The newborn is generally healthy and seldom exhibits any allergic symptoms. The first problems often arise with the introduction of cow's milk into the diet. The baby develops symptoms such as vomiting, diarrhea and colic. The parents often notice the connection between feeding and symptoms but the doctor cannot, at this stage, give any clear answers. These gastrointestinal symptoms, although more common among bottle-fed babies on cow's milk formula, can even appear in breast-fed children and the mother may have to avoid cow's milk, dairy products and eggs in her own diet since these proteins may be secreted in the breast milk.
Cow's milk hypersensitivity includes different conditions: lactose intolerance due to lactase deficiency, cow's milk allergy with elevated IgE antibodies and other non-IgE-mediated hyper-sensitivity reactions.
The diagnosis is approached through a detailed case history, the elimination of cow's milk from the child's diet with rechallenge when symptoms improve and demonstration of IgE antibodies to cow's milk (ImmunoCAP® ). Sometimes an investigation for coeliac disease is indicated, including tests for IgA/IgG antibodies to gliadin, IgA antibodies to tissue transglutaminase and intestinal biopsy.
The milk substitute must be of an appropriate constitution and osmolarity for the child's age, palatable and neither strongly sensitizing on it's own, nor antigenically cross-reactive with cow's milk. The most commonly used replacement for cow's milk is casein hydrolysate or soy-based milk substitute, the recommendations may however vary between countries. Some will become allergic to soy as well and then a formula made from hydro-lyzed casein is recommended.
Goat's milk has been demonstrated to have considerable antigenic cross-reactivity with cow's milk and frequently contains potentially pathogenic bacteria. All children fed with any cow's milk substitute must receive a calcium supplement. Breastfeeding should be recommended for the first 4-6 months, if possible without introducing any additional food.
New foods should be added one at a time and only one new food per week. With this procedure any hypersensitivity towards foods is more easily recognized.