iThei mdcdaelcinfd o c elllllrllll tcdhsfThtbse“One man’s meat is another man’s poison.”
—Lucretius (Roman philosopher and poet)15: Intolerances
A food intolerance is different from a food allergy. Although both types
of reactions are mediated by the immune system, completely different
mechanisms are involved.
IgE Food Reaction
Classified as a type I hypersensitivity, a food allergy is mediated by
immunoglobulin E (IgE) and manifests as hives and difficulty breath-
ing. It is considered an immediate type of reaction. IgE allergies are
also associated with allergies to medications like penicillin; bee stings;
nuts; and shellfish as well as those pesky seasonal allergies we have to
pollen and ragweed. The most accurate test for these types of allergies
is a skin test in which an allergist scratches the surface of the skin with
the allergen and observes for rashes to see if the person is reactive to
the substance. Blood tests are also available but are less sensitive. This
type of allergy is often called a “true allergy” by medical professionals.
This terminology is a misnomer, however, and suggests only IgE allergies
exist and that reactions mediated by different parts of the immune sys-
tem are nonexistent. Challenge any medical professional to review their
Immunology course notes, and they will find there are additional types of
hypersensitivities just as “true” and “real” as IgE anaphylactic reactions.
The two relevant hypersensitivities are mediated by immunoglobulins A
and G, IgA and IgG respectively.
For lack of better terminology, IgA and IgG hypersensitivities have been
labeled as “food intolerance” or “food sensitivity,” but they are much dif-
ferent in their mechanism and propensity to cause harm in the body.
IgA Food Reactions (Celiac-Like)
IgA food intolerance is the more severe reaction and works primarily in
the intestines. Occurring in genetically predisposed individuals, it is an
abnormal response of the intestines to certain foods. These intolerances
may manifest early in childhood or later in life.