A food allergy to cow’s milk is the most common food allergy in children. Fortunately, it is also a food allergy that is often outgrown by adolescence. While not usually as deadly as peanut allergies, dairy allergy reactions can range from mild, such as hives, to severe, including anaphylaxis.
The majority of dairy allergies are caused by alpha S1-casein, a protein found in cow’s milk. When alpha S1-casein is present, the body’s immune system reacts by releasing IgE antibodies. Milk proteins differ by species, so a child with a cow’s milk allergy may (but not necessarily will) handle goat’s milk and human breast milk without any problem.
About 2.5 percent of children under the age of three are allergic to dairy, most of whom developed their allergy before the age of one. By the time they turn four, nearly 90 percent of children allergic to dairy will have outgrown their allergy. The age that children are likely to outgrow their milk allergy is dependent on the amount of antibodies present in their blood, and all it takes is a simple blood test to develop an estimate of how long the dairy allergy will last. By adulthood, less than 0.5 percent of people are allergic to milk. Interestingly, about 20 percent of children with a cow’s milk allergy are also allergic to beef.
Other Problems with Dairy
Dairy allergies are commonly confused with lactose intolerance, a food sensitivity that does not involve the immune system. For children and adults with lactose intolerance, their bodies don’t produce the lactase enzyme, which is required to properly break down the lactose sugar found in milk. Extremely common, lactose intolerance is considered the norm for adults and is not considered a disease.
A less common condition is milk protein intolerance. This milk sensitivity is caused by a delayed reaction to milk protein. While its symptoms are similar to a milk allergy, milk protein intolerance doesn’t involve an immune system response and cannot be identified by an allergy test.
Foods to Avoid
Like other food allergies, an allergy to dairy cannot be cured, and the only effective treatment is strict avoidance of all foods containing milk or milk products. Cow’s milk yogurt, cheese, whey and butter all must be avoided, as should many soups, desserts and baked goods. In addition, products labeled “lactose-free” milk and “non-dairy” are unsafe and should never be consumed by someone with a dairy allergy. Milk proteins may also occur in small amounts in just about any food, from deli meats to condiments, so it’s important to carefully read all labels.
Note that any dairy allergy, even in cases with mild symptoms, has the potential to suddenly progress to a life-threatening anaphylaxis reaction; therefore, it is important that every child allergic to milk has an EpiPen or other epinephrine injector readily available.
Because it develops so early in a child’s life, a milk allergy can cause problems for babies being fed formula. Traditionally, formula is made using cow’s milk, so infants allergic to milk often require a special hypoallergenic formula. Usually, the alternative is a hydrolyzed formula based on casein that is extensively broken down so as not to cause a reaction, but in some cases, a soy-based formula might be necessary.
Having a young child with a dairy allergy can be frightening for parents, but they are far from alone. Fortunately, the most common food allergy is also the most likely to be outgrown by the end of a child’s toddler years. For the children whose dairy allergy lasts, however, careful management of their condition, including carrying an EpiPen and strictly avoiding milk products, will help ensure a healthy and safe childhood.