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Because food allergy treatment is basically avoidance of the offending food(s), identification of the latter becomes the cornerstone for management. At present, the elimination-challenge test is the most definitive procedure for verification of a cause-and-effect relationship between a particular food and a certain reaction, allergic or not. The oral challenge test is most reliable when conducted in a double-blind, placebo-controlled manner. In routine clinical practice, however, single-blind testing is satisfactory in most cases. Open challenge testing might be acceptable in young children or for screening the least suspected foods. It would be prudent to avoid the test, in any of its forms, in instances where a specific food caused a life-threatening reaction. Caution needs to be practiced in planning, conducting, and interpreting the results of challenge tests. Difficulties may be encountered in disguising the test food, choosing a placebo, reproducing the natural exposure, incorporation of possible associated factors, and avoiding any bias on the patient's or observer's part.

Milk hypersensitivity is a problem that can have substantial health, financial and social implications. The condition is underdiagnosed by some physicians and overdiagnosed by others probably because its symptoms are varied and shared with many other diseases. The gap in our knowledge on the pathogenesis of various manifestations of CMA has been only partly bridged by the information accumulated in recent years. It has become clear that milk-sensitive patients are heterogeneous, both regarding symptomatology and underlying pathogenic mechanisms.

Changes in serum IgG4 levels during heterophil-positive infectious mononucleosis were recorded. Pre-illness serial acute and convalescent specimens were evaluated. Mean IgG4 levels increased by 75% during acute infectious mononucleosis, reached a peak 21/2 to 3 weeks post-onset, and declined to baseline by 60 days. IgG4 peaked independently of other immunoglobulin classes.

Sera of 17 patients with gluten-induced celiac disease were studied. Total serum IgE and IgD, as well as specific IgE and IgD antibodies to selected food antigens, were determined. Total IgE levels were within the normal range. Specific IgE antibodies to wheat, alpha-gliadin, cows's milk, rice and buckwheat were comparable to those of normal controls. In the celiac subjects total IgD levels were also within the normal range but IgD antibodies to wheat were high whereas IgD antibodies to milk were lower than in pooled normal sera. The levels of IgE or IgD antibodies to either wheat or milk showed no relationship to the presence of precipitins to the antigens of these two foods. The study did not demonstrate a role for IgE in celiac disease. That IgD antibodies may play a role is suggested by the elevated serum IgD antibodies to wheat antigens.

To date the most reliable procedure for the diagnosis of milk hypersensitivity is a properly conducted elimination-challenge test. Several in vitro tests have been developed but because of the diverse underlying mechanisms of hypersensitivity reactions to milk developing a single laboratory test that can be universally positive in every patient would be rather difficult. However, with a better categorization of milk-sensitive patients, together with the development of relevant, standardized and practical tests, the laboratory diagnosis of milk allergy should become more reliable. Milk hypersensitivity can be effectively treated and is largely preventable. Avoidance is the most effective mode of treatment and results in a good prognosis. In instances where the desired degree of avoidance cannot be attained pharmacologic agents may be of help. The need still exists for developing an effective procedure of hyposensitization. For prevention, prolonged breast feeding should be recommended, especially in infants of atopic families.

The increasing awareness by the medical profession, as well as the public, of food allergy imposes the parallel task of accurate diagnosis and proper treatment. A carefully obtained medical history and a properly conducted elimination-challenge test are the most valuable as well as the least expensive procedures for diagnosis. Other selected in vivo and in vitro tests may enhance the diagnostic ability and may verify the immunologic basis of the food-induced reaction. Treatment is basically dietary avoidance, and its success depends on several factors. Pharmacologic agents may be needed for symptomatic treatment, and in certain instances for prophylaxis. The need still exists for developing an effective procedure of hyposensitization.

The mainstay of successful management of food allergy is the identification of the offending food(s), as verified by the elimination-challenge test. Dietary elimination is the most effective and inexpensive method, but its success depends on several factors. Initially, dietary elimination may need to be strict, but later certain patients may discover that they can tolerate limited quantities or certain preparations of the offending food without significant symptoms. In certain cases, provision of a substitute or a nutritional supplement may be needed. Food allergy in infants who are exclusively breast-fed requires elimination of the offending food from the mother's diet. Because of cross-antigenicity, certain patients may also need to avoid other members of the food family. This phenomenon is especially noticeable among seafoods. In certain patients who have mild to moderate sensitivity to multiple foods that cannot be completely avoided, rotation diets may be both effective and more convenient. In a few patients, conventional elimination diets may be followed for limited time periods until all offending foods are identified. In addition to symptomatic treatment, pharmacologic agents may be taken for prophylaxis. Antihistamines, oral cromolyn and possibly other medications, when taken before an anticipated exposure or on a regular basis, may prevent or minimize the symptoms in certain patients. At present, no adequate evidence supports the use of hyposensitization therapy with food extracts. The prognosis of food allergy is more favorable in children than in adults. Most food-sensitive infants and young children will tolerate the offending food after 1-2 years of avoidance.