Milk casein allergy: symptoms, what to do?

Milk casein allergy is a food allergy that mostly affects infants and children under 3 years old. It is manifested by redness and itching of the skin, as well as digestive symptoms, which occur more or less quickly after ingestion of milk. This allergy disappears spontaneously in the majority of cases. 70 to 90% of children are cured by 3 years.

 Definition of casein

Among the thirty or so proteins in cow’s milk, the most allergenic are β-lactoglobulin and caseins. These are responsible for long-lasting allergies.

Derived from the Latin term caseus which means “cheese”, casein is a protein which constitutes the major part of the nitrogenous components of the milk of mammals. For example, there are 30 g / L in cows and 9 g / L in women.

In the event of an allergy, the immune system reacts incorrectly against the casein, and produces antibodies to protect itself.

Casein is also used by some athletes as food supplements to build muscle mass and facilitate its regeneration. It is particularly widely used by body-builders.

 Where is milk casein found?

Casein is present in all foods containing milk, whether cow’s milk, goat’s milk, sheep’s milk, buffalo’s milk, mare’s milk:

  • butter
  • cream
  • cheese
  • milk
  • whey
  • ice

It is also found in beef, veal, baby food, powdered food supplements.

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It is also used in the composition of many other industrial products such as milk or white chocolate, sandwich bread, cookies, pastries, yogurts, ready-made sauces or even in industrial cold cuts.

 Symptoms of casein allergy

“Casein allergy is part of the allergy to all cow’s milk proteins, even if casein is the main allergen,” says Professor Christophe Dupont, allergist. “The symptoms are very diverse and can occur more or less quickly after ingestion of milk.”

We distinguish :

Immediate reactions

They occur less than 2 hours after ingestion of cow’s milk: hives, vomiting, abdominal pain, diarrhea with sometimes blood in the stool. And exceptionally, an anaphylactic shock with malaise.

Less acute and later symptoms 

As :

  • gastroesophageal reflux,
  • abdominal pain
  • colic,
  • bloating
  • weight loss.

“Allergy to cow’s milk proteins can also cause a skin reaction, with the appearance of eczema, red patches, itching, pimples.”

Respiratory symptoms

Like asthma, a cough or even a runny nose, can also appear.

Cow’s milk protein allergy should be distinguished from lactose intolerance which is not an allergic disease.

 Case in the baby

Allergy to milk proteins can appear as early as three weeks after birth and up to eight to ten months of age. 70 to 90% of children are cured by 3 years.

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It results in redness and itching of the skin, as well as digestive symptoms (regurgitation, vomiting, constipation, diarrhea or stomach aches).

In France, this type of allergy affects about one in forty babies. Although both parents have allergies, this disease affects about one in five babies.

Infants who suffer from an allergy to cow’s milk protein have a higher risk of developing another form of allergy as they grow older: food allergy, hay fever, asthma, for example.

 Adult case

“Most of the time, cow’s milk protein allergy heals before the age of three, which is why it is rare in adults.”

 Diagnosis of milk casein allergy

The diagnosis is mainly based on clinical symptoms, but also on skin tests (prick-test) which can be carried out in the office of the pediatrician or the allergist. The doctor will then prick the skin superficially through a drop of milk and observe the skin reactions.

A blood test may be prescribed to look for the presence of antibodies directed against cow’s milk proteins, immunoglobulins E (IgE). “Very often, the immunological mechanism does not involve IgE, so you have to know how to recognize allergy to cow’s milk proteins on clinical symptoms, even if the blood test is negative”.

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What to do in case of allergy

In adults, the treatment of allergy to cow’s milk proteins is based on an elimination diet excluding all milk foods from the diet. “Individual susceptibility can play a role. An adult allergic to cow’s milk protein can sometimes tolerate a small amount, especially if it is in very cooked form such as in cookies ”.

Regarding children allergic to cow’s milk proteins, the diet will differ according to their age.

Before 4 months, if the child is exclusively breastfed by its mother (without any cow’s milk supply), the mother can be suggested to follow a diet without cow’s milk protein for a few weeks.

If the child is not breastfed or if the mother is unable or unwilling to follow a diet that excludes milk protein, several solutions are available such as extended cow’s milk protein hydrolysates.

“We use more and more infant formulas made with rice protein hydrolysates, whose nutritional composition is perfectly adapted. Soy-based infant formulas (the use of which is only authorized from 6 months, due to their phyto-estrogen content) are now abandoned ”.