Various extraintestinal symptoms have been ascribed to adverse food reactions.
In this chapter, only food hypersensitivity reactions are addressed (Table 1).
Contrary to most animal species, the human fetus acquires maternal immunoglobulin
G (IgG) via the placenta (1) and probably to some extent from swallowed amniotic
fluid via Fc-y receptors expressed by fetal enterocytes (2).
The intestine is routinely exposed to a limitless variety of macromolecules derived
from many sources, including resident bacteria, ingested food, invading viruses, etc.
It is my intent in this chapter to clarify the role of the nervous system in the
regulation and control of a variety of factors that are important in allergic manifestations
in the gastrointestinal tract.
A compilation of food allergens can be found in several reviews (e.g., see ref. 1).
Such a list, of course, is of interest from both a diagnostic and a dietary point of
There is a growing awareness among the public regarding what is termed "food
allergy" and a perception that a variety of distressing physical or psychological problems
and disabilities may be caused by food, methods of food production (agricultural
and industrial), and addition of substances used in promoting animal growth or to
preserve and stabilize processed raw supplies, beverages, drinks, and even domestic
The analysis of the intestinal mucosa usually requires intestinal biopsies of the
proximal small intestine.
Atopic diseases are important causes of morbidity throughout the world. The severity
of allergic diseases should not be underestimated and their prevalence is increasing.
The goal of this chapter is to review the methodology to be used in the evaluation
of complaints of adverse reactions to foods in order to confirm or refute the reported
Fussing and crying, especially in the evening, are normal developmental phenomena
in infants in the first 3 months of life (1). It is claimed that unexplained paroxysms
of irritability, fussing, or crying that persist for more than 3 hours per day, for more
than 3 days in one week (2), represent a separate clinical condition termed colic (3).
The diagnosis of food allergies and pseudoallergies remains one of the most challenging
and frustrating areas of allergy medicine.
Oral (food) tolerance" usually describes a clinical situation that is not necessarily
synonymous with the immunological definition of "tolerance," that is, as observed
during development, transplantation or neonatal tolerance. In the context of this
chapter, "oral tolerance" is defined as an antigen-specific immunological hyporesponsiveness
after prior enteral administration.
Oral immunologic tolerance or oral tolerance may be described as a state of systemic
unresponsiveness to parenteral immunization that is induced by prior antigen
Immunologic tolerance may be defined as a state of antigen-specific unresponsiveness
induced by preexposure to an antigen. If the antigen is an allergen, the
immune response is defined as allergy, an adverse reaction with an immunologic
basis mediated by IgE immunoglobulin (1).
Manipulation of the maternal diet during the pregnancy period or during both pregnancy
and lactation has been suggested as one way to protect the child from the
development of allergic disease.
The formidable increase in prevalence and morbidity of atopic disease, including
possibly food allergy, that is occurring throughout the world demands identification
of actions that promote allergy prevention.
There has been a recent revival of interest in the interrelated topics of atopic
disease and food allergy.
Atopic diseases play a major role in the morbidity of the developed industrial
countries. The most susceptible members of the population are children. About 20%
to 30% of the children below the age of 15 years are affected by one or more of the
typical atopic diseases such as allergic asthma, allergic rhinoconjunctivitis, atopic
dermatitis, and/or food allergy (1-6).
Immunoglobulin E (IgE)-dependent food allergy is involved in a number of diverse
clinical conditions (1,2). Diagnosis is carried out in two steps.
The first weeks of life seem to be a critical period for the development of allergic
manifestations to food antigens and particularly to cow's milk proteins. Indeed, it
has been shown that in infants with cow's milk allergy supplements of cow's milk
formula are given significantly more often in the first 4 weeks than in control infants
without cow's milk allergy (1).
Recent statistics show a dramatic increase in the number of patients with allergic
disease in the advanced nations of the world. Even Izuoshima Island in Japan, which
has no environmental pollution, has been shown to have increased childhood asthma,
allergic rhinitis, and atopic dermatitis rates (1).
One of the recent problems of industrialized societies is an increasing incidence
of allergy. It has been estimated that one out of four Japanese people has some
sort of allergic symptoms.
Food allergy is frequently associated with other atopic manifestations during infancy
and early childhood. Proteins of hen's egg and cow's milk represent the most
common clinically relevant allergens.
At least from my point of view, the striking feature of this meeting was that it
shows that the topic of food allergy has at last really become a part of medical science.
We are now well on the way to describing truly objective findings.