptoms:

• Gastrointestinal tract: vomiting, nausea, diarrhoea (with and without traces of blood), stomach pain
• Respiratory system: a runny nose, frequent coughing, wheezing
• Skin: eczema, itching

Symptoms may last a few hours (quick reaction) or a few days (slow reaction). Although rarely, an allergic reaction may lead to an anaphylactic shock – the lips become blue, the skin gets pale, there is shortness of breath, the pulse slows down. Such condition require immediate medical attention. In breastfed babies, symptoms appear after the mother consumes dairy products. If you suspect your baby may suffer from CMA, it is best to carry out an elimination/provocation test: remove milk, dairy products, coffee, chocolate (cacao), citrus fruits, beans, bananas, berries, butter, nuts, eggs, beef and veal from your diet for at least 14 days. The diet is expanded to cover the cross-reactions between the indicated foods which may cause allergic reactions. Also, veal contains a type of protein that is present in cow milk too. After the 14-day period the mother should try and consume a small amount of milk and dairy products. If any of the aforementioned symptoms appears, the diagnosis is confirmed and the mum should go on a strict diet for at least 6 months. In formula-fed children, standard formula should be substituted with hydrolysed formula milk (with the protein broken down which makes it easer to assimilate by the baby). Again for a 6-month period and after it introduction of standard formula happens gradually – start with 1 ml, then 5 ml, 10 ml up to 100 ml – within a few hours. Your paediatrician should strictly monitor the introduction of dairy products and foods which may cause allergic reactions in your baby’s menu. Typically, first to get on the baby’s table are the cheese, curd and yoghurt, and once the little one reaches 1 year and a half (and sometimes even after the 2 – 3 year) fresh milk is introduced.

As for the establishing of a diagnosis, there are also other markers that can be used:

• complete blood count which shows increase in the eosinophils count;
• total/specific IgE test (measuring the immunoglobulin E) in the blood which also shows an increase;
• in older children skin tests may be used;