Cow’s milk allergy is an allergic reaction to the protein in cow’s milk2. Cow’s milk allergy can affect both formula-fed and breast-fed babies, since an allergic baby can detect the cow’s milk protein in the mother’s diet through her breast milk3. Symptoms can take place right after feeding, or can be delayed for up to a couple of days3.
Cow’s milk allergy is the most common type of food allergy in infants, affecting between 2% and 5% of babies and young children1. It usually develops before one year of age, and most children will grow out of it by age 5, when they might reintroduce cow’s milk into their diet1. It is not clear why some children develop food allergies such as cow’s milk allergy, or why some grow out of their condition whilst some remain allergic; however, rates of food allergy are increasing globally, particularly in young children4.
The role of our immune system is to protect our bodies against infections by attacking the viruses and bad bacteria {‘pathogens’) that can make us ill5,6. In a food-related allergic reaction, the immune system overreacts to a protein that is usually harmless (e.g. a peanut allergy is a reaction to the protein in peanuts) 5,6.
In cow’s milk allergy, the body's immune system reacts to the protein in cow’s milk, mistaking it for a harmful pathogen. When an allergic infant consumes cow’s milk or something that contains cow’s milk protein, their immune system has an allergic reaction.
Common symptoms of cow’s milk allergy fall broadly into three categories7-10:
Colic (excessive crying) is also known to be a symptom of cow’s milk allergy.
Allergic symptoms can happen immediately after feeding (e.g. severe breathing problems or vomiting) or be delayed by hours or days.
The symptoms of cow’s milk allergy are wide-ranging and non-specific – meaning they are also found in many other conditions. A diagnosis of cow’s milk allergy should always be made by a qualified healthcare professional.
Cow’s milk allergy and lactose intolerance are not the same. Although both are reactions by the body triggered by cow’s milk, an allergy and an intolerance are actually very different11.
While digestive symptoms can be found in both cow’s milk allergy and lactose intolerance, lactose intolerance does not usually affect the skin or the respiratory system11.
A family history of allergy (including eczema, hay fever or asthma) increases the risk of a baby developing a food allergy2. However, even babies with no family history of allergy can develop cow’s milk allergy; a baby’s environment can affect the likelihood of developing an allergy13-15.
Bacteria and other microorganisms (collectively known as the ‘microbiota’) in the gut have a role in the healthy functioning of the body, including the immune system16. When the delicate balance of the gut microbiota is disrupted and the number of bad bacteria outweighs the good bacteria (‘gut microbiota dysbiosis’), the immune system can start to react incorrectly to harmless things, such as milk protein5,6.
Gut microbiota dysbiosis is linked to an increased risk of food allergies, including cow’s milk allergy. 14-16 Specifically, infants with food allergies appear to have fewer good bacteria in their gut compared with healthy, breastfed infants17-19.
Things that can upset the balance of the gut microbiota include:
Gut health can be improved by good nutrition and consumption of prebiotics and probiotics24.
It is important that cow’s milk allergy is correctly diagnosed by a healthcare professional so that appropriate management can be initiated.
Diagnosing cow’s milk allergy can take a lot of time and visits to the doctor25, as some symptoms are also fairly common to non-allergic babies, or those with an intolerance.
Delayed diagnosis can be distressing for babies and their parents and can potentially harm a baby’s growth and development25.
Diagnosis by a healthcare professional is made based on symptoms, medical history and if necessary, baby allergy testing. An elimination diet – where certain foods are removed from the mother’s diet when breastfeeding, or a baby’s diet under the doctor’s guidance – may also be used to aid diagnosis26.
If you think your child or baby is allergic to milk, talk to your healthcare professional.
Breastfeeding is the very best nutrition for all infants. However, very sensitive babies can have allergic reactions to even small traces of cow’s milk protein found in breast milk.
If a baby is suspected to have a cow’s milk allergy, a healthcare professional may advise breastfeeding mothers to eliminate all products containing cows’ milk from their diets27. Always talk to a dietician / healthcare professional before making dietary changes.
When breastfeeding plus an elimination diet are not possible, there are hypoallergenic formulas specially designed for babies with cow’s milk allergy. Some contain cow’s milk protein, but the proteins are broken down until they are too small to cause an allergic reaction. Others contain no cows’ milk protein at all (for infants with severe cow’s milk allergy28. Symptoms usually disappear once what is causing the allergy is identified and removed from the baby’s diet27,28
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