Firstly, it is important to make the distinction between a milk allergy and lactose intolerance. While a milk allergy is an abnormal immune response to milk protein, lactose intolerance is an inability to digest milk sugar. Although an intolerance is not life threatening and is less serious than an allergy, it can adversely affect day to day life (abdominal pain, diarrhea).
In those with milk allergies, the immune system mistakenly identifies certain milk proteins as harmful. When such individuals are exposed to these proteins for the first time, their immune system produces antibodies. When they come into contact with milk proteins again, they produce even more antibodies as well as other chemical substances including histamines. Histamines, which play a major role in allergies, cause reactions throughout the body (reactions in the digestive and respiratory systems and skin reactions).
Persons at risk
Milk allergies generally affect preschool children. It is estimated that between 2-3% of children, on a global scale, have milk allergies. It is the most common allergy in children under one year old. However, in the vast majority of cases, children outgrow cow milk allergies by the time they are two or three years of age.
Symptoms, which differ from person to person, are often based on the severity of the allergy. Common immediate-type reactions (occur within two hours of having ingested a product) include:
- Anaphylactic shock (swelling of the airways) - which is rare
- Hives (red, itchy skin)
- Projectile vomiting
Delayed-type reactions, which can occur several hours after having ingested a product, include:
- Digestive problems (gastro-esophageal reflux, bloody stools, colic)
- Hives (red, itchy skin)
Children with milk allergies are more likely to develop other health problems such as reflux and other types of allergies (ex: hay fever).
There are tools to detect whether cow's milk protein antibodies (synonymous with allergy) are present in the body. Those tools include skin and blood tests. Milk allergies are easier to detect through skin tests. A blot paper soaked with milk is placed on the baby's skin for 48 hours. Skin reaction is then assessed.
Once a milk allergy is confirmed, the best way to deal with it is to remove cow's milk from one's diet. This is known as an elimination diet.
For infants who are not being breastfed, soy-based or hydrolyzed protein formulas (broken down into tiny pieces to virtually eliminate reactions) are sound choices. However, in 40% of cases, infants who are allergic to cow's milk protein are also allergic to soy protein. As for hydrolyzed protein formulas (ex: Alimentum®, Nutramigen®), they are more expensive than regular baby formula and are not totally without risk. Regular milk can be reintroduced gradually. However, if signs of allergy develop, the child must revert back to a hydrolyzed formula. Changing baby formula must be done under medical supervision.
If a problem is detected in an infant who is being breastfed, the nursing mother may have to follow an elimination diet that involves cutting cow's milk protein from her diet. In fact, beef protein can be detected in breast milk. In this case, consultation with a dietician is recommended.
Despite everything you have just read, breastfeeding your infant, from the time they are born until the age of 6 months, remains the best way to protect them from developing allergies later on in life. After the age of 6 months, you can begin to diversify your child's diet by adding nutrient-rich foods. Protecting your child from second-hand smoke exposure also reduces their chances of developing other health problems.
It should also be mentioned that reading product labels and ingredient lists is a good habit to get into. Milk and milk derivatives are found in a significant amount of foods and can be present under different names. Here are a few examples of the names given to dairy products:
- Casein or caseinate
- Lactate or lactose
- Opta™, Simplesse® (fat replacers)
- Modified milk ingredients
For more information:
Allergy/Asthma Information Association
Educational community resources
Food Allergy Information and Support