Wednesday, April 20, 2011
milk allergy is the most common food allergy in young children,
affecting about two percent of children under four years of age.
It is the third most common food, after peanut and tree nuts,
responsible for food-induced anaphylaxis in pediatric population. This
food allergy presents with a wide range of clinical syndromes due to
immunologic responses to cow's milk proteins that can be immunoglobulin
(Ig)E- and/or non-IgE-mediated. IgE-mediated food-triggered reactions
generally occur immediately, within minutes to two hours after
ingestion. These reactions can present with skin, upper and lower
respiratory tract, gastrointestinal tract, and/or cardiovascular signs
All milk proteins are potential allergens. Cow's
milk contains casein and whey proteins that account for approximately
80 and 20 percent of total protein, respectively. Cooking diminishes
the allergenicity of whey proteins, presumably by denaturation of
heat-sensitive proteins. This may explain why extensively heated milk
(eg, milk in baked goods) is better tolerated by many patients.
Similarly, yogurt cultures, which ferment and acidify milk, diminish
the amount of intact whey protein in milk and may result in tolerance
of yogurt-based dairy products by individuals with cow’s milk allergy
exclusively sensitized to whey proteins.
Sample conditions affected by milk allergy:
Atopic dermatitis (eczema) — Food allergy plays a pathogenic role in a subset of patients, primarily infants and children, with atopic dermatitis.
Allergic gastrointestinal disorders —
Milk is also among the major allergens identified in allergic
eosinophilic esophagitis. Patients with this disorder have symptoms
suggestive of gastroesophageal reflux, but are unresponsive to
conventional reflux therapies. Other presenting symptoms include
feeding disorders, vomiting, and abdominal pain. Patients with allergic
eosinophilic gastroenteritis may have symptoms of abdominal pain,
nausea, vomiting, diarrhea, or weight loss.
Gastroesophageal reflux — Symptoms in gastroesophageal reflux may be associated with cow's milk allergy.
Cow's milk allergy/intolerance has been suggested as a cause of
constipation in infants and children, especially in those with chronic
diagnosis of cow’s milk allergy is based upon the history and
laboratory testing. The gold-standard diagnostic procedure may include
elimination of the suspected food, challenge, and re-elimination. In
breastfed infants, this includes a maternal exclusion diet avoiding
cow's milk protein. In formula-fed infants, the use of either
extensively hydrolyzed or amino acid-based infant formulae is
recommended. If minimal to no improvement is noted on a milk avoidance
diet, the food in question is not responsible for symptoms, the diet
has not been restricted enough, or the patient may have multiple food
allergies and additional foods may be considered suspicious.
Measurement of cow's milk-specific IgE can aid in the diagnosis of
IgE-mediated cow’s milk allergy and may eliminate the need for oral