Alternative Medicine Review 1998 (Apr); 3 (2): 90-100 ~ FULL TEXT
Alan R. Gaby, M.D.
Food allergy is well recognized in clinical medicine as
a cause of acute attacks of asthma, angioedema and urticaria, and as a
contributing factor in some cases of eczema and rhinitis. These types of
allergic reactions are considered to be mediated by IgE antibodies, and
usually can be diagnosed by medical history and skin-prick or IgE-radioallergosorbent
Another type of food reaction, often referred to as "hidden"
or "masked" food allergy, has been the subject of controversy
for many years. Some practitioners have observed that hidden food allergies
are a common cause of (or triggering factor for) a wide range of physical
and emotional disorders. According to one estimate, as many as 60 percent
of the population suffers from undetected food allergies. 
A wide range of symptoms and disorders are reported to have a significant
allergy component. See Table 1. On the
other hand, many conventional physicians doubt hidden food allergy is a
common problem, and some even deny altogether its existence as a clinical
Skeptics emphasize the fact that many of the conditions
said to be related to allergy fluctuate in severity and have a significant
psychological component. Consequently, it may be difficult to distinguish
between a true food reaction and a conditioned (psychogenic) response or
a spontaneous exacerbation of symptoms. It also has been pointed out that
food-induced symptoms should not be called allergies unless an immune-mediated
mechanism can be demonstrated. While it is true many food reactions would
be more appropriately labeled food intolerance, the term "allergy"
will be used in this article in reference to adverse reactions to foods.
Proponents of the food allergy-disease connection argue
that hidden food allergies are often overlooked because they are difficult
to identify. Unlike the more obvious immediate-hypersensitivity reaction
that can trigger acute asthma or anaphylaxis, a hidden food reaction frequently
can be delayed by many hours or even several days.
Identifying a cause-effect relationship between ingestion
of specific foods and development of symptoms is said to be further complicated
by the tendency of people to become addicted to the foods to which they
are allergic. This so-called "allergy-addiction syndrome" has
been observed by numerous clinicians  and
appears to be consistent with Selye's description of the "general
adaptation" response to stress. [3,4]
Thus, patients often experience short-term relief after ingesting foods
which are later demonstrated to be the cause of their chronic symptoms.
This paradoxical response can render medical histories and diet diaries
virtually useless for detecting hidden allergies.
Hidden food allergies can usually be "unmasked"
by means of an elimination diet.  After
a patient has been on a hypoallergenic diet for a period of time (typically
one to three weeks), chronic symptoms disappear or improve and the body
reverts from a state of allergy-addiction (corresponding to Selye's adaptation
stage) to one of increased alertness and sensitivity (corresponding to
Selye's alarm stage). In this hypersensitive state, ingestion of an offending
food results in a rapid and exaggerated reaction, allowing the patient
to identify previously unsuspected allergens. See Table
2 for a list of foods most commonly associated with food allergies
Ideally, studies of hidden food allergy should be conducted
using double-blind, placebo-controlled food challenges, in order to rule
out placebo responses and spontaneous fluctuations in symptom severity.
Some of the research reviewed in this article has used a double-blind design;
and most of these studies have confirmed the importance of food allergy
in the etiology of certain chronic conditions. Most of the other studies
on food allergy have lacked placebo controls. Nevertheless, the results
of these studies have frequently been impressive, especially when compared
with results of conventional therapy. Following is a review of selected
studies on the relationship between food allergy and certain common medical