Allergies

In a posting on some cartoons yesterday, I mentioned what I described as an “aversion” to cilantro that affects many people, an aversion that turns out to be genetically determined: people with Yuck Cilantro genetics (hat tip to Benita Bendon Campbell on the term) find the taste of cilantro disgusting and don’t appreciate the pleasures that others experience. For some people, the effect goes well beyond distaste or aversion; they suffer extreme symptoms that cause them to characterize their condition as an “allergy”, treating the symptomology as a definition of allergy.

But the medical literature insists on a technical definition of allergy that requires an immune response involving the antibody immunoglobulin E (IgE); without this antibody, we are looking at a food intolerance (or non-allergic food hypersensitivity), even if its manifestations are extreme: vomiting, even anaphylaxis. According to this literature, there is much less food allergy in the world than people think — because ordinary people use the term allergy loosely and incorrectly.

Now, from the point of view of ordinary people, it’s the symptomology that’s important, not the cause of the symptoms, and whatever the cause, the major part of treatment will involve avoiding the foods that trigger the symptoms. In the circumstances, it would be useful to have a technical term like true allergy or allergy proper (to distinguish those cases where antibody-suppressing drugs might be effective parts of treatment) versus a term allergy of wider application, or else a specially invented wider term, like allergoid condition.

(As it happens, I have just spent a miserable night suffering from an allergoid condition –persistent stomach pain, just to the verge of vomiting, belching, profuse sweating — that was probably triggered by refried beans and is almost surely not a true food allergy.)

The term allergy started life as a technical term in medicine; from NOAD2:

ORIGIN early 20th cent.: from German Allergie, from Greek allos ‘other,’ on the pattern of Energie ‘energy.’

The cites in OED3 (Sept. 2009) are medical for some time: first cite 1907 in JAMA, 1908 in Lancet, 1911 in Arch. Internal Med., etc.

NOAD2 recognizes only one literal sense, the medical one (plus an informal metaphorical one):

a damaging immune response by the body to a substance, especially pollen, fur, a particular food, or dust, to which it has become hypersensitive.

– informal   an antipathy: their allergy to free enterprise.

OED3, however, covers both the narrow and wider usages:

Med. Originally: altered immunological reactivity to a foreign antigen following previous exposure to it. In later use: spec. an abnormal form of such altered reactivity (hypersensitivity) which causes damage to tissue and results in disorders such as hay fever, asthma, and eczema. Also (more widely): intolerance of or adverse reaction to a specific substance, esp. a food.

Whatever the source of a food allergy (in the wider sense), the condition can manifest itself along a continuum of gravity. Reported severe reactions, from several sources follow. Ellen Evans writes, “[Cilantro] tastes like soap and it makes me violently ill. Like lying on the floor of the bathroom between vomits assuming I’m going to die ill. If I eat more than a tiny bit.” Something similar from Jack Hamilton on onions, Billy Green on shrimp.

Note: allergies to one food don’t necessarily carry over to similar foods; a reaction to cilantro doesn’t necessarily extend to coriander (but Benita Bendon Campbell reports that for her it does: coriander sets off “big blisters in the mouth and throat”); a reaction to onions doesn’t necessarily extend to other alliums; a reaction to shrimp doesn’t necessarily extend to other shellfish, though for a great many people it does. Reactions to tree nuts and peanuts (TN + PN) are notoriously complex; from Wikipedia, quoted in my “Tree nut” posting:

Tree nut allergy, a hypersensitivity to dietary substances from tree nuts causing an overreaction of the immune system, may lead to severe physical symptoms. Tree nuts include almonds, Brazil nuts, cashews, chestnuts, filberts/hazelnuts, macadamia nuts, pecans, pine nuts (pignolia nuts), pistachios, and walnuts.

People with tree nut allergy are seldom allergic to just one type of nut, and are therefore usually advised to avoid all tree nuts, even though an individual may not be allergic to all varieties of tree nuts. Someone allergic to walnuts or pecans may not have an allergy to cashews or pistachios, even though close biological relatives often share related allergenic proteins. The severity of the allergy varies from person to person, and exposure can increase sensitization. For those with a milder form of the allergy, a reaction which makes the throat feel like cotton may occur. The raw nut protein usually causes a more severe reaction than the oil, and extra roasting or processing can reduce the allergic reaction. Those diagnosed with anaphylaxis will have a more immediate mast cell reaction and be required to avoid all exposure to any allergen-containing products or byproducts, regardless of processing, as they are prone to even greater sensitivity. [See my “Does this contain any X?” posting on the difficulties of carrying out this program.] An allergy test or food challenge may be performed at an allergy clinic to determine the exact allergens. New immunotherapy treatments are being developed for tree nut allergy.

Tree nut allergy is distinct from peanut allergy, as peanuts are considered legumes, whereas a tree nut is a hard-shelled fruit of certain plants. [But sometimes TN and PN go together]

And very similar reactions can have different sources. From Wikipedia:

Not all reactions or intolerances are forms of allergy. [Example: cow’s milk allergy vs. cow’s milk — lactose — intolerance]

Back to the terminology used in talking about these reactions. Billy Green on FaceBook on his shrimp reaction, using symptomology as the defining factor:

“Distaste” doesn’t quite carry sufficient weight, either, though it’s technically accurate. It’s not what most people would call a food allergy (i.e., I don’t go into anaphylactic shock, and I am unlikely to actually drop dead as a result of eating the wrong thing), so I sometimes shy away from using that word. But, technically, stomach cramps and vomiting are considered symptoms of a “mild” food allergy. So Ellen would be justified in saying that she is, in fact, allergic to cilantro.

Now there are food reactions that might reasonably be characterized as distastes, dislikes, or aversions: garden-varietydislike of cilantro; mild aversions to fish and shellfish for some people (while recognizing that many have reactions in the allergy zone); a disike for alliums and brassicas (especially Brussels sprouts), presumably because of the sulfur in them. These are dislikes on the basis of taste, but there are also dislikes on the basis of texture — from friends of mine: against scallops, against ika, against celery and fennel, against okra (for a great many people).

Contact allergies. So much for ingestion allergies (though I’ve said very little here about respiratory allergies, involving, for instance, allergenic pollens). The field of contact allergies is immense and complex, but once again we find the medical literature solid on insisting that an immune response involving IgE is the determining factor for using the term allergy, though this way of talking is much narrower than the usage of most ordinary people.

There is a considerable literature, for instance, about hypersensitivity to iodine, especially in tincture of iodine, in the antiseptic Betadine (povidone iodine), in dyes as radiocontrast agents, and in medical adhesive bandages or tape — and the relationship of these sensitivities to shellfish sensitivities. The consensus seems to be that shellfish allergy is independent of iodine contact sensitivity (which is a matter of “irritant contact dermatitis” (ICD) rather than a true allergy); that adverse reactions to iodine are not mediated by IgE; and that in the case of contrast dyes the reactions involve substances other than iodine.

Despite all that, anaphylaxis (“non-allergic anaphylaxis”) has been reported, and ICD reactions can be severe enough to resemble burns.

Best advice for treatment is that if someone complains of a bad reaction, the apparent trigger should be avoided, period.

My wife was hypersensitive to adhesive tape — resembling burns, indeed! — though had no problem with shellfish, but our daughter has pretty much the whole package of adverse reactions: to shellfish, to adhesive tape, to Betadine, and to tincture of iodine.

My man Jacques and I both got contact rashes from various plants, a serious annoyance for two such garden-oriented men. But our sensitivities didn’t overlap. So I would deal with the Victorian box, and he would deal with the red-stick dogwood.

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